INDEX

1. ABSTRACT2. PROFILE OS VISAKHAPATNAM STEEL PLANT3. INTRODUCTION TO COMMUNICATION SYSTEMS IN VSP4. PRINCIPLES OF TDM- PCM5. THE 3000 LINES TOWNSHIP TELEPHONE EXCHANGE6. ADVANTAGES WITH MODERN ELECTRONIC EXCHANGES7. CONCLUSION

1. ABSTRACT

The title of the project is “WORKING OF SIEMENS HIPATH-4000

LINES ELECTRONIC EXCHANGE”the project aims at studying the various units employed in the electronic exchange right from construction phase to implementation and operation phase.

The project is undertaken at the Visakhapatnam steel plant. The town ship electronic exchange is installed by MIS SIEMENS INDIA LIMITED and has been built with SIEMENS Technology of GERMANY. This HIPATH 4000-model exchange is designed initially for 3000 subscribers and is capable of extending beyond 5760 ports at a later stage.

The report mainly covers the basic principles of Electronic Exchanges and about 3000 lines VSP-Township exchange its working principle, different components and its advantages.

Basically this exchange is an ISDN exchange, which means ‘Integrated Services Digital Network” exchange. That means this exchange supports voice signals as well as data and video signals. There by the capabilities of the exchange is an enhanced compared to older type electronic exchange.

This exchange is a micro processor based one, which employs “PENTIUM” Processor for its call-processing and switching functions.

2. PROFILE OF VISHAKAPATNAM STEEL PLANT

ABOUT THE ORGANIZATION

Vishakhapatnam Steel Plant the first coastal based steel plant of India is located 16

km’s south west of city of destiny. Bestowed modem technologies VSP has an installed

capacity of 3 million tons per annum of liquid steel 2.66 million tons of salable steel. At VSP,

there is emphasis on total automation seamless integration and efficient up gradation, which

results in wide range of long and structural products. To meet stringent demands of disceming

customers with in India and abroad. VSP products meet exalting international quality standards

such as JIS,DTN,BIS and BS etc.

VSP has the distinct to be first integrated steel plant in India to become a ISO-9002

certified company. The certificate covers quality systems of operational, maintenance, and

service units besides purchase systems, training and marketing functions spreading over four

regions regional marketing offices ,20 branch offices and 22 stock yards located all over the

country.

VSP by successfully installing and operating efficiently Rs 460 cores worth of pollution

Control and environment control equipments and converting the barren landscape by planting

more than thee million plants has made the steel plant township, and surrounding areas in to a

Heaven of lush greenery. This has made steel township a greener, cleaner and cooler place

which can boost 3 to 4 degrees centigthde lesser temperature even in peak summer compared

to Visakhapatnam city.

The entire steel plant is divided into various zones such as,

COKE OVENS:

These tall ovens takes raw coal as input and produces coke by processing the coal in the

absence of air or oxygen. This shop manufactures and supplies coke, a hard porous solid fuel

for blast furnaces.

BLAST FURNACES:

Tall and vertical furnaces, which provide hot metal at high pressure and temperature.The

output of this furnace is liquid iron and can be casted directly into pig shaped mould called pig

iron or can be sent to Steel Melt Shop for further steel making process

STEEL MELT SHOP:

A place where the quality of steel is improved by heating and oxygen lancing

process.The output of this plant is called Liquid steel which is further sent to mills area for

shaping in different formats .

ROLLING MILLS:

A sophisticated, high capacity, high speed, fully automated mills, which gave final

shape to the steel products. The success of Visakhapatnam steel plant is attributed mainly to its

proper management of communication. Communication plays a vital role in coordinating the

activities of various departments in achieving the assigned targets and accomplishing the

desired performance.

The telecommunications department in VSP is catering for the communication needs of

the steel plant and township area for the past 22 years. In steel plant, very wide range of

communication systems is provided for meeting the day-to-day internal and external

communication needs.

3. INTRODUCTION TO COMMUNICATION SYSTEMS

3.1 INTRODUCTION:

The term communication system refers to the sending, receiving and processing of information by electronic means. As such, it started with wire telegraphy in 1840’s developing with the telephony some decades latter and radio at the beginning of the twentieth century. Radio communication made possible by the invention of the triode tube, which became more widely used and refined through the invention of transistor, integrated circuit and the semiconductor devices. More recently the use of satellites and fiber optics has made communication system more wide spread with an increasing emphasis on computer and other data communication.

