installation operation maintenance '1 … • operation • maintenance 1; ... is a...
TRANSCRIPT
�.1-l Ci /Y OC\ I.L. 41-334.1A
INSTALLATION • OPERATION • MAINTENANCE
1;\g/ ... '1 INSTRUCTIONS � * � /----------------------------------------------------------------------------------------------------------------------------------------------------
r--
TYPE CA-4 PERCENTAGE DIFFERENTIAL RELAY
CAUTION Before putting protective relays into
service, remove all blocking which may have been
inserted for the purpose of securing the parts dur
ing shipment, make sure that all moving parts oper
ate freely, inspect the contacts to see that they are
clean and close properly, and operate the relay to
check the settings and electrical connections.
APPLICATION
The type CA-4 percentage differential relay is
designed for the differential protection of three
winding transformers, and has three restraining
coils - one for each winding of the transformer. It is a current-operated induction disc relay designed
so that the operating coil current required to close
the contacts varies in proportion to the current
through the restraining windings. This feature pre
vents tripping on through faults, because of unbal
anced current transformer characteristics or loading,
and allows the relay to be set for sensitive protec
tion. The relay has three percentage taps of 15, 25
and 40%. The choice of a particular tap is based
on the performance of the main current transformers
under heavy through faults and the severity of the
magnetizing current inrush when the protected trans
former is energized.
When this magnetizing inrush current is large
enough in magnitude and long enough in duration to
cause the Type CA-4 relay to trip when the trans
former is energized, it is necessary to provide aux
iliary time-delay features to restrain the action of
the Type CA-4 until the magnetizing current has
diminished below the pick-up value of the relay.
The time-delay relay used for this purpose is the
Type TSI Magnetizing Inrush Tripping Suppressor
Relay described in I. L. 4 1-346. 1.
External current balancing auto transformers are
required where the main current transformers do not
provide equal secondary currents with the correct
phase relation for the Type CA-4 restraining wind-
SUPERSEDES I.L. 41-334.1 *Denotes change from superseded issue.
ings. Figures 8 and 9 show the auxiliary auto
transformers and Type CA-4 relay external connec
tions for typical installations.
The power transformer connections as shown in
Figs. 8 and 9 have been made on the assumption
that the delta winding is the low voltage side of the
transformer, and in conformance with the ASA Stand
ard that the voltages on the HV side lead the volt
ages on the LV side by 30"
· In following the relay
connections it will be simpler to illustrate the prin
ciples involved by using a two-winding transformer
application. The method illustrated may then be
applied to any transformer bank, whether in con
formance with the standard or not. When applied
to a three winding bank, each delta winding is
checked separately against the star winding.
F'ig. 6 shows a two winding transformer protected
by three differential relays. In order to establish
the proper connections to the relays, first assume a
set of reference currents, A, B and C flowing into
the wye side of the transformer. The currents
flowing out of the delta side of the transformer will
by A-C, B-A, and C-B, as shown in F'ig. 6, by virtue
of the way this particular bank is connected. On
the delta side of the power transformer the current
transformers will be connected in star. The con
nections to the relays must be such as to have the
same currents entering and leaving the relay through
the restraining windings, for the condition illustrated
of primary current flowing through the bank. Con
sidering the top relay, for example, it is seen that
A-C current delivered to the right hand restraining
coil from the a-phase current transformer on the
delta side of the bank is passed right on through the
other restraining coil of the relay to satisfy the re
quirements of the A- and c- phase current trans
formers on the wye side of the bank. This keeps
the current out of the operating coil, which is proper
for the through load condition illustrated by the
primary current direction arrows. An improper con
nection in the diagram will show up in this analysis
EFFECTIVE SEPTEMBER 1957 www . El
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TYPECA-4RELAY ____________________________________ ______________________ __
INDICATIIIG CONT.I.CTORSWITCH
IIOTE:
li�To3h�·J�P�RED H RElAY CASE
INTERNAL SCHEMATIC
182A'730
Fig. 1. Internal Schematic of the Type CA-4 Relay In the Type FT3l Case,
through involving the op0rating coil of one or more
relays in the return circuit for the currents, or
through not having the same current entering and
leaving the restraining coils for the same relay.
