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Signalling Relays
Presented by P.Shakila Ios5
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RELAYS & CABLES
The orthodox mechanical signalling system was replaced with Electrical signalling.
Two essential components are widely used in all the Electrical signalling systems. They are "Relays" & Cables ".
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INTRODUCTION :
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RELAY CABLE
What is a Relay ?
A relay is an electromagnetic device used to convey information from one circuit to another circuit through a set of contacts i.e. front or back contacts.
Switching device used for remote control and succession control of various electrical equipment.
Capable of protecting the controlled equipment from cross feeding and overloading
Cater for speedy operations.
Most of the relays in present day signaling are electromagnetic devices,
But even the electronic components like diode/transistors/ Integrated Chips etc are also used as relays
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Principle-Electromagnetic relays
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Advantages of Relays
Relays can switch AC and DC, transistors can only switch DC.
Relays can switch high voltages, transistors cannot.
Relays are a better choice for switching large currents (> 5A).
Relays can switch many contacts at once.
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Disadvantages of Relays
Relays are bulkier than transistors for switching small currents.
Relays cannot switch rapidly whereas transistors can switch many times per second.
Relays use more power due to the current flowing through their coil.
Relays require more current than many chips can provide, so a low power transistor may be needed to switch the current for the relay's coil.
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Classification of Relays:
1 Based on their application,
Line relays
Track Relays
Lamp Proving Relays
Timer Relays
Flasher Relays
Contactor Relays
Biased Relays
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LINE RELAY TRACK RELAY
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LAMP CHECKING RELAY
TIMER RELAY
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CONTACTOR RELAY BIASED RELAY
Classification of Relays:
2 Based on type of contact material used
Metal to Metal contact Relays
Metal to Carbon contact Relays
3 Based on polarity requirement
Polar Relay
Neutral Relay
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Classification of Signaling Relays
4. According to their importance in ensuring train safety
a) Vital relays : relays directly used for
traffic control like signal, point, track
detection etc.
b) Non-vital relays : relays used for controlling aids like warning buzzers, indications etc.
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Classification of Signaling Relays
5. According to special provisions to ensure reliability of their contacts
a) Proved type : Relays for which proving of normalization is necessary after every
operation (metal-to-metal contact relay).
b) Non-proved type : Relays for which above requirement is not necessary as their contacts have at least one non-fusible contact (Metal to carbon contact relays).
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Classification of Signaling Relays
6. Based on the source of feed
a) DC relays
i) DC neutral relays : are not affected by the polarity of DC supply and close same set of contacts on energization.
ii) Polar relays : are sensitive to polarity of DC supply and
close different sets of contacts depending upon the polarity of the DC supply.
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Classification of Signaling Relays
b) AC relays : AC induction motor track relays are used at some places in DC electrified area.
c) Electronic relays- DC relays with electronic components in them.
7. Relays can also be classified basing on their level of immunity to external AC voltages :
a) AC immunized- Relays
b) Non immunized Relays
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SYMBOLS AND NOMENCLATURE OF RELAYS AND WIRING PRACTICE:
The power signalling systems on our railways follow two practices:
(1) The British Railway practice and
(2) The Continental or German practice.
These two systems have an individual language of symbols and nomenclature .However they have a few common elements also
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MEANING OF LETTERS USED IN SYMBOLS
AND NOMENCLATURE
Letter Description
A Approach, automatic
B Block, Bolt
C Checking or proving
D Clear (green)Decoding
E Light: heat (externally applied)
F Fog
G Ground, gate, signal aspect H Caution (yellow)
I Indicator J Time (delayed action)
K Indicating or detecting
L Locking, left,
M Magnet 8/21/2020 S19 Relays and cables 18
MEANING OF LETTERS USED IN SYMBOLS
AND NOMENCLATURE
Letter Description
N Normal (push button or key)
O Retarder
P Repeater
Q Treadle or bar
R Reverse, right, red
S Stick
T Track circuit
U Route
V Train stop
W Point
X Audible indicator
Y Slotting
Z Zone, Any special term defined 8/21/2020 S19 Relays and cables 19
N Switch / Knob Contact in Normal Position
Switch / Knob Contact in Reverse PositionR
Relay Coil (Name of Relay is written inside the rectangle)R1 R2
DescriptionSymbol
Closed Contact when Relay is in Energised condition
Slow to release Relay
Slow to pickup Relay
Double Coil Relay
R1 R3
A C Immunised Relay
Time Element Relay front Contact (Energised Condition)
Flasher Relay contacts
NORMAL / REVERSE Contacts
(Front Contact)
(Back Contact)Closed Contact when Relay is in de-energised condition
R2 R4
Time Element Relay front Contact (de-Energised Condition)
R
N(3-Position Polar Relay) (Dependant type)
N NORMAL Contacts (Energisation on NORMAL side)
(3-Position Polar Relay) (independant type)
R REVERSE Contacts (Energisation on REVERSE side)
(3-Position Polar Relay) (independant type)
D De-Energised Contacts
(3-Position Polar Relay) (independant type)
NORMAL Contacts
R (2-Position Polar Relay) (independant type)
REVERSE Contacts
R
N
N
NORMAL / REVERSE Contacts
(2-Position Polar Relay) (independant type)
(2-Position Polar Relay) (Dependant type)
S.No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Symbols for british practise
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N Switch / Knob Contact in Normal Position
Switch / Knob Contact in Reverse PositionR
Relay Coil (Name of Relay is written inside the rectangle)R1 R2
DescriptionSymbol
Closed Contact when Relay is in Energised condition
Slow to release Relay
Slow to pickup Relay
Double Coil Relay
R1 R3
A C Immunised Relay
Time Element Relay front Contact (Energised Condition)
Flasher Relay contacts
NORMAL / REVERSE Contacts
(Front Contact)
(Back Contact)Closed Contact when Relay is in de-energised condition
R2 R4
Time Element Relay front Contact (de-Energised Condition)
R
N(3-Position Polar Relay) (Dependant type)
N NORMAL Contacts (Energisation on NORMAL side)
(3-Position Polar Relay) (independant type)
R REVERSE Contacts (Energisation on REVERSE side)
(3-Position Polar Relay) (independant type)
D De-Energised Contacts
(3-Position Polar Relay) (independant type)
NORMAL Contacts
R (2-Position Polar Relay) (independant type)
REVERSE Contacts
R
N
N
NORMAL / REVERSE Contacts
(2-Position Polar Relay) (independant type)
(2-Position Polar Relay) (Dependant type)
S.No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
Symbols for british practise
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British relays and Nomenclatures
Sr No Name Description
1 TSR Track stick relay
2 UCR Route checking relay
3 ASR Approach stick relay
4 WLR Point lock relay
5 WNR Point normal (operation ) control relay
6 WRR Point reverse (operation ) control relay
7 NWKR Normal point ( position ) indication relay
8 RWKR Reverse point ( position ) indication relay
9 TRSR Track right stick relay
10 TLSR Track left stick relay
11 SMCR Station master’s control relay
12 UYR1,UYR2 Sequential route release relays
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CIRCUIT IN BRITISH PRACTICE
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(Top Relay) Interlocked Relay Reverse Coil
Neutral Relay
Symbol Description
Interlocked Relay Normal Coil (Bottom Relay)
Track Relay
Track Repeater Relay
Block Relay in Automatic Territory
Time Element Relay T
Indicates that a Neutral relay is normally energized
Indicates that a Neutral relay is normally de energized
Indicates that an Interlocked relay is normally latched
(Normal coil)
(Reverse Coil) Indicates that an Interlocked Relay is normally de
latched
Make Contact
Break Contact
Make contact of a Neutral Relay that is normally picked up (Front Contact)
Break contact of a Neutral Relay that is normally picked up (Back Contact)
Make contact of a Neutral Relay that is normally drop (Back Contact)
Break contact of a Neutral Relay that is normally drop, (Front Contact)
Make contact of a Interlocked Relay that is normally latched, (Front Contact)
Break contact of a Interlocked Relay that is normally delatched (Back Contact)
Make contactof a Interlocked Relay that is normally delatched (Back Contact)
Break contact of a Interlocked Relay that is normally delatchedt (Front Contact)
S.No.
19
18
17
16
15
14
12
13
11
10
9
8
7
5
6
4
3
2
1
21
20
Symbols used in Siemens Practice
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Siemens Interlocked Relay Symbols
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Nomenclature of Siemens Relays
RELAY NOMENLATURES
GNR Signal button relay
GNCR Signal button checking relay
SH-GNR Shunt signal button relay.
CO-GGNR Common button relay for calling-on
signals
EGGNR/ERNR Common button relay to replace any
signal at 'ON"
UNR Route Button relay.
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Nomenclature of Siemens Relays
RELAY NOMENLATURES
UNR Route Button relay.
UNCR Route button checking relay
EUYNR Emergency sub-route release button
relay.
EUYZ Emergency sub-route release
operation counter.
EUUYNR Emergency ( full ) route release
button relay.