A modem communication system is first concerned with the sorting, processing and storing of information before its transmission. The actual transmission then follows with further processing and filtering of noise. Finally we have reception, which may include processing steps as decoding, storage and interpretation. The various forms of communication at present includes radio telephony, telegraphy, broadcasting point to point and mobile communications, computer communications, radio telemetry, radar and radio aids to navigation.

The invention of telephone in 1876 has marked revolution in world’s telecommunication system. Soon it developed such that today, telephone network is far-flung highly complex and highly integrated ‘system extending into almost every nook and corner of all industrialized countries.

In earlier stages telephone switching was done manually. Modem switching is effected automatically as on the Strowger, Crossbar and electronic system of interconnection. These systems operate on the principle of common control with incoming pulses temporarily stored in the device, which then controls the switches directly or indirectly. In the recent past telephone dialing is done with out the aid of operators. In this system switching mechanism selects the route to distant telephone and if it finds the direct circuit busy, it explores in succession a number of alternate route and establishes the connection over the least circuitous path.

Further progress in the transmission is in the direction of digital rather than analog techniques. Speech signals will be multiplexed by the pulse methods with channels interleaved in time instead of frequency. The most promising method is pcm, which provides at the expense of bandwidth low vulnerability to interface and makes it possible to regenerate pulses perfectly at each repeater, so that there is no accumulator distortion and hence no noise and cross talk.

In contrast to electro-mechanical switching system, electronic system will afford a high degree of versatility through the program stored in the memory. Before long facilities will be available to have features such as simplified codes for reaching frequency called telephones subsequent

automatic completion of calls to a busy specified telephone, automatic centralized answering and like type.

More recently, communication satellite, employing microwave techniques are increasingly used to handle several thousand voice channels with the advent of the devices like traveling wave tube, the maser, the laser and the parametric amplifier optical communication system are coming into vogue.

Electronic computers have been increasingly used to telecommunication links for processing data collection, transmission and retrieval in private homes and in public utility services. Indeed the future holds prospects of further advances in communication techniques and acquires well to promote understanding and good will among men in different parts of the world.

Two major changes in telecommunication technology, which have significantly influenced the

telecom infrastructure, are the introduction of Digital Signal Processing in both switching,

multiplexing and transmission of signals through fiber optic network. The hardware technology

used in switching transmission and thermal equipment has undergone many changes since

1950 in India. In the switching area it has changed from Strowger to Cross - Bar in 1960, to

analog electronics in 1970s, to hybrid of digital and analog in 19 80’s and now to digital

electronics with higher level of emphasis on software based control in recent design. Similarly

transmission media on trunk routes has changed from electrical to optical. The growing

popularity of wireless transmission has resulted in a major impact on the terminal equipment

sector.

3.2 Overview Of Communication Systems in VSP:

In Visakhapatnam steel plant very wide range of communication systems are provided

for meeting the day-to-day internal and external communication needs.

These communication needs are broadly classified as follows:

General-purpose communication systems.

Process communication systems

Monitoring and signaling systems.

3.2.1. General Purpose Communication Systems:

The following facilities are provided under category of communication and signaling systems.

4000 lines electronic exchange plant.

3000 lines electronic exchange in township.

128 lines electronic exchange in township (UKKU HOUSE).

3.2.2 Process Communication System:

To facilitate coordinated operation and management of various production shops,

maintenance and service departments, the following process communication facilitate are

provided.

Dispatcher communication system.

Loudspeaker intercom system.

Loudspeaker conference system.

Industrial public address system.

Hot line communication system.

V.H.F. communication system.

3.2.2.1 Dispatcher Communication system:

Dispatcher communication systems are provided in raw material handling plant, coke

and coke chemicals departments steel melt shop, blast furnace, sinter plant, power distribution

and thermal power plant.