J:<'ig. 7 is similar to Fig. 6 except that the delta
connected windings are the high voltage windings,
necessitating a rearrangemel'l.t of connections to
satisfy the requirement that the high side voltages
lead the low side voltages by 30 •. This changes
the currents to the relays to A-B, B-C, and C-A
instead of the A-C, B-A, and C-B currents of Fig. 6.
CONSTRUCTION AND OPERATION
DIFFERENTIAL UNIT
The type CA-4 relay operates on the induction
disc principle and consists of four electromagnets
operating ·on two discs which are fastened to the
same shaft. Three of the electromagnets are re
straining elements and are connected to receive the
secondary currents from the various current trans
formers. The fourth electromagnet element is con
nected to receive the differential or unbalance cur
rent. The operating winding is tapped so that the
relay will just operate on 15, 25, or 40 percent un
balance. An extra connector block screw is pro·
vided so that taps on the relay can be changed with
out opening the current differential circuit.
The currents in the three restraining elements
produce contact opening torque proportional to the
currents in the various windings of the protected
2
transformer. The current in the difference or opera
ting element produces a contact closing torque pro
portional to the difference of the three restraining
currents when these currents are flowing through the
power transformer. The necessary quadrature flux
to produce torque is supplied by the upper pole coil
of the electromagnet. These coils are excited by
transformer windings on the main poles of the vari
electromagnets.
Because of the restraint which exists in the
relay during through faults when the current is
heavy, the current transformer characteristics need
not be accurately matched, since there is a restrain
ing torque on the relay disc that permits a certain
discrepancy of current transformer ratio character
istics without resulting in faulty tripping. This is
illustrated in figure 2 which shows typical operating
characteristics for a through fault. f!'igs. 3 and 4
show typical time current curves for the type CA-4
relay.
INDICATING CONT ACTOR SWITCH UNIT (ICS)
The d-e indicating contactor switch is a small
clapper type device. A magnetic armatur,�. to which
leaf-spring mounted contacts are attached, is at
tracted to the magnetic core upon energization of the
switch. When the switch closes, the moving contacts
bridge two stationary contacts, completing the trip
circuit. Also during this operation two fingers on
the armature deflect a spring located on the front of
the switch, which allows the operation indicator
target to drop. The target is reset from the outside
of the case by a push rod located at the bottom of
the cover.
The front spring, in addition to holding the tar
get, provides restraint for the armature and thus
controls the pickup value of the switch.
CHA RACTERISTICS
The type CA-4 relay has three percentage taps,
15%, 25% and 40% on the operating coil. These
values represent the percentage unbalance current
required to operate the relay on a through to external
fault as shown by Fig. 5.
Typical time curves are shown in l<'igs. 3 and 4.
TRIP CIRCUIT
The main contacts will safely close 30 amperes
at 250 volts d-e and the seal-in contacts of the indi
cating contactor switch will safely carry this current
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TYPE CA-4 RELAy -- ---------------------------�-1-_L_. _41_-3_3�4-.lA
:::! RELAY CoNTACTS (LOS£ /J!IEN t'tiRROVTS � 50 PLOTTED ARE ABOVE CURVE. ++++++++++-++++
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'-J
Curve 235381
0��--_.�----------.. �-w�������� 0 2 0 40 60 80 100 AMPERES ltJTAL SHORT C!RCt/IT CURRENT THROI/uH RELAY. THIS Is TH£ GREATER OF THE 70TAL /Nt:0/'1/NG OR TOTAL OUTGOING CIIRRE/VTS As MEASURED Br' llt£ CURI?E.IYT lRA!vSF0R(-J£R:::.
Fig. 2. Typical Operatln!i Characteristic lor an External Fault.
0 0 20 40 60 80 100 120 Curve 165270 AMPERES
Fig. 3. Typical Time-Current Curves with Current in One Restraint Coil.
/40
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TYPECA -4RELAY __________________________________________________________ __
.6 -ttl+ H
.5
Q. .4
� R: � "l .3 �
8 �
.2
+ 1' _ _;_
h H + r++�+n �-t-1+ 20 40 60 80 100 /20 /40
AMPERFS Curve 165271
Fig. 4. Typical Time-Current Curves of the Type CA-4 Relay· One Third of Operating Coil Current In Each Restraint Coil.
long enough to trip a circuit breaker.