EUUYZ Emergency (full ) route release
operation counter
EUUYNCR Emergency (full ) route release button
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Nomenclature of Siemens Relays
RELAY NOMENLATURES
EUYR Emergency route release relay
( common for sub route and full route cancellation)
WNR Point button relay.
WNCR Point button checking relay
WWNR Common point button relay.
(when point zone track circuits are up)
EWNR Emergency Common point button relay
(when point zone track circuit is down)
EWZ Emergency points operation counter 8/21/2020 S19 Relays and cables 28
Nomenclature of Siemens Relays
WLR Point locking relay
WJR Point time delay relay
WR Point contractor relay (heavy duty contractor relay)
CHYNR Crank handle slot release button relay.
CHYRNR Crank handle slot return button relay
CHKLR Crank handle key lock relay.
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Siemens Circuits
CCT-1(SHT- 5)
S12 GN
S12 GNR
S12 EGNR
CCT-5(SHT-7)
5B Z1UR1
LL1 UNPR
S3 GNPR S12 GNPR
2 /3T UNPR LL2 UNPR
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Terms connected with Relays
1. Non-fusible contacts: A pair of contacts in which one contact element comprises of non-fusible material, which presents practically no risk of welding of contacts.
2. Carbon contacts: 'carbon' in the expression 'carbon - to- metal contacts' is used as a general term covering graphite and compounds and mixture of carbon and metals.
3. Metal contacts: 'Metal' in the expression 'metal to metal contacts' is used as a general term covering the use of silver, silver cadmium oxide, tungsten, platinum or any other suitable material to an approved specification.
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Terms connected with Relays
4. Front contact: That contact which is made with 'arm contact' when the relay is energized.
5. Back contact: That contact which is made with 'arm contact' when the relay is de-energized.
6. Arm contact: That contact which is movable part of the pair of contacts and is made with front contacts when the relay is energized and with back contact when the relay is de-energized.
7. Arm: The movable part of the pair of contacts.
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Terms connected with Relays
• Dependent contact – a movable arm contact connects to a FC when relay is energized and the same arm contact connects to a back contact when the relay is de-energized (4F/B)
• Independent contact – the condition in which the movable arm contact connects to either a front or a back contact and not to the both (2F,2F/2B)
• Pick up value – the value of current just enough to close all front contacts under specified conditions
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Front contact
Arm contact
Back contact
DEPENDENT CONTACTS
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Front contact
Back contact
INDEPENDENT CONTACTS
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Terms connected with Relays
10. Contact element: Contact piece, which is secured to a contact spring.
11. Wiping (self-cleaning) contacts: Contacts designed to have certain relative motion, during the interval from the instant of touching until completion of the crossing motion.
12. Contact follow: That distance which the movable arm contact travels after touching the front or back contact.
13. Contact bounce: means the uncontrolled making and breaking of the contact after it has closed first.
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Terms connected with Relays
Drop away/Release value - the value of current at which all front contacts just open
Operate – all front contacts just made
Full operate – the condition when armature has completed its maximum travel
Release – all front contacts just broken
Full Release – when armature returns back fully to stop postion
Percentage release = drop away/pick up x 100
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Operate Time (of )
(a) Back Contact: Means the time interval from the instant of application of the current to the coil until breaking of the back contact, which is the last to break.
(b) Front contact: Means time interval from the instant of application of the current to the coil until closing of the front contact which is the last to close and the contact bounce has ceased.
Release Time (of).
(a) Front Contact: Means the time interval from the instant of removal of energy to the coil until breaking of the front contact, which is the last to break.
(b) Back contact: Means the time interval from the instant of removal of the energy to the coil until closing of the back contact which is the last to close and the contact bounce has ceased.
Terms connected with Relays
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CHARACTERISTICS OF ELECTRO-
MAGNETIC RELAY:
The following are the important characteristics of electro-magnetic relays. Basing on these characteristics components and designs features of relays are decided .
Force of attraction
Effect of air gap.
Effect of Hysteresis
Transient condition.
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Force of attraction:
In any electro-magnetic system, the force of attraction is given by.
F B2 a
Where: B - is the flux density and a - is the cross sectional area of the particular part of the magnetic circuit.
Effect of air gap:
If the air gap is not available, then the residual magnetism fluxes might cause the armature to be retained when the supply is disconnected. For this reason, residual pins are provided to ensure a definite minimum air gap in the energised position.
CHARACTERISTICS OF
ELECTRO-MAGNETIC RELAY:
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Effect of Hysteresis:
Hysteresis is the property by which the flux produced lags behind the current. To overcome the effect of Hysteresis the relay core is made of material having high permeability and low retentivity
This reduces the difference between pick up value and Drop away value. By selecting good quality core material, Percentage release and sensitivity of the relay will be improve.
Transient Condition:
When the voltage is applied or disconnected from the coils, it takes some little time before the current become steady. These are known as transient conditions” and are important so far as track relays are concerned as they effect the release time of the track relay
CHARACTERISTICS OF
ELECTRO-MAGNETIC RELAY:
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To reduce releasing time to a minimum value
The relay iron should have low Hysteresis loss and low retentivity.
The degree of over energization of the relay should be restricted
Connecting a suitable external resistance in series with the relay to keep L/R ratio low.
CHARACTERISTICS OF
ELECTRO-MAGNETIC RELAY:
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Use relay with minimum contacts, as they require lesser current which keeps inductance value low
Train working safety is ensured only if the track relay of shortest length track circuit is released before a light engine running at a highest permitted speed clears it. Otherwise, the track circuit occupation may go undetected. To avoid this, a special provision has to be made in signal control circuits, wherever necessary.
CHARACTERISTICS OF
ELECTRO-MAGNETIC RELAY:
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ELECTROMAGNETIC RELAY
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Q-SERIES RELAYS
Presented By P.Shakila IOS5
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Plug-in type DC Neutral Line Relays ( Non –Proved type )
The Plug-in type DC Neutral Line Relays which suit to the BR specifications and used over Indian Railways are known as Q-series relays.
No separate IRS specification issued for these relays .But they confirm to IRS spec no. S23 and S34 ( for testing procedures).
They are known as non –proved type because unlike proved type relays their last deenergised state need not be proved when ever they are reenergized ,
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Base
Heel
piece
Electromagnet Non-magnetic
residual pin
Armature
Handle
Pusher
spring
Transparent
cover
Adjustment
card Operating
arm
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Constructional Features of the q-series Dc neutral relay
Standard common plug board with coding pin arrangement is used to prevent a wrong relay being plugged.
Each relay is provided with 5 coding pins and accordingly 5 holes (out of 10 i.e. A,B,C,D,E,F,G,H,J,K) are drilled in the plug board. These are known as code numbers. No electrical connection establishes between relay and plug board until code pins engage correctly. Six more code pin positions exist (L,M,N,X,Y,Z) which are used for special relays.
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Connectors, which are positively locked in to the plug board and can be with drawn by a special tool to permit easy disconnection.
Means for terminating permanent wiring to plug board on the connectors both by crimping & soldering.
Registration device with specified coding
combination in order to prevent a wrong relay being
plugged.
Constructional Features of the q-series Dc neutral relay
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No electrical connection possible between plug board and the relay base until code pins have correctly engaged
Fixed contact positioned by adjustment cards and moving contact positioned by operating arm drive by the armature.
Provision of helical spring to provide definite back contact pressure and aid in return torque.
Provided with Non-proved (metal to carbon contacts) and all are independent contacts only.
Constructional Features of the q-series Dc neutral relay
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Constructional Features (coding pins)
QN1 12F/4B
ABCDE
QN1 8F/8B
ABCDF
QNA1 12F/4B
ABDFH
QNA1 8F/8B
ABDGH
QLI
ABDEG
QBA1 12F/4B
ABFGH
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Constructional Features (coding pins)
QBA1 8F/8B ACDEH
QS3 (12V, 1000 ohms)
CDEKX
QT2 DEFJX
QTA2
FGHKX
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Constructional Features
Conform to IRS: S 23 & S 34, besides relevant BRS specification
Plug-socket type of inter-connection between relay and plug board
Retaining clip to hold relay firmly to ensure firm electrical connections.
All contacts are independent and non-proved type
Permanent wiring on plug board is terminated after proper crimping and soldering of wires on the connectors
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Constructional Features
Connectors are positively locked in plug board and at the same time they can easily be withdrawn with the help of a special tool in case of need
Fixed contacts are positioned by adjustment cards and moving contacts are positioned by the operating arm driven by the armature.
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Constructional Features
A non-magnetic residual/stop pin on the face of armature helps to reduce the effect of hysteresis/residual magnetism
A helical pusher spring helps to restore relay to full released condition and helps back contacts make properly when relay is de-energized
All moving arm contacts are silver contacts and all fixed front and back contacts are of silver impregnated graphite (non-fusing).