These are cordless switchboard type manual exchanges of electromechanical version

meant for catering to the intrashop process communication needs. Since manufacture of such

systems and their spares is discontinued in the country, these dispatchers are being placed by

electronic exchanges progressively. The dispatchers in plant control (H.O.D’s board), traffic

and medium merchant structural mill are already replaced by electronic exchanges. Everyday

teleconference is being conducted by E.D. (works) with all H.O.D.’s in the morning with the

help of digital EXCOM system provided in the plant control.

3.2.2.2 Loud Speaker Intercom System:

Loudspeaker Intercom Systems are provided in C&CC.D., B.F., S.P., L.M.M.M.,

W.R.M. and M.M.S.M. to facilitate intercommunication between various sections of individual

plant units on selective basis. Since the communication is carried out by means of microphones

and loudspeakers provided in the subscriber stations, this system is very useful in noisy

environment where conventional telephones prove to be ineffective. With this system it is

possible to establish communication between any two stations having interconnectivity on

selection basis. By using group call facility it is possible to communicate to more than one

location in a group simultaneously.

3.2.2.3 Loud Speaker broadcasting system:

Loud Speaker Broadcasting System is located in operation / maintenance personal

working on the shop floor as well as passing on important process instructions to all locations

in the shop area from the concerned control rooms. The system consists of centralized

amplifier rack with amplifiers, desktop gooseneck microphone with push to talk switch, zone

selector and a network of loud speakers connected to the amplifiers. These systems are very

useful for searching individuals on the shop floor and communicating with them.

3.2.2.4 Loud Speaker Conference System:

These systems are provided in C&C.C.D. to facilitate two-way communications

between various sections of the shop. Since the communication is carried out by means of

microphones and loudspeakers provided in the subscriber stations, this system is very useful in

noisy environment where conventional telephones prove to be Ineffective. The subscriber

stations are connected in a group and it is possible to have communication with any of the two

stations in that group. The ongoing conversation will also be heard by others connected in a

group.

3.2.2.5 Industrial Public Address System:

Industrial Public Address System in T.P.P. is a combination of loud speaker

broadcasting and conference communication system. From the main control room it is possible

to make announcements, which are heard at the shop floor. From certain locations the

communication can also be established through handsets in private mode with the main control

room.

3.2.2.6 Hot Line Communication System:

To ensure direct telephone communication between closely related critical locations,

direct communication systems are provided. In this system, specified locations are connected

permanently so that whenever one subscriber lifts his telephone the other will immediately get

a ring and communication can be achieved without any loss of time.

3.2.2.7 V.H.F. Communication System:

V.H.F. Communication systems are provided for establishing two-way communication

between operators inside the cabins of mobile technological equipments and mobile operation /

maintenance personal with their control rooms. These sets play very important role in

C&C.C.D. for proper coordination of the movement’s of the pusher cars, charging cars and dry

quenching operation coke oven batteries and C.D.C.P, areas. Hand held V.H.F. sets are

extensively used for establishing instantaneous communications among the mobile

operation/maintenance personal with their concerned control rooms. The sets ensure

instantaneous communication and effective coordination of operating / maintenance activities

in the plant.

3.2.3 Monitoring And Signaling Systems:

For monitoring critical operations in different production units continuously from the

concerned control pulpits, closed circuit television systems are provided by B.F., S.P., S.M.S.,

L.M.M.M., W.R.M. and M.M.S.M. departments. For ensuring fire safety in the plant and to

inform the central fire system immediately in case of any fire, a central fife alarm signaling

system is provided. In addition to these VSP exports quality pig iron & steel products to Sri

Lanka, Myanmar, Nepal, Middle East, USA, South East Asia. The Visakhapatnam Steel Plant

was awarded “Star Trading House “status during the period 1997-2000. Having established a

fairly dependable export market, VSP plans to make a continuous presence in the export

market. It has also won the “National Safety” award for the year 2003 for having followed the

best safety rules.

Having a total manpower of about 18,000 VSP has envisaged a labour productivity of

not less than 230 tones of liquid steel per man every year, which is the best in the country and

comparable with the International standards.