The indicating contactor switch has two taps
that provide a pickup setting of 0.2 or 2 amperes.
To change taps requires connecting the lead located in front of the tap block to the desired setting by
means of a screw connection.
TRIP CIRCUIT CONSTANT
Indicating Contactor Switch (ICS)
0.2 ampere tap 6. 5 ohms d-e resistance
2.0 ampere tap 0.15 ohms d-e resistance
INSTALLATION
The relays should be mounted on switchboard
panels or their equivalent in a location free from
dirt, moisture, excessive vibration, and heat. Mount
the relay vertically by means of the four mounting
holes on the flange for semi-flush mounting or by
means of the rear mounting stud or studs for pro
jection mounting. Either a mounting stud or the
mounting screws may be utilized for grounding the
relay. The electrical connections may be made
directly to the terminals by means of screws for
steel panel mounting or to the terminal studs fur-
4
nished with the relay for thick panel mounting. The
terminal studs may be easily removed or inserted
by lecking two nuts on the stud and then turning the
proper nut with a wrench.
For detaHed FT case information refer to I.L.
41-076.
SETTINGS
U�FFERENTIAL UNIT
Select the desired percent slope tap - - 15, 25 or
40. The 25% slope tap is recommended for trans
formers with no load taps. Where the transformers
have tap changing under load mechanisms, the 40%
tap is recommended.
�DICATING CONTACTOR SWITCH (ICS)
No setting is required on the ICS unit except the
selection of the current tap - 0.2 or 2.0 amperes.
This selection is made by connecting the lead lo
cated in front of the tap block to the desired setting
by means of the connecting screw. Where the CA-4
.., relay energizes a 125 or 250 volt d-e Type WL relay
switch, or its equivalent, the 0.2 ampere tap is
recommended.
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\
TYPE CA-4 RELAY ___________________________________________________________ I_.L_._4 1_-3_3_4 . __ 1A
LAMP
} 120 YOLTS ----+-4-----i-- 60 CYCLES
-----------� } 125 �.D.C.
COMMECTIOMS FOR CHECKING SPRING TENSION ADJUSTMENT
CA-'1 RELAY (FRONT YIEW)
LAMP
} 120 YOLTS ----+---------+- 60 CYCLES
-----------......_ }12!> �.D.C.
CONNECTIONS FOR CHECKING THE OPERATING CHARACTERISTICS
l83Al33 Fig. 5. Diagram of Test Connections.
ADJUSTMENTS AND MAINTENANCE
The proper adjustments to insure correct opera
tion of this relay have been made at the i.•x:tory and
should not be disturbed after receipt by the customer.
If the adjustments have been changed, the relay
taken apart for repairs, or if it is desired to check
the adjustments at regular maintenance periods, the
instructions below should be followed.
The top bearing screw should have approximately
.002" clearance between it and the shaft. Adjust
the stationary contact so that 1/4 inch contact
separation is obtained when the moving contact is
held open against its stop.
The tension of the spiral spring should be ad
justed so that the contacts just close bet"oeen 3. 9 to 4.1 amperes 60 cycles gradually increasing cur
rent thru the operating coil on the 40% tap. On the
25% tap these values are 2.1 to 2.6 amperes and on
the 15% tap, 1. 2 to 1.4 amperes. This current should
be passed thru the operating coil only as shown in
the left half of figure 5.
The relay operating characteristics of figure 2
may be checked by connecting the relay as shown in
the right half of figure 5.
With 80 amperes through the operating coil and
one of the restraining coils, the relay should close
the contacts properly with little chattering. If it
does not, look for incorrect location of the disc in
the air gap.
INDICATING CONTACTOR SWITCH (ICS)
Close the main relay contacts and pass suffi
cient d-e current through the trip circuit to close
the contacts of the ICS. This value of current
should not be greater than the particular ICS tap
setting being used. The indicator target should
drop freely.