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NML
ZYX
FIG : 4.3
KJ
HGFE
DCBA
ABCD
1
2
3
4
5
6
7
8
R1
R3R4
R2
8
7
6
5
4
3
2
1
Interchangeable contacts
B5B6, B7B8
C5C6, C7C8
Front contacts
A1A2, A3A4
B1B2, B3B4
C1C2, C3C4
D1D2, D3D4
Back contacts
A5A6, A7A8
D5D6, D7D8 6/4/2020 S19 Relaya and cables 57
Standard Contact Arrangements
Q-series relays are provided with a maximum of 16 numbers of independent contacts. The standard contact configurations for various types of relays are: Line Relays – 12F/4B, 8F/8B, 8F/4B, 6F/6B 6F/2B, 4F/4B Track Relays – 2F/1B, 2F/2B ECRs (Lamp Checking Relays) – 3F/3B, 4F/4B * All the front and back contacts are “independent”. FC - “metal-to-carbon”, BC - “metal-to-carbon”.
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Contact Configurations
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TYPES OF Q-SERIES RELAYS
QN1 QNN1 QNA1 QNA1K QS3 QSA3 QB1 QBCA1 QSPA1 QSRA1 QL1 QJ1
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QN1 Relay
This is the fundamental Q series relay. All other relays of the Q series have been developed around the QN1 in order to standardize the components.
Iron circuits and contact stacks are mounted on a molded base of extremely stable non-hygroscopic thermosetting plastic (A thermo set material cannot be melted and re-molded).
Rated life of a relay is 1000000 cycles
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QN1 Relay
Contact springs are made of wear,corrosion & fatigue resistant phosphor bronze which extend beyond the base.
Armature pivots on a phosphor bronze plate riveted to the heel piece.
The magnetic circuit consisting of L shaped heel piece, electromagnet (core & coil) and armature are fixed to the thermosetting base below the contact stacks
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QN1 Relay
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Applications and Contact Configuration QN1 Relays
Contact Configuration – 12F/4B, 8F/8B, 8F/4B, 6F/6B, 4F/4B Applications – All circuits in non-electrified sections and internal circuits in electrified sections
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QN1 – Technical Data
Rated voltage : 24
Pick up voltage : 19.2 Volts
Coil resistance : 400 Ω
Drop away voltage : 3.6 V
Pick up time : 150 millisecond
Drop away time : 20 millisecond
Operating current : 60 mA
Spec : BRS 930A, IRS: S 23 & S 34
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QN1K Relay
QNN1 – DC Twin Neutral Line Relay
Conforms to BRS 960
It is a combination of two neutral relays with a common heel piece and a common base.
The two relays are independent and can be used for two different unrelated purposes.
Affects saving of space when requirement of number of contacts is less.
Equal number of contacts either 4F/4B or 6F/2B on both the relays
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QNN1
Coil resistance : 470 Ω
Rated/normal working voltage : 24
Pick up voltage : 19.2 Volts
Drop away voltage : 3.6 V
Application : all circuits in non electrified sections and internal circuits in AC electrified sections especially when number of contacts required is less and/or space constraint is there.
QNN1 – DC Twin Neutral Line Relay
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The relay is same as QN1 relay except that a copper slug is provided in this relay at the armature end of the core to achieve immunity against AC voltages.
When AC current passes through relay coil, the flux set up through air gap and armature is also linked with copper slugs. This induces eddy currents in copper slug the flux generated by which opposes the flux which caused the eddy currents in slug.
QNA1-AC Immunized DC Neutral Line Relay
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QNA1 – Technical Data
Pick up voltage : 19.2 Volts
Coil resistance : 208 Ω
Drop away voltage : 3.6 V
Pick up time : 220 millisecond
Drop away time : 70 millisecond
Operating current : 115-120 mA
AC Immunity level : 120 V AC 1- Phase 50 Hz
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QNA1 RELAY
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Applications and Contact Configurationof QNA1 Relays
Contact Configuration – 12F/4B, 8F/8B, 6F/6B, 4F/4B
Applications – All external circuits in electrified sections
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Provisions of Spec – IRS: S60-78 for AC Immunity Requirements
The relay shall not make by sudden application of 1000V 50 Hz AC
Relay not to break its back contact when1000Vrms is applied gradually or abruptly.
Maximum P.U transfer and release transfer time not more than 200 m Seconds when relays energized with 80% rated voltage.
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QN1 QNA1
Pick up voltage – 19.2 V
Pick up voltage – 19.2 V
Drop away voltage – 3.6 V
Drop away voltage – 3.6 V
Coil resistance – 400 Ω
Coil resistance – 208Ω
Operating current – 60 mA
Operating current – 115 mA
Pick up time – 150 msec
Pick up time – 220msec
Drop away time – 20 msec
Drop away time – 70 msec
Suitable for internal ciruits of RE area
Suitable for external circuits of RE area
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DC Neutral Sensitive Line Relay QS3
It is a sensitive relay designed to work on low voltage and
current.
Conforms to BRS 930
It was introduced with a drive to replace shelf type relays
Contacts are silver impregnated graphite to silver
Technical Data of QS3 Relays
Working voltage : 12V
Coil resistance : 1000 Ohms
Contact configuration : 4F/4B
Operating current : 12mA
Pick up voltage : 7.5-9.35 V
Min drop away voltage : 3.75 V
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QS3 Relay
Applications of QS3 Relays
Its application in most of the zonal railways started with the drive to do away with shelf type relays from axle counter circuits for safety reasons.
Accordingly 12 Volt version is being used as evaluator relay (EVR) and supervisory relay (SUPR) in analog axle counters to suit output of axle counter cards.
24V as well as 12V versions are being used for inner distant, distant and IB circuit applications in non-electrified sections where voltage drop becomes critical.
DC Neutral Sensitive AC Immunized Line Relay QSA3
Conforms to BRS 931A
Contacts are silver impregnated graphite to silver
It is primarily for use over long supply lines
A copper slug at the armature end of the core provides AC immunity.
Technical Data & Applications of QSA3 Relays
Working voltage : 12V / 24V
Coil resistance : 1000 Ohms
Contact configuration : 4F/4B
Operating current : 12mA / 24mA
Application : 24V as well as 12V versions are being used for inner distant, distant and IB circuit applications in electrified sections where voltage drop becomes critical.
DC Biased Neutral Line Relay QB3
This relay is sensitive to the polarity of the DC supply and operates only when rated DC supply of correct polarity is applied across its coil.
The armature does not get attracted even when a supply 20 times its rated voltage is applied in reverse polarity.
This biasing feature is attained through a permanent magnet fixed on the core.
DC Biased Neutral Line Relay QB3
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DC Biased Neutral Line Relay QB3
DC Biased Neutral Line Relay QB3
Neither electromagnetic coil flux nor permanent magnet can hold the armature in attracted position on their own.
The armature gets attracted and remains attracted only when both the fluxes act together to get added up.
Technical Data & Applications – QB3 Relays
Rated voltage and current – 12V DC, 60mA
Coil resistance – 200 ohms
Contact configuration – 4F/2B
Pick up current – 45 mA
Pick up/drop away time – 380/20 millisec.
Applications of QB3
Being biased, two relays can be worked on a single pair of conductors - thus saving a pair of conductors.
These are used in Podanur make single line block instruments as code receiving and checking relays.
The instrument contains 36 relays, 3 of which are QB3 type. These are named CRR(N), CRR(R) and TCKR (Transmission Code Checking Relays).
These instruments are able to work on a single pair of conductors because of these relays.
QBA1- Q series Biased & AC Immunized Relay
To make the relay AC immunized, copper slug is provided at its armature end adjacent to the permanent magnet.
Coil resistance – 200 ohms Working voltage – 24V DC AC Immunity – 1000V AC Pick up/drop away voltage – 19.2/3.6 V
Application – this also affects saving of one pair of conductors and is used in Daido single line block instruments (NR, BLR).
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QBA1 Relay
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QBA1 Relay
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QBCA1 Relay
Biased AC immunized relay with heavy duty front contacts
It has 2 heavy duty front contacts and 4 normal rating current rating back contacts.
Heavy duty front contacts are rated for 30 Amps.
Magnet pieces are held close to the heavy duty contacts and they blow or disperse the electric arc before it has a chance to grow and burn.
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QBCA1 Relays
Immune to 1000V AC The armature does not get attracted even when a supply 20 times its rated voltage is applied in reverse polarity. Conforms to BRS 943 & 966 Two extension springs behind the base are joined with front contacts and their springs so that 2 wires can be connected for sharing heavy load currents through these contacts.
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Contacts are silver impregnated graphite to silver Minimum front contact pressure is 56 gms as against 28 gms for other similar metal-to-carbon relays.
Two natural magnet pieces called magnetic called Blow out magnets are fixed on a bracket by the side of front contact elements .Spark quenching by these magnets during operation makes it possible for them to carry heavy currents
QBCA1 Relays
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Technical Data & Applications – QBCA1 Relays
Rated voltage and current – 24V DC, 120mA Coil resistance – 208 ohms Contact configuration – 2F(heavy duty)/4B Pick up/drop away voltage – 19.2/3.6 V
Application – The relay is designed primarily for control of point machines in AC electrified sections.