3.2.3.1 Closed Circuit Television Systems (CCTV):

Closed Circuit Television systems ensure supervision of critical operating areas of

major production units from their concerned control pulpits, Each of the C.C.T.V. Systems

essentially comprise television cameras, television monitor and control console interconnected

by means of control cables and video coaxial cables. Depending upon the requirements at the

site the system may consists of one camera and one monitor, or single camera and two

monitors, or four cameras and single monitor. In case of high temperature locations the

cameras are enclosed in water-cooling and air purging arrangements. For improving the

effectiveness of cooling, vortex coolers are provided in case of furnace cameras in L.M.M.M.,

W.R.M. and M.M.S.M. The cameras in B.F. are provided with remote control pan and tilt units

and remote controlled zoom lenses for close monitoring of the cast house operations from the

control rooms. The C.C.T.V. system is provided with technical features confirming to

C.C.LR.-B standards. The C.C.T.V. systems are provided at various plant units for observing

critical operations.

3.2.3.2 Central Fire Alarm Systems:

This is provided for communicating the exact location of outbreak of fire in any part of

the steel .plant complex to the central fire station and simultaneous actuation of sirens to alert

personal of the affected plant zone.

Communication to plant fire brigade station for exact location of fire in any part of the

plant is established either manually breaking the front glass cover of manual fire alarm boxes

which are provided at strategic locations of various plant units all over hypertension plant and /

or automatically through voltage free contacts of plant automatic fire detection and protection

system. On receipt of alarm through alarm line, the corresponding signal, will start automatic

flashing on hypertension corresponding signal lamp and shall start automatic flashing on the

mimic panel provided in the fire brigade system indicating the location of fire with

simultaneous actuation of audible alarm in the fire brigade station control room and appliance

room as well as hooting of sirens for a present time interval in the affected alarm zone to the

repeater alarm panel provided at fire fighting and drinking water house to alert attending

personal to start fire fighting pumps immediately.

For sake of simplicity and easy identification of the fire brigade station, the plant is

divided into a number of alarm zones. To restrict the number of alarm lines from each alarm

zone, a number of manual fire alarm boxes as well as voltage free contacts of automatic fire

detection and protection systems of shops and buildings of the concerned zones are connected

in series / parallel.

3.2.3.3 Shift Change Announcement System:

The shift change announcement siren system is provided for ensuring uniform accurate

shift timing through the plant. This system consists of two numbers of quartz crystal controlled

master clocks in the energy and telecom center. The shift timings are programmed in the

master clock. At this specific time, the signal will be transmitted for energizing the sirens

located at strategic points in plant area simultaneously at the present timings.

3.4 BASIC TELEPHONE SYSTEM

3.4.0. INTRODUCTION:

The basic telephone circuit is architecture around three ICs chipset consisting of dialing

block- realized by using IC UM9124B, ringer block-realized through IC KA 2418 and speech

block-realized through IC TEA 1062A.

The telephone circuit consists of the following functional blocks:

Ringer circuit.

Current limiter circuit.

Dialer circuit.

Speech circuit.

Protection circuit and

Special features.

3.4.1 RINGER CIRCUIT:

external resistor R42 (1 5 K) and capacitor C42 (O.OluF) volume of ringer is controlled

by potentiometer R43 (l00 KQPOT). The ringer circuit is built around the tone ringer IC

KA2418 and a few discrete components. This part of the circuit has a low current consumption

to allow the ringer performance. The ringer IC has built in bridge rectifier with zener diodes to

protect against over voltages.

The IC generates pleasing tone composed of a high frequency alternating with a low frequency resulting in a variable frequency. The output of IC directly drives the ring. The DC voltage required for operation of the IC is generated from the ring AC signal. The ring signal, which is fed to the IC via the capacitor C4 and resistor R41. The supply voltage is filtered through

capacitor C43. The current is limited by resistor R41 thus limiting power dissipation in the IC. The tone frequency is determined by the external resistor R42 (1 5 K) and capacitor C42 (O.OluF) volume of ringer is controlled by potentiometer R43 (l00 KQPOT).

3.4.2 CURRENT LIMITER CIRCUIT:

Current limiter circuit is connected in series with the line at nodes ‘A’ and ‘B’. in a standard model this is implemented through two resistors placed R55(68Q) and R56(47Q). In this case short line current will be between 75 to 80mA.

3.4.3 DIALER CIRCUIT:

The dialing circuit is built around the tone/pulse switchable IC UM91214B and few associated components. Internal timings of the IC are derived via crystal (xl) of 3.58MHz crystal, ceramic resonator. It provides dialing pulse and Dual Tone Multi Frequency (DTMF).