ENERGY REQUIREMENTS
The burden of the type CA-4 restraining wind
ings with 5 amperes flowing is . 75 volt-amperes
per element. lvith 5 amperes flowing through the
operating winding its burden is as follows:
15% Tap
25%
40%
24.0 volt amperes
8.5 " 3.3 II
58" Lag 53"
45°
II
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TYPE CA-4 RELAY
A _A_
TYPE CA RELAYSL_-
•-o LV �
�r ,---s l__
B-A � ,. C-B
"L
C_c_ --
_A-C
---------
�
_c-e Jrn_ _ �--___ _
�" I_
b
Fig. 6. Current and Voltage Relatioaships for Wye- Delta Transf-:rmer Differential Protection - WYe Volt· ages Lead Delta Voltages by 30",
87 5 87 T
TRANS FORMER BANK
IL IC
fi� EF-=-
a b c
=c lr _A-B c ---=:.- j -n-----L+--- --"�� --- . I
TYPE C4 �ELA.Y$-1 --- . , B-C ' B-C I I --.. -- - ,�--�-��J-t--
------ -- �--J =
Fig. 7. Current and Voltage Relationships for Wye - Delta Transformer Differential Protection D.,lta Voltages Lead Wye Voltages by 30".
p��- __ ,.:..;.;..;.;;;;;_=NEil.
u Lti-, I
I
--� p �CURRENT BALANCE AUTO TRANSFORMERS
87 T +
��ICS 1 � �w86
PH. 1
NEG. OR -----------------
POS.
DEi ICE MUMaER CHART 87 - PERCENTAGE DIF FEREMTIAL RELAY
TYPE CA-<
87R - RESTRAINIMu COIL OF THE TYPE C A-q RELAY
870P - OPERATING COl L OF THE TYPE
CA-q RELAY
ICS - IHOICATIHu CONTACTOR SWITCH 86- AUXILIARY TRIPPING RELAY
PM. l TYPE WL
PM. J
288B�8o Fig. 8. External Schematic of the Type CA-4 Relay for Wye - Delta -Delta Transform er Protection.
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TYPE CA-4 RELAY ----------------------------___:•:::·L::.·.:;_4.:_1·:::.:33:::4.:.:.1-=...A
TIIANSFOKMER BANK
B A
POS. D.C. TRIP BUS OR --.-------
'----- CURRENT BAL AHCE AUTO TRANSFORMER
NEG.
NEG. OR
POS.
DEVICE NUMBER CHARTS
87 • PERCENTAGE DIFFERENTIA� REUY TYPE CA-�
87R • RESTRA I M I NG CO I� OF THE TYPE CA-� RE�AY
870P • OPERATINii COl� OF THE TYPE CA-� RE�AY
ICS - INDICATING CONTACTOR SWITCH
86 - AUXILIARY TRIPPINil RELAY TYPE WL
288B581 Fig. 9. External Schematic of the Type CA-4 Relay for Wye - Delta - Wye Transformer Protect/on.
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TYPE C�4 RELAY ________________________________________________________ __
190·32 SCRE.W
SPACER FOR TH\t-.1 P"NE.LS
.5 -I Q ':.CREW IG (F"OR \\-\IC� �\JEL IJSE � -16 ':>IUD) \10
,I90-3Z. SCREW (FOR \HICK. """"W'EL use:
. 1 9 0 -32. 5\UD)
T�RMINAL ANt> MOUNTIN<I DE1AIL'O
_!__ DIA. 4-1-\0LES f"OR 4.190-32. MTG. 'OCR£W�
PANEL CUTCllT $ DRILLIWGr FOR. SEMI-FLUC:.H MT�.
I \3z.
PA.NEL CRILL\� OR. CUTOUT 'PROJ&:C.T\ON MTGr.
( FRO\.tT \J\EW)
3 -eR.
TERMINAL NUMeER.
57-D-7902
Fig. JO. Outline ana Drilling Plan for the Type CA-4 Relay In the FT31 Case.
WESTINGHOUSE ELECTRIC CORPORATION METER DIVISION • N,EWARK, N.J.
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t(G I.L. 41-334. 1A �0 INSTALLATION • OPERATION • MAINTENANCE
���El-J_I_ N_S_T_R_U_C_T_I _O_N_S_ .. * ..
,.....-
TYPE CA-4 PERCENTAGE DIFFERENTIAL RELAY
CAUTION Before putting protective relays into
service, remove all blocking which may have been
inserted for the purpose of securing the parts dur
ing shipment, make sure that all moving parts oper
ate freely, inspect the contacts to see that they are
clean and close properly, and operate the relay to
check the settings and electrical connections.