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Technical Data & Applications – QBCA1 Relays
Rated voltage and current – 24V DC, 120mA Coil resistance – 208 ohms
Contact configuration – 2F(heavy duty)/4B
Pick up/drop away voltage – 19.2/3.6 V
Application – The relay is designed primarily for control of point machines in AC electrified sections.
1) Permanent Magnet
2) Copper slug
3) Blow out magnets
QBCA1 Relay features :
QBCA1 Relay HD Contacts
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QBCA1 Relay HD Contacts
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QSPA1-Slow to Pick up Relay
Conforms to BRS 933A Magnetic shunt at the armature end makes the relay slow to pick up. The flux passes through the shunt initially and the relay picks up once the magnetic shunt saturates. Copper slug at heel piece end provides AC immunity.
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QSPA1 RELAY
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Slow to Pick up Relays
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Application, Technical Data-QSPA1
Used as TPRs in RE areas to avoid unsafe situations in cases of OHE snappings.
Pick up time – 540-600 millisecond Release time – 140-200 millisecond Working voltage -24v DC Coil resistance – 208 ohms Contact configuration – 8F/4B AC immunity level – 1000 v AC
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QSRA1-Slow to Release Relay
Conforms to BRS 934A Magnetic shunt at the heel piece end makes the relay slow to release. Saturated magnetic shunt helps to maintain the flux for a while as supply to the coil is cut off. Copper slug at heel piece end provides AC immunity.
QSRA1 RELAY
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Slow to Release Relays
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Application, Technical Data QSRA!
Used as HPRs, DPRs in RE areas to make them insensitive to momentary supply fluctuations and momentary track relay dropping, ECRs, button failure/point failure/signal failure indication relays etc DA time – 260 millisecond Working voltage -24v DC Coil resistance – 208 ohms Contact configuration – 8F/4B AC immunity level – 1000 v AC
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QL1-Magnetic Latch Relay
A permanent magnet at the heel piece end keeps it latched in the operated position.
No residual pin – requires power supply for releasing the relay
Reverse/operating coil – 150 ohms (to operate) and normal/release coil – 680 ohms (to release).
The two coils are wound on the same core but in the opposite directions. Feed to the operating coil is cut by the back contact of repeater relay.
Feed to normal coil is cut off internally with the help of a front contact as prolonged feed may demagnetize the permanent magnet.
QL1
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QL1-Magnetic Latch Relay
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Applications of QL1 Relay
TCFR, TGTR, TAR and TOLAR relays in Podanur make push button block instruments
Working voltage --- 24 v DC
In point circuits to prove correspondence Available in 11F/4B and 8F/6B configurations
QJ1 Relay Constructional Details
It contains a heating element (TH) and a DC neutral relay
( JSR) which combine together and operate an external relay after a preset time.
Heating coil is wound over a bimetallic strip of invar (an
alloy containing 64% iron and 36% nickel) at top and brass at bottom.
Invar has the lowest thermal expansion of any known metal or alloy from room temperature up to 230°C
QJ1 Relay Operating Principle
When heated, brass expands more as compared to invar and the bimetallic strip bends upward as one end of the strip is fixed.
This movement causes a set of contact to make (hot contact) after a predetermined time.
Closing of hot contact causes internal neutral relay (JSR) to pick up, which in turn cuts off the feed to the heating coil.
QJ1 Relay Operating Principle
.There by supply to TH coil is stopped. After some time, the heating element cools off and its arm closes with the cold contact. This cold contact in series with a 'JSR' front contact extends feed to an external relay (JR).
The complete cycle of making a hot contact and then a cold contact ensures that the thermal contacts are normalized before each operation. This in turn results in the time delay being equal for all operations.
In this relay, the time lapse during the 'cool off’ of the heating element is thrice the time lapse during its heating.
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QJ1-Relay
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QJ1-Relay
TPRA1
1
BD TH*
* NOT REQUIRED WHERE THERE
IS NO APPROACH TRACK
TH(HOT)
JSR
JSR
TH(COLD) JSR
JR
NEUTRAL RELAY
JSR
QJ1-Relay
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Electronic Timer Relay
Siemens Relays
Presented By P.Shakila IOS5
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K50 Relays DC Neutral Line Relays
Metal-to-Metal Contacts Proved Type
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K-50 Proved Type Relays
These are metal to metal contact miniature plug in type relays . Manufactured by M/s Siemens As metal contacts are used they may get welded during operation due to sparking Hence to avoid any unsafe operation , these relays are made proved type. Proved Type – Before using its operated contact to control a function it is ensured that the relay was in released condition earlier. IRS Spec. S46/74
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K-50 Proved Type Relays
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Relay construction
As seen in the diagram, the contact springs are stacked below the yoke which extends beneath the core. The armature when de-energized rests against stop stirrup. A contact bar with pins on it is rigidly screwed to an extension of the armature. A pusher spring provided between the armature extension and the stop stirrup is compressed when the armature is attracted and helps during its release when the relay is de-energized.
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1 CONTACT BAR 7 HEEL PIECE
2 PRESSING AWAY SPRING 8.PLACE FOR RELAY TYPE MARKING
3STOP STIRRUP 9.SPRING SUPPORT
4 ARMATURE 10.CONTACT SPRING
5 RESIDUAL PIN 11.CONTACT RIVET
6 MAGNETIC CORE 12.CONTACT PIN
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K-50 Proved Type Relays
Contact
bar
Pusher
spring
Magnetic
core Armature
Contact spring Spring
support
Contac
t pin
Contact
rivet
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General Characteristics of K-50 Relays
Plug-in, Proved type DC Miniature Relays
Independent Type of contacts (Max 8 Nos )
PU Time : 25- 60 m sec; Drop away time : 7 – 15 m sec.
(For AC immunized relays : 200 m sec / 50 m sec)
60V Operation (Range : 50-110V)
Contact resistance – 0.05 Ohm
Guide pins to prevent inverse plugging
Code pins to prevent plugging of wrong type
Contact current rating : 3 A Continuous, 5 A for 30 sec (SW)
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General Characteristics of K-50 Relays
Relays are available in form of groups (Mini, Minor, Major ). Metal to metal contact resistance is very less hence more number of contacts can be used in one circuit. To reduce arcing –1)Series double break double make contacts are used, and 2) the elliptical shape of the contact element and cylindrical shape of contact pins provides less contact area.3)Wiping action of contacts also called as self cleaning. Standard contact arrangement – Front 2 3 4 6 5 4 Back 2 3 2 2 3 4
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Relays are classified as: A type, B type and E type on the basis of
thickness of residual pin/separating pin. (a) K50-A type: (0.35 mm residual pin
thickness). Non ACI Neutral, Interlocking Relays. (b) K50-B type: (0.15mm residual pin
thickness). ACI Neutral and UECR (c) K50-E type: (0.45mm thickness). ON ECR and OFF ECR
Classification:
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Construction, General Requirements
If a back contact remains closed accidentally, none of the front contacts shall close even at a supply voltage of 1.5 times the rated voltage.
If a front contact remains closed accidentally, all other front contacts must open and none of the back contacts should close.
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K50 Neutral Relay Mini-groups
Two K50A relays with eight contacts each are fixed one below the other on a frame fitted into a back plate.
Contact springs and coil ends of relays are connected separately by wiring to two spring blocks with springs extending behind.
These springs get joined with corresponding smug fitting spring terminals on two amphenol blocks fixed on a base plate when plugged.
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K50 Neutral Relay Mini-groups
External wiring is soldered on the terminals behind the base plate.
Two thick pins each on the blocks of group back plate enter into corresponding holes on base blocks and ensure correct alignment.
They also prevent relay group being plugged upside down.
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Mini group Relay- View showing coils & contacts
CLASSIFICATION OF MINI GROUPS
MINI GROUP
NEUTRAL AC IMMUNISED INTERLOCKED ECR”S
6F/2B
5F/3B
4F/4B
BOTH
IMMUNISED
ONLY TOP
IMMUNISED
6F/2B
5F/3B
4F/4B
ONECR
OFF ECR
UECR
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Group Coding in Mini groups :
Two code pins are provided, one at the top and one at the bottom screwed onto the base plate .
These code pins have 8 different positions( Four at the top and four at the bottom ) .They enter into corresponding holes in the back plate of the relay group when a proper group is plugged in to the base.
These code pins ensure that only a group with a similar contact configuration can be plugged in a base.
Three different codes can be found for the three contact arrangements of these groups.
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Code pins positions for different relay groups :
(a) Neutral:
5F/3B (1260 ohms) 1 & 6
4F/4B (1260 ohms) 1 & 7
6F/2B (1840 ohms) 1 & 5
(b) Inter Locked:
4F/4B (615 ohms) 3 & 7
5F/3B (615 ohms) 3 & 6
6F/2B (615 ohms) 3 & 5
Relay base for
Mini group
Guide pin
Guide pin
Code pin hole
Code pin hole
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Coil resistance:
Neutral relays: 5F/3B and 4F/4B: 1260 ohms, 6F/2B: 1840 ohms, Interlocked relays: All contact configurations: 615 Ohms. (More current is required for the operation of interlocked relay to overcome friction of latch pieces). Lamp checking relays: 64.1 ohms. (UECR, ON / OFF ECR).