The IC is provided by the supply from Vcc of TEA 1062A through diode D5. This diode prevents discharge of capacitor C22. During on hook, zener diode Z21 limits the supply voltage to safe operating region of the dialer IC. During on hook, IC is powered through diode bridge DlOl-D104 and R21. The hook condition of the handset is detected by HK input (pin 1). Off hook provides bias to base Q2l through R29 and R30. Q21 conducts and pulls HK to low. The IC derives its timings from 3.58MHz Quartz crystal or resonator connected to pins 3 and 4. The row outputs and column inputs are connected to the keyboard. The default-dialing mode selected through mode - in (pin 2) via mode switch p/t. if mode - in pin is grounded through this switch tone mode will be activated and if connected to Vdd, pulse mode is activated. In pulse mode,”*h’ key used to switch dial mode to tone mode from pulse.

In normal state, DP (pin 11) and mute (pin 8) are in high state. When a key is pressed, the mute pin changes to “low” state. This makes mute input of TEA 1062A (PIN- 12)”LOW” and in turn it mutes the receiver and transmitter amplifiers.

The dial pulses are transmitted from DP (pin).Normally transistor Q25 is off which puts transistor Q24 on. Conduction of Q24 put transistors Q22 and Q23 in conducting mode thus, circuit, drawing current from the line. During pulses on/off interrupting loop current for pulse break time and making loop during pulse make time. Number of pulses transferred on line depends on the key number dialed. At the end of pulses the mute output is switched to “high” so that the speech circuit is connected again. Make/break ratio is set to 33.3 to 66.6 ms. Dial rate is 10 pulses per second.

In tone mode the frequencies according to CCITT are derived from a crystal oscillator. When a key is pressed, the DTMF tones are generated at pin 7. These tones are fed via pre scalar network R26, R27, C21 and C24 to speech (pin 11). The DTMF signal is set on the line after amplification by TEA lO62A. Dialer generates low mute signal during which turns OFF

transmit and receive amplifier, it is possible to hear DTMF signal as a confidence tone receiver.

The optional REDIAL key facilitates 12-digit redial in pulse mode and 31 digits redial in DTMF mode.

3.4.4 SPEECH CIRCUIT:

Speech circuit is based on low power and low voltage IC TEA 1062A. The power to the IC and its peripheral circuits are obtained from the line. Depending of supply pin (no.13) is by capacitors C3 and C4. The internal voltage regulator is decoupled by a capacitor C6. The circuit has an internal current stabilizer where operating level is determined by the line current and resistor R8. The regulated voltage on the line (pin 1) is determined by the line current and resistor R4. The circuit has symmetrical microphone inputs (pin 7 MIC +) and pin 6 MIQ. Electrets microphone is used in the circuit. The microphone gain is controlled by resistor RIO and set at about 48dB. Stability is ensured by capacitors C13 and C5. The cut off frequency is determined by time constant of RIO and CS.

The receiving amplifier has one input (pin 10) and a non-inverting output (pin 4). Dynamic type earpiece incorporated in the circuit. The receiving input fed to circuit via resistor R1 and capacitor C12 from the line. The gain of receiver is controlled by resistor R7 and set at about 37dB. Two external capacitors C7 and C8 ensure stability of receiving amplifier. The cutoff frequency will depend on the time constant R7 and C7.

Automatic line compensation is achieved through resistor R9. The automatic gain controller varies the gain of the microphone and the receiving amplifiers in accordance with the DC line current. The controlled range is 5.8dB, which corresponds to a line of 5KM for a 0.5mm diameter twisted pair copper cable.

The anti side tone network consists of R2, Rll and Z BAL (i.e., R3 + R13// C14) Suppresses the transmitted signal in the earpiece. The anti side tone network in the circuit attenuates the signal received from the line by 32 db before it enters the receiving amplifier. The attenuation is almost constant over the whole of audio frequency range.

3.4.5 PROTECTION CIRCUIT/COMPONENTS:

The design incorporates two levels of protection in the circuit. Level 1 protection is against surge voltages. The level 2 protection is meant to handle high voltages and protect the speech and dialer IC’s.