APPLICATION
The type CA-4 percentage differential relay is
designed for the differential protection of three
winding transformers, and has three restraining
coils - one for each winding of the transformer. It is a current-operated induction disc relay designed
so that the operating coil current required to close
the contacts varies in proportion to the current
through the restraining windings. This feature pre
vents tripping on through faults, because of unbal
anced current transformer characteristics or loading,
and allows the relay to be set for sensitive protec
tion. The relay has three percentage taps of 15, 25
and 40%. The choice of a particular tap is based
on the performance of the main current transformers
under heavy through faults and the severity of the
magnetizing ct.UTent inrush when the protected trans
former is energized.
When this magnetizing inrush current is large
enough in magnitude and long enough in duration to
cause the Type CA-4 relay to trip when the trans
former is energized, it is necessary to provide aux
iliary time-delay features to restrain the action of
the Type CA-4 until the magnetizing current has
diminished below the pick-up value of the relay.
The time-delay relay used for this purpose is the
Type TSI Magnetizing Inrush Tripping Suppressor
Relay described in I. L. 41-346.1.
External current balancing auto transformers are
required where the main current transformers do not
provide equal secondary currents with the correct
phase relation for the Type CA-4 restraining wind-
SUPERSEDES I.L. 41-334.1 *Denotes change from superseded issue.
ings. Figures 8 and 9 show the auxiliary auto
transformers and Type CA-4 relay external connec
tions for typical installations.
The power transformer connections as shown in
Figs. 8 and 9 have been made on the assumption
that the delta winding is the low voltage side of the
transformer, and in conformance with the ASA Stand
ard that the voltages on the HV side lead the volt
ages on the LV side by 30"
· In following the relay
connections it will be simpler to illustrate the prin
ciples involved by using a two-winding transformer
application. The method illustrated may then be
applied to any transformer bank, whether in con
formance with the standard or not. When applied
to a three winding bank, each delta winding is
checked separately against the star winding.
Fig. 6 shows a two winding transformer protected
by three differential relays. In order to establish
the proper connections to tbe relays, first assume a
set of reference currents, A, B and C flowing into
the wye side of the transformer. The currents
flowing out of the delta side of the transformer will
by A-C, B-A, and C-B, as shown in Fig. 6, by virtue
of the way this particular bank is connected. On
the delta side of the power transformer the ctnTent
transformers will be connected in star. The con
nections to the relays must be such as to have the
same currents entering and leaving the relay through
the restraining windings, for the condition illustrated
of primary current flowing through the bank. Con
sidering the top relay, for example, it is seen that
A-C current delivered to the right hand restraining
coil from the a-phase current transformer on the
delta side of the bank is passed right on through the
other restraining coil of the relay to satisfy the re
quirements of the A- and c- phase current trans
formers on the wye side of the bank. This keeps
the current out of the operating coil, which is proper
for the through load condition illustrated by the
primary current direction arrows. An improper con
nection in the diagram will show up in this analysis
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TYPE CA-4 RELAY ________________________________________________________ __
IIIT£RMAL SCHEMATIC
MOTE:
!�To3l:·��P�REO FRONT VIEW ATIElAYCASE
BOTTOM FRONT (F.V.)
BOTTOMREAR(F.Y.)
CHASSIS OPERATED --1----t---r-SIIORTING SWITCH
REDIIAIIDLE TEST SWITCH CURRENT TEST .JACK
TEII�INAL
182A730
Fig. J. Internal Schematic of the Type C A-4 Relay In the Type FT31 Case.
through involving the operating coil of one or more
relays in the return circuit for the currents, or
through not having the same current entering and
leaving the restraining coils for the same relay.
l<,ig. 7 is similar to Fig. 6 except that the delta
connected windings are the high voltage windings,
necessitating a rearrangemel'lt of connections to
satisfy the requirement that the high side voltages
lead the low side voltages by 30°
. This changes
the currents to the relays to A-B, B-C, and C-A
instead of the A-C, B-A, and C-B currents of Fig. 6.