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AC immunized Relays:
Uses copper slug for AC immunization A Brass strip is provided on contact bar to reduce the release time. This acts as counter weight on the armature. Immunized to 450 V AC Coil resistance 1840 ohms. (All contact combinations) PU time: 200 msec. DA time: 50 msec.
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INTERLOCKED RELAYS
Two neutral K-50 relays are latched mechanically to form an interlocked relay. Top coil is called Reverse coil and bottom coil is called as Normal coil.
Latch pieces are provided on the contact bar of a top relay and on the armature extension of a bottom relay.
A guide bracket is provided to keep the relay in alignment. Front contact of the R coil is proved in the pick up circuit of the N coil externally so that the supply is automatically cut off.
This helps to save power. Hence this is called as Economizer contact.
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UTLISATION OF INTERLOCKED RELAY
a) Work As A Memory Device To Detect The Last Operation,because It Remains Picked Up In The Last Operated Position.
b) It Is Also Used To Achieve Direct Interlocking Between Two Conflicting Function Such As …..
1.SHUNT AND MAIN SIGNAL PROVIDED ON THE SAME POST Ie SH-G(R/N)R
2.Direction Determining Relay Used To Lock Two
Conflicting Signals. Zu(r/N)r
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INTERLOCKED RELAY:
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Contacts
Max no. of contacts is 8 in Neutral and Interlocked relays a In ECR there are 6 contacts only. Total terminations: 8 X 2 Contact + 2 X 2 Coil terminations=20 for one k50 relay. For a mini group 40 terminations are required For 4 mini group relays will mean 160 terminations, hence a 160 way tag block is used for terminations and. For 5 numbers of mini groups can be accommodated in one 200 way tag block.
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Standard Contact configuration:
Neutral and Inter Locked 6F/2B, 5F/3B, 4F/4B ECRs (ON/OFF) 3F/3B. UECR 5F/1B. Contact current rating is : 5 A continuous and 3A switching.
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Neutral and Interlocked relay
4F/4B configuration
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4F/4B configuration
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Neutral and Interlocked relay
5F/3B configuration
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5F/3B configuration
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Neutral and Interlocked relay
6F/2B configuration
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6F/2B configuration
TERMINATION DETAILS
Contact nos. Rear view - Termination details
Left column
(Bottom relay)
Right column
(Top relay)
11 94 (c) 93 92 (c) 91
12 84 - - 83 82 - - 81
13 74 - - 73 72 - - 71
14 64 - - 63 62 - - 61
15 54 - - 53 52 - - 51
05 44 - - 43 42 - - 41
04 34 - - 33 32 - - 31
03 24 - - 23 22 - - 21
02 14 - - 13 12 - - 11
01 04 -Sp- 03 02 -Sp- 01
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TYPES OF MINI GROUP (LINE) RELAYS & CONTACT CONFIGURATION
Control Relays Lamp Proving Relays
Neutral Interlocked ECRs
Non
ACI
ACI Both
Non-
ACI
One
ACI,
One
Non-
ACI
Both
ACI
On Off Route
6F/2B
5F/3B
4F/4B
5F/3B 6F/2B
5F/3B
4F/4B
5F/3B 5F/3B 3F/3B 3F/3B 5F/1B
ECRs
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ON ASPECT ECR
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OFF ASPECT ECRS
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UECR
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Item K-50 Q-Style
Contacts Metal to metal Metal to Carbon
Operation 60V 24V
Current 33 mA – 50 mA 60 mA
Configuration 6F/2B,5F/3B,4F/4B 12F/4B,8F/8B
Coil-R 1840/1260 Ohm 400 Ohm
PU Time 25-60 m sec 150 m sec
DA Time 7-15 m sec 20 m sec
Contact R 0.05 Ohm 0.2 Ohm
Contact rating 5A/3A 2A/3A
COMPARISON OF K-50 & Q-STYLE RELAYS
Tag block
100 way(96)- panel wiring
160 way -4 nos of mini group
200 way –one major group, 2 minor group,5 nos of mini group
Lamp checking relays
Presented
by
P.Shakila IOS5
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Lamp Checking Relays
Lamp proving Relays are current sensing D.C. line relays
They operate by power drawn from the A.C. signal lamp
circuits
A current transformer is usually connected in series with the
signal lamp circuit.
The output of this current transformer is fed to a bridge
rectifier, which in turn feeds the lamp checking relay.
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Purpose of ECRs
To provide a cascading arrangement.
To provide a Red lamp protection arrangement
Controlling the signal in accordance with the aspect
displayed on signal in advance.
(To provide a signal aspects indication at the
operating place.
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Methods adopted for repeating the
signal aspects
Using a series resistance usually known
as potential drop method
Using a current transformer method.
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RGKE
D1-D4
1000
HECR
RG
HG
NX110
110/12 V
BX110 HR 110/12 V
HR
A)Potential drop method 1
When the signal lamp is lit a potential about 10 V is obtained
and this is used for light up the indication lamp connected
across the resistor. The draw back of this method is greater
drop in voltage for indication purpos
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RGKE
D1-D4
1000
HECR
RG
HG
NX110
110/12 V
BX110 HR 110/12 V
HR
A)Potential drop method 2
In the second method the voltage drop across the
variable resistor is rectified and the out put voltage
is utilised to operate a ECR relay. When the lamp
fuses, the current through the resistance decreases
and therefore the ECR relay drops.
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(B) Current transformer method
In this method a current transformer is connected in series
with either the primary or the secondary of the signal
transformer. The output of this current transformer is rectified
and connected to ECR relay . Again in this three different
methods are followed basing on the type of transformers
used
i) 'I' type current transformer.
ii) ‘L' type current transformer.
iii) 'H' type current transformer.
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Comparision of ECR relays
'I' type ‘L' type 'H' type
Usage For giving direct
indications at
cabins
To energise lamp
checking relay in
the ECR unit at
cabin or relay room
To energise lamp
checking relay in the
ECR unit at signal
and also for checking
main filament in
Triple pole lamps
Where connected In series with the
primary of the
signal transformer
In series with the
primary of the
signal transformer
In series with the
secondary of the
signal transformer
Current range 0.3A on the
primary
0.3 Amp on the
primary
2.5 Amp on the
secondary side
Voltage drop across
the load ( ECR or a
indication lamp )
7 volts 9V across 9V
Voltage ratio
Primary/ Secondary
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ECR RELAY
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Siemen’s ECRs
The Siemen’s ECR relays are supplied as mini groups. The mini
group comprises of a current transformer, bridge rectifier and a
neutral relay of K. 50 ‘E’ type.
There are three types of Siemen’s ECR relays
ON aspect ECR, OFF aspect ECR and UECR.
The ON aspect ECR de-energises when the main filament of a
signal lamp is fused and the auxiliary filament is intact, so as to
draw the cabin man’s attention . This helps early detection and
replacement of lamp and there by avoiding the possibility blank
signal. This consideration is not necessary for the OFF aspect.
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RECR Unit
When both filaments of the signal lamp are lit, the primary voltage of the current transformer is about 3.4V at 300 mA current. The relay gets a D.C. voltage of over 7V and picks up. When the main filament of signal lamp is fused, the primary circuit current falls to about 100 mA. The relay voltage drops to less than 2V, well below its drop away value. The relay drops.
Since the drop away value of this relay is above 4.5V, it drops even when the auxiliary filament of signal lamp is fused and main filament above is lit. 8/21/2020 S19 Relays and cables 173
DECR Unit
When both filaments of the signal lamp are lit, the primary voltage of this unit transformer is about 12.5V at 300 MA current. At that time the relay gets a DC voltage of about 9.6V.
When main filament is fused, the primary current falls to about 50 MA. The relay gets a voltage of over 5V which is more than its D.A. value. Hence the relay does not drop.
When both the filaments fuse, the no load current of signal transformer, which is less than 15 MA makes the relay to drop.
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Sl.no.
Description ON ECR OFF ECR
1 Current transformer voltage ratio
1 : 3 1:1
2 Amphenol terminal no’s of relay coil
1-91 1-92
3 Relay coil Resistance
64.1 64.1
4 Std contact configuration
3F/3B 3F/3B
5 PU voltage/current
App.5 V/<340 m A
App 9 v/<340 m A
6 DA voltage/current App.4V/125 m A
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SIEMENS UECR Unit
The primary of the current transformer is connected
in series with the signal lamp circuit.
Its secondary voltage is rectified by D1-D4 and
smoothened by condenser C1. This voltage is
applied to the ECR relay in series with an SCR.
The SCR switches on when its gate current is > 5
MA. Also, SCR has a constant voltage drop across it
irrespective of current through it.
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UECR Unit
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CT- Current Transformer
D1- D4- Bridge Rectifier
D5- To make relay slow to release
C1- Condenser -100 Mfd. Filtration of rectified PC
C2- Condenser - 0.1 Mfd
R1- Resistance = 33 K Ohms
R2- Resistance = 3.9 K Ohms to limit gate current
R3- Resistance = 10 Ohms to limit circuit current
UECR = K-50. 'B' Type relay
UECR CIRCUIT
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Polarised Relay
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DC Polarized Relay
It makes different contacts for different polarities of DC supply connected to it.