VARISTOR VDR1 VDR is used across the line terminals to protect the equipment from surges

that may occur or induce on telephone lines. This device discharges over voltage to other line

(up to 2KV with a pulse of 10/700 us) and protects the remaining circuit from damage. During

lightening or switching relays at exchange may generate high voltages on telephone line,

which may cause damage to telephone. These high voltages are clipped and surge currents

are by passed to other wire by VDR.

DC OVER VOLTAGE PROTECTION:

The level 2 protection against the DC voltages will prevent damages that might

happen to speech and dialer IC’s and other parts of the circuit elements. The Z1, Z22 and Z21

perform the functions by limiting the DC voltages to the safe operating voltage limits of the

circuit elements.

3.4.6 OTHER SPECIAL FEATURES: REDIAL:

The dialer IC has a last number redial memory register. The last number dialed

through telephone will be stored into the register. This feature will be available in both

modes of dialing. The feature is activated through’ Redial’ key.

4. PRINCIPLES OF TDM-PCM

Time-division multiplexing (TDM) is a technique used for transmitting several analog

message signals over a communication channel by dividing the time frame into slots, ore for

each message signal. In comparison, frequency division multiplexing (FDM) divides the

available bandwidth into slots, one slot for each message signalXl (t). The important features

of TDM are illustrated in the figure below:

Four input signals, all band limited to f(x) by the input filters, are

sequentially sampled at the transmitter by a rotatory switch or commutator. The switch makes f(s) revolutions per second and extracts one sample from each input during each revolution. The output of the switch is a PAM waveform-containing samples of the input signals

periodically interlaced in time. The samples from adjacent input message channels are separated by T(s)/M, where M is the number of input channels. A set of M pulses consisting of one sample from each of the M-input channels is called FRAME.

At the receiver, the samples from individual channels are separated and distributed by another rotary switch called a distributor or decommutator. The samples from each channel are filtered to reproduce the original message signal. The rotary switches at the transmitter and receiver are usually electronic circuits that are carefully synchronized. Synchronizing is perhaps the most critical aspect of TDM. There are two levels of synchronization. Frame synchronization and sample (or word) synchronization. Frame synchronization is necessary to establish when each group of samples begins and word synchronization is necessary to properly separate the samples within each frame.

Direct PAM may transmit the interlaced sequence of samples or the sample values may be quantized and transmitted using PCM. Time-division multiplexed PCM is used in a variety of applications, the most important one is PCM telephone systems where voice and others signals are multiplexed and transmitted over a variety of transmission media including pairs of wires, wave guides and optical fibers.

TDM-PCM TELEPHONE SYSTEM

A 24-channel TDM multiplexer is used as the basic system, known as the TI carrier system. Twenty-four voice signals are sampled at a- rate of 8 KHz and the resulting samples are quantized and converted to 7-bit PCM code words, An additional binary bit is added for synchronizing purposes at the end of every group of twenty four 8bit code word another additional bit is inserted to give frame synchronization. The overall frame size in the ti -carrier is 193 bits and the overall bit rate is 1.544 M bits\sec.

The Tl system is designed primarily for short distance and heavy uses in metropolitan areas. The maximum length of the Tl system is now limited to 50 to 100 miles with a repeater spacing of 1 mile. The overall T-carrier system is made up of various combination of lower order T carrier subsystems designed for accommodating voice channels, Picture phone service, TV signals, and (direct) digital data from data terminal equipment, In additional to using metallic cable systems for transmission, optical fibers with repeaters have been used to transmit binary data at speeds of 1.5, 3.6, 45 and 274 Mbits/sec corresponding to the speeds of the digital transmission hierarchy.

5. THE 3000 LINES TOWNSHIP TELEPHONE EXCHANGE

INTRODUCTION: The 3000 lines electronic exchange installed at the town ship. The exchange is supplied and installed by SIEMENS-GERMAN technology. The HIPATH 4000 is designed initially for 3000 subscriber is capable of expanding beyond 5760 lines at later by adding requisite equipment. The exchange is provide with 120 PRI- junctions for interacting with the 3000 line electronic exchange in the plant and 30 channel E-1 connectivity for DID from BSNL network. The Exchange can act as local and transit exchange to facilitate interconnection of the above Exchanges. The exchange is also provided with hot lines, 104 analog long lines, and 48 digital lines.