CONST RUCTION AND OPERATION
DIFFERENTIAL UNIT
The type CA-4 relay operates on the induction
disc principle and consists of four electromagnets
operating · on two discs which are fastened to the
same shaft. Three of the electromagnets are re
straining elements and are connected to receive the
secondary currents from the various current trans
formers. The fourth electromagnet element is con
nected to receive the differential or unbalance cur
rent. The operating winding is tapped so that the
relay will just operate on 15, 25, or 40 percent un
balance. An extra connector block screw is pro
vided so that taps on the relay can be changed with
out opening the current differential circuit.
The currents in the three restraining elements
produce contact opening torque proportional to the
currents in the various windings of the protected
2
transformer. The current in the difference or opera
ting element produces a contact closing torque pro
portional to the difference of the three restraining
currents when these currents are flowing through the
power transformer. The necessary quadrature flux
to produce torque is supplied by the upper pole coil
of the electromagnet. These coils are excited by
transformer windings on the main poles of the vari
electromagnets.
Because of the restraint which exists in the
relay during through faults when the current is
heavy, the current transformer characteristics need
not be accurately matched, since there is a restrain
ing torque on the relay disc that permits a certain
discrepancy of current transformer ratio character
istics without resulting in faulty tripping. This is
illustrated in figure 2 which shows typical operating
characteristics for a through fault. F'igs. 3 and 4
show typical time current curves for the type CA-4
relay.
INDICATING CONTACTOR SWITCH UNIT (ICS)
The d-e indicating contactor switch is a small
clapper type device. A magnetic armature, to which
leaf-spring mounted contacts are attached, is at
tracted to the magnetic core upon energization of the
switch. When the switch closes, the moving contacts
bridge two stationary contacts, completing the trip
circuit. Also during this operation two fingers on
the armature deflect a spring located on the front of
the switch, which allows the operation indicator
target to drop. The target is reset from the outside
of the case by a push rod located at the bottom of the cover.
The front spring, in addition to holding the tar
get, provides restraint for the armature and thus
controls the pickup value of tbe switch.
CHA RACTERISTICS
The type CA-4 relay has three percentage taps,
15%, 25% and 40% on the operating coil. These
values represent the percentage unbalance current
required to operate the relay on a through to external
fault as shown by Fig. 5.
Typical time curves are shown in l<,igs. 3 and 4.
TRIP CIRCUIT
The main contacts will safely close 30 amperes
at 250 volts d-e and the seal-in contacts of the indi
cating contactor switch will safely carry this current
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TYPE CA-4 RELAY _________________________________________________________________________________________________________ I . L_._ 4_1-_33_4_.1_A
::;! lij RELAY CONTACTS (LOSE �£/HEN t'tJRR£NTS ,a 50 ��� PLOTTEO ARc ABOVE CURVE. : rr TT HTl+-LI::uuW-ll I I WI r I� -III-I I �H.I-W U++-� � [�· . DASH LINE 3 RESTJf'AIN/N(j Ei.£MENTS CNERGIZED .::: c-;SOLIO LIN£- 2 RESTHAININ(j ELEMENTS ENEIUiiZEO � 4o 1
+ r-F ' H-� . . . . � tt 1; •l -.
<;:::) �- t ::):. � f � 30 � I
1
Curve 235381
Fig. 2. Typical Operating Characteristic lor an External Fault •
. 5 C'ONTACT 7/i>A VEL t
.I
0 0 20 Curve 165270
40 60 80 AMPERES
100 120
Fig. 3. Typical Time-Current Curves with Current In One Restraint Coli.
140
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TYPE CA-4RELAY ____________________________________________________ __ __
.6
.5
It .4
Ci: I' � "' .3 � 8 �
.2
.I
r
+- H-' ' 2S% TAP -" ll_] ' IS" "l'o TAP
+-+-+-<++-+-++ 1H T •++++ + , 1 , , T Jti J4 ltvcH CotvTA,cT TRAVEL ' W--1---1----l-+---1+-it '
+-H-'-=1 i -
T t
+
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+�
' -+--'
i
' H- -
' '
-i-+ t-l-H
'
0 4() 60 80 /00 120 /40 AMPERES Curve 165271
Fig. 4. Typical Time-Current Curv .. of the Type CA-4 Relay. One Third ol Operating Coil Current In Each Restraint Col/.
long enough to trip a circuit breaker.