It works on the principle that the poles of electromagne8ts change with the direction of current.
Application –It is used in token block instruments to check line polarity when block handle is turned at the other end of the section.
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Operating principle of DC Polarized Relay
In this relay, a steel strap is polarized by a permanent magnet placed behind it and is hinged between the poles of an electromagnet.
A movable contact spring called 'arm' is attached to the strap in the front.
This Arm makes with one of the two fixed contacts on either side when the relay is energized with alternate supply polarities.
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Polarised relay
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Polarised relay
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Polarised relay
Reverse contact
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Polarised relay
Norma
l
contact
Operating characteristics:
a. Rated pick up value = 21 MA
b. Resistance = 77 ohms c. Drop away value = Not less than 50% of pick up value. d. AC Immunization = 10 V AC Permitted over energisation =25ma as per SEM para
22.9.10.2 Current carrying capacity of a contact - continuous = 1 Amp for 30 sec = 2 Amp f. Contact resistance = 0.25 ohms
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SIEMENS THERMO
FLASHER UNIT
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Principle of operation of Thermo Flasher unit
The thermo flasher unit is used to generate a flashing
supply to give flashing indications on the panel
An oscillating mercury column enclosed in a U-shaped
glass tube gives the periodical flashing of about 60
impulses per minute.
The movement of mercury column is caused by hydrogen
gas in an interconnected glass chamber. In the lower
portion of the gas chamber, a heating element is placed.
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Principle of operation of Thermo Flasher unit
When current is passed through the filament of heater, gas
expands and exerts pressure on the mercury column in one limb.
With depression of the column in one limb, the contact of the
heating element 'g/a' breaks.
The mercury column then returns to its original position by force
of gravity. Now, the heating circuit is closed again. This
procedure gets repeated and swings the mercury column
continuously till the external feeding circuit is opened. This
opens and closes the contacts b/a, c/a, d/a, e/a & f/a, alternatively,
which can be used for the required indication controls
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Flasher Relay
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Flasher Relay
Thermo Flasher unit
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Parameters of Thermo Flasher unit
1. Coil (heating circuit input)12V D.C/A.C or 110V/220V AC
(With built in transformer).
2. Approx. power input 9W @ 12V and
during heating impulse 20W @ 110/220V.
3. Flashing frequency 60/ minute.
4.Current on contact - 6A @ 12V, 2A @ 110V & 1A @ 220V.
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Track relays
Presented by P.Shakila IOS5
PLUG IN TYPE TRACK
RELAYS
1)Characteristics of relay
2)QT2
3) QTA2
4) QBAT
Factors that effect the sensitivity of relay :
a) Force of attraction
b) Effect of Air gap
c) Effect of Hysteresis
d) Transient condition
In any electro-magnetic system, the force of attraction is given by.
F B2 a
Where: B - is the flux density and a - is the cross sectional area of the particular part of the magnetic circuit.
But B is proportional to Current .So F α I2 .
This feature has got more effect on Track relay , because even a small change in current will have a great effect on the working of the relay
Force of attraction:
The difference between Pickup current and drop away currents of the relay should be as small as possible to ensure good shunting characteristics .
This can be achieved by maintaining a small air gap between core and armature
If the air gap is not available, then the residual magnetism fluxes might cause the armature to be retained when the supply is disconnected.
For this reason, residual pins are provided to ensure a definite minimum air gap in the energised position.
Effect of air gap:
Hysteresis is the property by which the flux produced lags behind the current. High hysteresis loss will increase PU time & DA time
To overcome the effect of Hysteresis the relay core is made of material having high permeability and low retentivity (i.e, low Hysteresis loss)
This reduces the difference between pick up value and Drop away value. By selecting good quality core material, Percentage release and sensitivity of the relay will be improve.
Effect of Hysteresis
The relay coil has certain amount of inductance which produces back emf during energising and de-energising of the relay.
This causes a transition in the relay current from reaching its maximum or minimum values . Due to this transition the pickup time and drop away time of relay are effected.
Transient conditions” are important so far as track relays are concerned as they effect the release time of the track relay
Transient Condition
How the percentage release & sensitivity of TR are improved
To reduce releasing time to a minimum value
• The relay iron should have low Hysteresis loss and low retentivity.
• The degree of over energization of the relay should be restricted
• Connecting a suitable external resistance in series with the relay to keep L/R ratio low.
• Use relay with minimum contacts, as they require lesser current which keeps inductance value low
• Train working safety is ensured only if the track relay of shortest length track circuit is released before a light engine running at a highest permitted speed clears it. Otherwise, the track circuit occupation may go undetected. To avoid this, a special provision has to be made in signal control circuits, wherever necessary.
QT2 Style Track Relay
• Similar in construction to line relay.
• Coil resistance: 4 Ohms and 9 ohms.
• 4 ohms relay is used for longer length track circuits and 9 ohms relay for shorter length track circuits.
• 2F/1B is to reduce load on armature, hence sensitive and can operate at low voltages.
• Back contact is used for cross protection to prevent the repeater relay from picking up in case of false feed.
QT2 Style Track Relay
• Maximum permissible excitation is 300% of the rated PU value. (Pusher spring allows higher excitation than shelf type). Minimum excitation is 125% of p.u.v
• % Release must not be less than 68%.
• Use: As TR in Non RE areas.
• 9 ohms relay: PU current: 103mA- 117mA, PU voltage: 1.5V.
• 4 ohm relay P U voltage: 0.3V to 0.5V.
QT2 Style Track Relay
QT2 Style Track Relay
QTA2: AC immunized track relay.
• In this relay, a copper slug is provided on the core at its armature end to make it immune to A.C.
• In all other respects, it is similar to QT2 relay in construction.
• Its coil resistance is 9 ohms, which can ensure A.C. immunity of not less than 50V.
• 20 ohms coil QTA2 relays are also available.
• Due to the provision of copper slug, the relay requires more DC operating power and it takes more time for its pick up and release.
QTA2: AC immunized track relay.
• Only QSPA1 relay is permitted to be used as TPR with this track relay.
• This is because an unsafe condition shall not be created during the catanery short circuit conditions, when A.C. voltage drop in a track circuit rail increases manifold, the TR may pick up under train and remain so for over 250 m sec.
• The circuit breaker in the traction power substation takes about 300 m sec. to trip.
• In this context, QSPA1 relay’s use as TPR is safer as it takes a longer time to pick up.
QTA2 AC immunized track relay.
• A/C Immunity level 50V AC rms.
• Contacts --- 2F/1B.
• Being sensitive relay its DC PU value should not change by a larger extent hence the limitation on the AC immunity, same as in shelf type.
• Max length of Track circuit is 450mtrs. (Rail voltage drop is 10V /90mtrs of track circuit).
• QSPA1 only is to be used as repeater relay with QTA2.
• 9 ohm relay: PU volts: 1.0 to 1.4V, PU current: 120mA to 140 mA.
QTA2 AC immunized track relay.
QBAT: Biased AC immunized Track Relay
• This is a track relay with an improved immunity level of 80V A.C. by the provision of a biasing permanent magnet on its core along with its copper slug.
• This biasing by initially polarizing the core strengthens its electro-magnetic flux created in the correct direction by coil current.
• This takes more AC voltage to disturb the DC working flux. • This relay also requires QSPA1 relay as its TPR for the same
reasons specified in the case of QTA2 relay. • Construction same as QBCA1 excepting for contacts. • Permanent M agnet is for biasing and also contributes to
raising AC immunity level. • Copper slug for AC Immunity.
QBAT: Biased AC immunized Track Relay.
• Contact configuration: 2F/2B.
• PU volts: 1.1 to 1.75V,
• PU current: 140mA to 175 mA.
• AC Immunity level : 80V,
• Coil resistance: 9 ohms.
• Max length of track circuit: 720mtrs and can be extended to 750mtrs by using a choke at relay end and feed end
• Maximum excitation: 235% of P.U.V only because of the flux of P.M.
QBAT RELAY
M Biasing magnet
L Copper sleeve
QBAT
Signalling cables
Presented by P.shakila IOS5
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SIGNALLING CABLES
PVC insulated PVC sheathed and armoured signalling
cables to specification IRS S63 shall be used for signalling
circuits.
The conductors used shall be of copper and of approved
size.
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SIGNAL CABLE LAYING PRACTICE
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TYPES OF SIGNALLING CABLES
1. INDOOR CABLES 2. OUT DOOR CABLES 3. POWER SUPPLY CABLES
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INDOOR CABLE OUT DOOR CABLE
POWER CABLE
INDOOR CABLES
1. Indoor cables are without armor wire 2. All the PVC insulated conductors are bunched and kept in thin
PVC insulation tubes
3. Available in 60C,40C,24C,20C &16Core cables S.
No Dia. of the conductor
Size of core Used
1 0.6 mm 60C,40,24C & 20C
Used for relay wiring
2 1 mm 60C,40,24C & 16C
Copper single stand used for high current circuits such as signal lamp circuit, point operation circuit, gate circuits, etc.,
3 0.4mm single stand
Flexible wires Copper single stand wire used for indication lamps and panel wiring.