TOWNSHIP TELEPHONE EXCHANGE HIGHLIGHTS : MAKE : SIEMENS

MODEL : HIPATH - 4000

CAPACITY : 3000 Lines expandable up to 5760 lines

CONFIGURATION :

ANALOG SUBSCRIBER LINES : 3000 (1200 ohms)

DIGITAL LINES : 48

ANALOG LONG LINES : 104 (3000 ohms)

LD –TIE LINE TRUNKS : 110

E1 –IN COMING TRUNKS : 30 Channels

HOT LINES : 50

PRI- TRUNKS : 4 x 30 =120

FEATURES :

IP- COMPATIBLE

ISDN – EXCHANGE

OFC – ADAPTABILITY

E1- ADAPTABILITY

REMOTE MAINTENACE INTERFACE

LAN – CONNECTIVITY

IVR – SYSTEM

CALL BILLING SYSTEM

REDUNDANCY

SINGLE CONTROL UNIT

UNIVERSAL SLOTS

PENTIUM PROCESSOR

FACILITIES( To Users) :

AUTO CALL BACK ON BUSY / NO ANSWER

WAKE-UP / REMINDER ALARM

CALL PICK-UP

DO NOT DISTURB

CALL FORWARD

CALL TRANSFER

8- PARTY CONFERENCE

30-E1-Channel (I/C)

TELECOM NETWORK IN TOWNSHIP :

Township Telephone Exchange is physically located in sector-7 area of township and is connected to Plant Exchange (PLX) through 120 numbers of PRI and 60 numbers of LD tie / trunk lines. These two exchanges are connected through 4-PRI channels 60- both way auto-auto type LD trunk lines. The numbering scheme used in these two exchanges is a closed numbering scheme and consists of 5 digits. There is no need to dial any prefix or suffix for dialing any number in township and plant areas. The telephone numbers in township exchange are in 86000-88999 range and in Plant exchange it is 21000-22999.

Township Exchange is also connected to BSNL network by a 30 channel Incoming E1 stream. Through this is E1 stream subscribers of BSNL network can land onto Township Exchange telephone numbers by adding a prefix of 288 before their five digit 8-series numbers of the township exchange.

TOWNSHIP EXCHANGE

PLANT EXCHANGE

BSNL EXCHANGE

120- PRI + 60 LD Tie

BLOCK INTERCONNECTION DIAGRAM OF 3000 L HIPATH-4000 EXCHANGE AND ASSOCIATED EQUIPMENTS VSP-TOWNSHIP

440 V OLTS 3 PHASE INCOMING

POWER SUPPLY

CUBICLE

DC SWITCHING

CUBICLE

SWITCH MODE RECTIFIER-UNIT-1

VRLA -BATTERY BANK -I

SWITCH

ADMIN &MAINTENANCE-

CONSOLE

MAIN DISTRIBUTION FRAME

SWITCH MODE RECTIFIER-UNIT-2

VRLA -BATTERY BANK -2

48 V DC VOLTAGE

As shown in the figure, the Township Exchange equipment mainly consists of the following equipment:

AC Incomer unit DC Power Supply Equipment Switching equipmentMAC ConsolesMDF equipment

5.1. AC Incomer unit: The Exchange is provided with 440V Ac, 3-ph power supply through two different feeders one from MRS (APSEB) and other one from TPP direct. These feeders are swappable whenever required depending upon the power availability. Incoming power to Power plant is supplied through these feeders and through a lever switch mechanism for each of the two SMPS units separately.

DC Power Supply Equipment: The power supply unit basically converts the available AC power (440 V AC, 3-phase) into 48 V DC. AC power is given to the SMPS rectifier units through a switch and a fuse cut – out assembly.

In Township Exchange the Power Supply Equipment is AMAR RAJA make and consists of:

2 no of Switch Mode rectifier units that is SMPS based Power supply units designated as SMP-1 & SMP-2. Each unit is having a CSU and three rectifier modules of 100 Amps capacity each, connected in parallel. The CSU has a display unit which displays the various parameters like Voltages , Currents , Alarms and battery status etc., The exchange normally draws a load current of 40 Amps approximately.