The indicating contactor switch has two taps
that provide a pickup setting of 0.2 or 2 amperes.
To change taps requires connecting the lead located
in front of the tap block to the desired setting by
means of a screw connection.
TRIP CIRCUIT CONSTANT
Indicating Contactor Switch (ICS)
0.2 ampere tap 6.5 ohms d-e resistance
2.0 ampere tap 0.15 ohms d-e resistance
INSTALLATION
The relays should be mounted on switchboard
panels or their equivalent in a location free from
dirt, moisture, excessive vibration, and heat. Mount
the relay vertically by means of the four mounting
holes on the flange for semi-flush mounting or by
means of the rear mounting stud or studs for pro
jection mounting. Either a mounting stud or the
mounting screws may be utilized for grounding the
relay. The electrical connections may be made
directly to the terminals by means of screws for
steel panel mounting or to the terminal studs fur-
4
nished with the relay for thick panel mounting. The
terminal studs may be easily removed or inserted
by lecking two nuts on the stud and then turning the
proper nut with a wrench.
For detaHed FT case information refer to I.L.
41-076.
SETTINIGS
DIFFERENTIAL UNIT
Select the desired percent slope tap -- 15, 25 or
40. The 25% slope tap is recommended for trans
formers with no load taps. Where the transformers
have tap changing under load mechanisms, the 40%
tap is recommended.
llroiCATING CONTACTOR SWITCH (ICS)
No setting is required on the ICS unit except the
selection of the current tap - 0.2 or 2.0 amperes.
This selection is made by connecting the lead lo
cated in front of the tap block to the desired setting
by means of the connecting screw. Where the CA-4
... relay energizes a 125 or 250 volt d-e Type WL relay
switch, or its equivalent, the 0.2 ampere tap is
recommended.
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TYPE CA-4RELAY _________________________________________________ ___________ I
._L_.4_1_-3_u_. __ 1A
CA•" RELAY (FRONT VIEW)
11 = TOTAL RESTRAINING COIL CURRENT
10 = OPERATING COIL CURRENT
LAICP
} 120 VOLTS ----+-.... -----� 60 CYCLES
-----------� } 125 �.o.c.
CO .. ECTIOIS FOR CHECKING SPRING TEISIOM AD�USTMENT
LAICP
} 120 VOLTS ----+---,._ ___ _,_ 60 CYCLES
___________ _..._} 125 v.o.c.
CONNECTIONS FOR CHECKING THE OPERATING CHARACTERISTIC�
183Al33
Fig. 5. Diagram ol Test Connections.
ADJUSTMENTS AND MAINTENANCE
The proper adjustments to insure correct opera
tion of this relay have been made at the factory and
should not be disturbed after receipt by the customer.
If the adjustments have been changed, the relay
taken apart for repairs, or if it is desired to check
the adjustments at regular maintenance periods, the
instructions below should be followed.
DIFFERENTIAL UNIT
The top bearing screw should have approximately
.002" clearance between it and the shaft. Adjust
the stationary contact so that 1) 4 inch contact
separation is obtained when the moving contact is
held open against its stop.
The tension of the spiral spring should be ad
justed so that the contacts just close between 3. 9
to 4.1 amperes 60 cycles gradually increasing cur
rent thru the operating coil on the 40% tap. On the
25% tap these values are 2.1 to 2.6 amperes and on
the 15% tap, 1.2 to 1.4 amperes. This current should be passed thru the operating coil only as shown in
the left half of figure 5.
The relay operating characteristics of figure 2
may be checked by connecting the relay as shown in
the right half of figure 5.
With 80 amperes through the operating coil and
one of the restraining coils, the relay should close
the contacts properly with little chattering. If it
does not, look for incorrect location of the disc in
the air gap.
INDICATING CONTACTOR SWITCH (ICS)
Close the main relay contacts and pass suffi
cient d-e current through the trip circuit to close
the contacts of the ICS. This value of current
should not be greater than the particular ICS tap
setting being used. The indicator target should
drop freely.