4 16 stands 0.2mm
Flexible wires
Used for Q- Series relay wiring. 8/21/2020 S19 Relays and cables 219
1 2 3 4 5 6 7 8 9 10
Blue Red Grey Green Brown Black Yellow with
Red dots White Pink Violet
Indoor cable conductors can be numbered according to color
code as shown below:
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OUT DOOR CABLES (IRS . S63)
1. These conductors used are copper conductors having equal diameter with PVC insulation.
2. All the PVC insulated conductors are bunched and kept in PVC insulation tube.
3. On the circumference of this tube, Galvanized iron rectangular or circular cross section wires called armor is provided to give the mechanical strength to protect the cable from damages.
4. On the armor PVC insulated thick tube is provided to give the more mechanical strength and good insulation resistance in addition to preventing the water entering inside the cable.
5. Sizes of conductors: 1.5 sq.mm., 2.5 sq.mm. and 4 sq.mm. 6. Cables available in 2C, 4C, 6C, 8C, 9C, 12C, 18C, 20C, 24C and 30C.
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Core Color Layers
2C Red and Black
4C Blue, Black, Red and Yellow
12C Blue, Grey and Yellow Outer layer (9 conductors)
Blue, Red and Yellow Inner layer (3 conductors)
30C Blue, Grey and Yellow Outer layer (16 conductors)
Blue, Grey and Yellow Second layer (10 conductors)
Blue, Black, Red and Yellow Last layer (4 conductors)
7. Conductors bunched in the form of layers. 8. Numbering is started from outer most layers of conductors and
each layer numbering starts from Blue color, then Gray and layer end with Yellow.
OUT DOOR CABLES (IRS . S63)
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CORE ARMOUR
OUTER
SHEATH
METALLIC
SHEATH
INSULATION
PAPER
CORE
INNER
SHEATH ARMOUR OUTER
SHEATH
SCREENED CABLE
UN SCREENED CABLE
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Outer
Layer
1 2 3 4 5 6 7 8 9 10
Blue Grey Grey Grey Grey Grey Grey Grey Grey Yellow
Inner
Layer
10 11 12
Blue Red Yellow
1st Layer (Outer
most Layer)
1 2 - 15 16
Blue Grey Yellow
Outer Layer 17 18 - 25 26
Blue Grey Yellow
3rd Layer (Inner
Layer)
27 28 29 30
Blue Black Red Yellow
30
CORE
:
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Outer
Layer
1 2 3 4 5 6 7 8 9 10
Blue Grey Grey Grey Grey Grey Grey Grey Grey Yellow
Inner
Layer
10 11 12
Blue Red Yellow
12 CORE CABLE
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1st Layer (Outer
most Layer)
1 2 - 15 16
Blue Grey Yellow
Outer Layer 17 18 - 25 26
Blue Grey Yellow
3rd Layer (Inner
Layer)
27 28 29 30
Blue Black Red Yellow
30 CORE CABLE
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POWER SUPPLY CABLES
1. PVC insulated screened and armored cable to IRS. S35/1970. 2. Any metallic sheathed armored cable having a cable reduction
factor of not more than 0.4 at a field strength of 87.5 to 450 v/km
3. Paper insulated lead sheathed and armored IRS. E 17/1959. 4. Conductors are alluminium & copper.
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Dia. (sq.mm) Core
70 (Alluminium) Single strands 3 & 3½
50 (Alluminium) Single strands 3 & 3½
25 (Alluminium) Single strands 3 & 3½
25 (Alluminium) Multi strands (7) 2, 3, 3½ & 4
10 (Alluminium) Single strands 2
8 (Copper) Single strands 2
6 (Copper) Single strands 2
Cable Numbering: 01 24 (4) or 02 18 (4) or 03 24 (6) First two no’s indicates - S. No. Second two no’s indicates – Core In brackets indicates – Spare; M- main; T- tail; P- power cable
POWER SUPPLY CABLES
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LAYING OF SIGNALLING CABLES
All signalling circuits are transferred to underground cables.
Only un screened cable should be used.
Screened cable already existing to be continued.
The main cables shall ordinarily be PVC insulated and armored cable to IRS S – 63.
Insulation resistance of each core shall not be less than 5 Mega ohms/km at 50 degrees.
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LAYING OF SIGNALLING CABLES
PLANNING: 1. Determine number of conductors required. 2. Adequate spare conductors min. of 10% of the total conductors
used shall be provided in each cable 3. No spare conductors are required if the total number of
conductors used is three or less. 4. After deciding the size and the no. of conductors , a foot survey
along the track should be taken, as far as possible, to avoid water mains, oil pipes, drain/sewage pipes, water columns etc.,
5. Before starting the trench work approval shall be taken from P.WAY/ELECTRICAL departments.
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Width of cable trench 0.46 Mtrs.
The cable laid parallel to the track normally be buried at a depth of 1 Mtrs. from ground level.
In theft prone area depth of 1.2 Mtrs. with anchoring at every 10 Mtrs.
Out side the station limits, the cable should generally be laid not less than 8 to 10 Mtrs. from the centre of the track.
With in station limits, the cable shall preferably be dug at a distance not less than 5.5 Mtrs. from the centre of the track in RE area.
TRENCH
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With in station limits, the cable shall preferably be dug at a distance not less than 3 Mtrs. from the centre of the track in non- RE area.
When signalling and main telecom cables are laid in the same trench, a distance of 100 mm is to be maintained between them.
When signalling cables and LT or HT power cables are laid in the same trench, they must be separated by a row of bricks between them.
TRENCH
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The bottom of the cable trench shall be levelled and sharp materials, if any, shall be got rid of. In case of soft ground, the cable shall be laid at the levelled bottom. In case, the ground is rocky, the cable shall be laid on a layer of sand of 50mm thickness deposited at the bottom of the trench.
In both the above cases, the cable shall be covered with a layer of sand or "Sifted" earth of 100 mm thickness as a protection and provide bricks on the layer and filled.
TRENCH
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While cross the track
The cable crosses the track right angles.
The cable does not cross the track under points and crossings and
The cable laid in concrete or GI or PVC pipes or suitable ducts or in any other approved type.
While crossing track 1 Mtrs. below the rail flange.
Cables are to be laid with in 1Mtrs. from sleeper end, digging beyond 0.5 Mtrs. shall be done in the presence of an official from engineering department.
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When cable have to cross a metallic bridge, they should be placed inside a metallic trough which may be fitted, as an anti theft measure, with sealing compound. Adequate cable length to the extent of 2 to 3 Mtrs. shall be made available at the approaches of bridges.
Cable markers shall be provided at suitable internal at diversion points.
At each end of the main cable an extra loop length of 6 to 8 Mtrs. Should be kept.
For recognizing deferent cables in case of faults etc., the cable shall be laid in an order from track side.
Telecom cable. Signal cable. Power cable.
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While cross the track
ADDITIONAL PRECATIONS IN RE-AREA
1.AT OHE STRUCTURE:-
Cable depth does not exceed 0.5 Mtrs., cable trench should be 1 Mtrs. away from the OHE mast.
Cable depth exceeds 0.5 Mtrs., a minimum distance of 3 Mtrs. between the cable and the nearest edge of the OHE mast.
If it is difficult to maintain these distances, the cable shall be laid in concrete / HDPE / Ducts / any approved means for a distance of 3 Mtrs. on either side of the mast. Where so laid, the distance between the cable and the mast may be reduced to 0.5 Mtrs.
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2.Sub Station and Feeding posts
As far as possible, the cable shall be laid on the side of the track opposite to the Feeding post.
The cable shall be at least 1 Mtrs. away from any metallic part of the OHE and other equipment at the Sub station which is fixed on the ground and at least 1 Mtrs. away from the Substation earthing.
In addition, the cable shall be laid in concrete or heavy duty HDPE or split RCC pipes or other approved means for a length of 300 Mtrs. on either side of Feeding post.
ADDITIONAL PRECATIONS IN RE-AREA
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3. SWITCHING STATIONS
The cable shall be laid at least 1 Mtrs. away from
any metallic body of the station, which is fixed in the
ground, and at least 5 Mtrs. from the station earthing.
The distance of 5 Mtrs. can be reduced to 1 Mtrs.
provided the cable are laid in concrete pipes or
heavy duty HDPE or ducts or any other approved
means.
ADDITIONAL PRECATIONS IN RE-AREA
4. Where are independent earth is provided for an OHE structure i.e., where the mast is connected to a separate earth instead of being connected to the rail, the cable shall be laid at least 1 Mtrs. away from the earth.
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INSTALLATION
Testing cable before laying : 1. Visual inspection of cable. 2. Cable shall be tested for insulation and continuity. 3. The insulation resistance of new cable shall not be
less than 200 mega ohms per km. at 20 degree centigrade.