ENERGY REQUIREMENTS
The burden of the type CA-4 restraining wind
ings with 5 amperes flowing is . 75 volt-amperes
per element. With 5 amperes flowing through the
operating winding its burden is as follows:
15% Tap 25%
40%
24. 0 volt amperes 8.5 II II
3. 3 II
58" Lag
53°
45°
II
"
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TYPE CA-4 RELAY
TYPE CA RELAYS �--f----��
Fig. 6. Current and Voltage Relationships for Wye -Delta Transformer Dllferentlol Protection- WYe Volt· ages Lead Delta Voltages by 30".
TRAMSFGaMER BANK
� ;::r l)s IL � � 41---
3e IL
� L,O. ��� c
t�t �� � � � rP B. B � c 8 A 8�1 jZ 87 v+ 87�- 1 87 s * 87 v+ 87;t-I � � .r+ 87��
·v � d�( 87 3
¥ ,,-. 87�-2 87 ¥ v+ 8;{-2 � ¥_ ,,-. B;�v_l �
v � �-J � 87 �87RA J d7 5 � v •I+87;�
llj lv- � .r+87R·J �
• � LV HV
,---3 • L _1j �:• � ;J l
.1§ t!s c c � s J i§ ��c
_A-8 �h I TYPE CA RELAYS�
�
�� ��
a b c A-tl
�
��
�
;::;:::;..... � B-C I_
�' � C-A
L_ rYY--.. � L_
v�r �b 'bt)
Vc Vba
Fig. 7. Current and Voltage Relationships for Wye -Delta Transformer DIHerential Protection Delta Voltages Lead Wye Voltages by 30".
� ,---J ,_,
rv--. u
u
I ��
Lt.-,. �
1 87 2
"--.cuRRENT BAL AHCE RMERS AUTO TRANSFO
} '"·
' 8 87
1 '" '
I
P•·
J
NEG.
OR __ .,._. _____ _ POS.
DEVICE NUM8ER CHART 87 - PERCENTAGE DIFFERENTIAL RELAY
TYPE CA-'1 7R • RE STRAINING COIL OF THE TYPE
CA-'1 RELAY
OP - OPERATING COl L OF THE TYPE
CA-'1 RELAY
CS - INDICATING COHTACTOR SWITCH 86 - AUXILIARY TIIIPPI N G RELAY
TY P E WL
288B'S80 Fig. 8. External Schematic of the Type CA-4 Relay for Wye -Delta -Delta Transformer Protection.
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TYPE CA-4RELAY _______________________________________________________ �J�.L�.4�1���34�·�1A
87 5 87
(
87 5
TUII$FOIIMER BANK POS. D.C. TRIP BU$
OR ----��----------NEG.
87 2
'\__ CURRENT BALANCE AUTO TRANSFORMER
} �. 3
NEG. OR ---41-----------..
POS.
DEVICE NUMBER CHART$
87 • PERCENTAGE DIFFERENTIAL RELAY TYPE CA-�
87R • RESTRAIIIING COIL OF THE TYPE CA·� RELAY
870P • OPERATING COl L OF THE TYPE CA·� RELAY
ICS • INDICATING CONTACTOR SWITCH
86 • AUXILIARY TRIPPING RELAY TYPE WL
288B581
Fig. 9. External Schematic of the Type CA-4 Relay for Wye -Delta - Wye Transformer Protection.
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TYPEC�4RELAY--------------------------------------------------------
190·32. SCRE.W
SPACER FOR 1\-\IN P/\N·L�
_s -I Q SCREW II<> (FOR \�IC�
R'..\JE\... IJSE ..:i-IS '!)TUD) IE>
,I90-3Z. SCREW (FOR. \HICK. l"'�N'E\... US.E.
. 1 9 0 -.32. '5\UO)
T�RMINAL AWO MCUNTII'lCJ DEtAIL�
� DIA.. 4�0LES FOR .190-32. MTG. <;;,CREWS
PANEL C.UTO\lT t DRILLINGFoR 'SEM\-FLUC:.H MTQ-.
I I '5""t. '�
PANEL CRILL\� OR C.\JTO\JT f>ROJi:CT\ ON M'T'Or.
( FR�T \1\EW) 5'7-D-'7902
Fig. JO. Outline anJ Drilling Plan for the Type CA-4 Relay In the FTJJ Case.
WESTIN GHOUSE METER DIVISION
ELECTRIC •
CORPORATION NEWARK, N.J.
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