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INSTALLATION
Paying out the cable: 1. The cable drum shall be mounted on cable wheels. 2. The drum on the wheel shall be brought to one end of the trench
and laid in the trench. 3. The drum on wheel shall then be rolled along the road or track. 4. Wheel are not available, the drum shall be mounted on axle at
one end of the trench and cable payed out. 5. Cable should be carried by adequate number of men ensuring that
the cable is not damaged and no kink is formed.
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Testing Of Cables for Faults
The common faults which develop on conductors of multi-core signaling cables are: i) Earth ii) Short-Circuit iii) Open -Circuit.
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Earth fault develops in a conductor due to defective insulation, which allows the current, carried by the conductor to leak to the earth directly or indirectly instead of going to the apparatus to which the conductor is connected
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Earth fault
Short circuit occurs when a connection or short develops due to defective insulation between two or more conductors where no connection should exist.
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Open circuit: It develops if a break occurs in a conductor.
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Method of Testing with a Megger
Megger used for testing signaling cables is of 500 Volts DC. For telecom cables is of 110 Volts DC. All the above mentioned common faults which develop on conductors of multi-core signaling cables can be detected by testing with a megger.
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To Test for an Earth fault:
If the conductor to be tested in the use, both ends must first be disconnected from the circuit of which it forms part. One end is then connected to the megger terminal marked for line. The next step is to connect the other megger terminal E (EARTH) to a good earth. Then rotate the megger handle about 80 RPM and while doing this observe where the pointer comes to rest on the scale. If the pointer rests at ZERO, there is a full earth fault in the conductor.
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To Test for an Earth fault:
If it rests at INF (INFINITY), it indicates that the insulation of the conductor is O.K. When the megger handle is rotated a voltage is generated which tries to pass a current through the conductor. No current will flow, however, if the insulation is in order as the circuit is not complete. An earth fault, however, will complete the circuit and a current will then pass through the circuit
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To test for a short circuit.
The conductors if in use, must first be disconnected. Then connect them to and rotate the megger handle. It will megger be obvious from the diagram that, if there is no connection between the conductors, no current can flow, and the pointer will come to rest at INFINITY. If, however, the conductors are in contact, a circuit is formed, and the current will cause the needle to indicate ZERO.
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To Test for an Open Circuit:
This test can be made in two different ways. One is made by using an earth return, and the other is made by using another conductor known to be o.k. When using an earth return, first connect one end of the conductor to the megger terminal L. Then connect the other megger terminal to good earth. The far end of the conductor should also be connected to a good earth If a second conductor is used to make the test, connect up In both cases, if the conductor under test is unbroken, a circuit is formed, and, when the megger is operated, the pointer will indicate ZERO. Should, however, the conductor be broken the pointer will indicate INIFINITY.
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1
2 2
1SHORTLE
LE
E
BREAK WIRE
OROPEN CIRCUIT
LE
OPEN CIRCUIT
BREAK WIRE
OR
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Testing of cable insulation
Insulation Resistance tests should be made in such a manner that safe operation of trains is not affected. While conducting the tests, it should be ensured that no unsafe conditions are set up by the application of test equipment. All conductors in signaling cables must be tested for their insulation in dry weather every year preferably during the same part of the year.
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Testing of cable insulation
The insulation Resistance Tests should be made when conductors, cables and insulated parts are clean and dry. In addition to regular testing of the cable in dry weather, random tests in wet weather may also be carried out where considered necessary. Spare cores may be tested for insulation once a year during monsoon periods to check.
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Testing of cable insulation
The conductors of the cables possess appreciable electrostatic capacity and may accumulate electrostatic charge. The cable conductors should be shorted or earthed to completely discharge any accumulated charge: (i) Before connecting the insulation tester while commencing the test and (ii) before the Insulation tester is disconnected when the test is completed. This is in the interest of safety of personnel and protection of equipment.
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A 500V insulation tester should be used for insulation testing. The insulation resistance should therefore be recorded after the test voltage has been applied for one minute or so when the indicator of the insulation meter shows a steady reading. Any metallic sheath or metal work of any rack or apparatus case should be bonded to earth during test.
Testing of cable insulation
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Procedure: Disconnect all cores of a cable at both ends. The disconnection may be made through links of ARA terminals if provided. Connect one terminal of the insulation tester to the conductor under test and other terminal to all the other conductors being bunched together and connected to earth.
Testing of cable insulation
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Procedure: Connect one terminal of the insulation tester to the conductor under test and other terminal to all the other conductors being bunched together and connected to earth. Similarly, test remaining conductors of the cable one by one Insulation resistance so measured should not be less than 20 mega ohms irrespective of the length of cables. In such cases where it is less than 20 mega ohms, the periodicity of testing should be increased to twice a year.
Testing of cable insulation
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Procedure If the insulation value is found to be less than 10 mega ohms, the cause should be investigated and immediate steps taken to repair or replace the cable to prevent any malfunctioning of the equipment and circuits. The conductors, which are showing below 05 mega ohms, should be identified and till the defects are rectified, these conductors shall not be used for any circuit. Such defective conductors shall be provided with distinctive markings at both the ends of termination for ease of identity during normal maintenance
Testing of cable insulation
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Earth leak indicators & Earth leak protectors. The use of these devices may also be considered for modern signalling installations such as Route Relay, Interlocking, Panel Interlocking & Centralised traffic Control systems.
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Proforma for Cable Testing
____________ Railway
Station ___________________
CABLE INSULATION RESISTANCE TEST SHEET
Main/Tail* Cable
1. Location: From . . . . . . . . . . . . . . . . To . . . . .. . . . . . .
. . . .
2. Cores: .
3. Size: .
4. Grade 250/440/650/110OV
5. Length:
6. Type: Unscreened/Screened
7. Insulation: PVC/Paper *
8. Date of installation/Commissioning . . . .
9. Name of the manufacturer: . . . . . . . . . . .
* Strike out whichever is not applicable.
- - - - - - -
- - - - - -
Core No. Date of Test
or Designation and whether
wet, damp or dry.
- - - - - - -
- - - - - -
Temperature:
Remarks:
Signature
These instructions are to be followed in addition to those contained in paras 614 to 618, 623 to 625, and
963/964 of the Signal Engineering Manual (Given in Annexure ‘A’)
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TESTING OF SIGNALLING CABLES
Various faults develop in cable are
a) Earth faults b) Open circuit fault and c) Contact fault Methods of testing generally the following methods are
used for testing of cables. a) Megger method b) Volt meter method c) Testing lamp method Among the above megger method prefers for signalling
cable testing meggering requires a) 500 V insulation tester. b) good earthing arrangement and c) communication arrangement. 8/21/2020 S19 Relays and cables 260
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Difference between Screened and Un Screened Cable
s.
no
Screened cable Unscreened cable
1 IRS specification S-35/93 IRS specification S-63/07 2 It is PVC insulated metal
sheathed armoured cable It is a PVC insulated armoured cable
3 Cable screening factor 0.4 No screeining factor 4 Manufacturing cost more Manufacturing cost less 5 No more use in future
Installation In future installation only to be used Unscreened cable
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CABLE SCREENING FACTOR
If any conductor lies in the magnetic field of the main source, it reduces the induced voltage of the S&T conductor. This property has been taken advantage of in the manufacturing of cables. While the cable cores are individually insulated and provided with insulated sheathing to make them compact, one more metallic sheathing is provided over this. The entire cores and metallic sheath are then covered by an insulated overall sheathing. This metallic sheathing can be in the form of an aluminium extruded pipes or strips of Aluminium covering the cores. These type of cables are called screened Cables.
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CABLE SCREENING FACTOR
In considering the screening effect of a cable sheath one must distinguish between the voltage of the core to the sheath and voltage of the core to the earth. If the metallic sheath is insulated from earth, identical voltages are induced in the sheath and core. The voltage between them is zero. At the same time, the metallic sheath does nothing to reduce the voltage between core and earth. It is, for this purpose, earthing of cables sheath at frequent intervals is insisted upon for providing an effective screening.
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CABLE SCREENING FACTOR
To reduce the voltage in the core, the sheath must have a current flow, the field of which opposes the field induced by the current in the catenary. For it to carry such a current, the cable sheath to be a part of a circuit that is completed through the earth. A.C sheath that insulates from earth or earthed at one place only, no screening effect on the Voltage between core and earth. The induced voltage in the core reduces considerably by using screened cables. The extent by which the induced voltage is reduced is called as "Screening Factor“.
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• Metal sheathed cables were used (with earthed sheaths) which provided screening effect due to induced currents in them.
Screening Factor = Voltage induced in a screened cable/ Voltage induced in an unscreened cable
typical value for a signaling cable – 0.4
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CABLE SCREENING FACTOR
Why un screened cable only used?
1. If screened cable is used cable screened factor should be 1 instead of 0.4.
2. Screened factor can’t be maintained in India.
3. To maintain screening factor 1, earth resistance required almost negligible ( less than 1 ohms ). So, it may not possible in India.
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