1 no of 600 Amps Manual DC switching Cubicle unit consisting of knife-switch arrangement is provided and is connected to the existing power plant and battery banks. In the supplied Manual Switching Cubicle unit, provision is there to connect / disconnect SMP1, SMP2, Battery bank-1 & Battery bank-2 using simple knife edge switches in any combination. The Load terminal of the supplied Manual Switching Cubicle unit is

3000 LINES TO FIELD SIDE

permanently connected to the exchange load. Also the supplied Manual Switching Cubicle unit is housed in a separate compartment and segregated from others.

In the event of mains power failure the Exchange will be automatically connected to battery supply without any interruption.

1 no of Manual Switching cubicle, which is provided to select the SMP units and batteries as and when required. All the connections from the SMP1&2, Battery 1&2 and the load (Exchange) are terminated in this unit. Selection of SMPs and Battery can be done by using two switches provided on the front panel.

2 no of VRLA Battery Banks ach 1000 Ah capacity are connected in float with the load.

The electrode reactions in all lead acid batteries are basically identical. As the battery discharges, the lead dioxide (positive active material) and the spongy lead (negative active material) both react with the sulphuric acid (electrolyte) to form lead sulphate and water. During charge, this process is reversed.

In VRLA batteries, the oxygen generated at the positive plate is transported in the gaseous phase through the micro porous Absorbent Glass Mat (AGM) separator to the surface of the negative plate. Here the oxygen gets reduced by reacting with the charged active material i.e., the spongy lead of the negative plate; thereby the formation of hydrogen gas is effectively suppressed. Consequently, the VRLA battery does not lose any water and therefore, no topping up is required. This is also known as the Oxygen Recombination Process.

Amara Raja Hi-Integrity Power Stack batteries come with self-resealing valves that release excess

gases into the atmosphere in the event of overcharging. Therefore, complete safety is ensured,

hence the name – Valve Regulated Lead Acid batteries.

Operation:

Amara Raja Hi-Integrity Power Stack VRLA batteries have to be charged only in constant

potential current limiting mode. The charging current is to be limited to a maximum of 20% of the Ah

capacity of the battery. Recharging is to be done immediately after a discharge. A logbook should be

maintained for recording all discharges. Further the charger/power plant should be compatible for

charging. Charge voltage settings should be as follows:

Recommended voltage settings:

Mode 15-32ºC Above 32ºC Current Limit Set (Amps)

For 24 cells Single cell 24 cells Single cell

Min. 10% - Max. 20% of

Battery Ah Capacity

Float 54.0 V 2.25 V 53.5 V 2.23V

Boost 55.2 V 2.30 V 54.7V 2.28V

Note: a) Unless otherwise stated, limit charge current to 20% of rated capacity of the battery.

b) Maximum voltage ripple content permitted < 2% RMS.

5.3. SWITCHING EQUIPMENT:

Switching equipment is the heart of any telephone exchange, the town ship

exchange switching equipment is housed in 4 cabinets that are divided into

1no – CONTROL UNIT sub rack and

15 nos – PERIPHERAL UNIT sub racks.

The CONTROL UNIT sub rack consists of all the control cards, Hard disk drive, MOD drive and power supply units for the sub rack

The PERIPHERAL UNIT sub racks consists of all the line cards , trunk cards , ringer cards and power supply units.

All the cabinets are fed with individual –48 V, DC supply from the bus bars

through individual MCP –switches. The –48 V supply is wired to all the sub racks in the

cabinets internally on the back panel mother board. Also earth connectivity is extended to all the

cabinets from the earth pit. There are 2 nos of Power supply units on both sides of each sub rack ,

out of which one is Working and other one is Standby .The PSU ‘s in the sub racks derives the

different voltages of +5V DC , -5V DC,+12 V DC and –12 V DC from the available –48V DC.

CALL PROCESSING:

The total call processing or communication between any two subscribers is basically divided

into two parts:

a) Signaling

b) Speech transfer

Signaling part:

The processor continuously monitors all the lines for any loop in pre-determined time intervals

(milli seconds). The various sequence operations that takes place during signaling are:

When any of the subscribers lifts his telephone hand set, the loop will be detected by the

exchange and the dial tone will be switched.

Processor collects the digits dialed by the subscriber.

Digit analysis(1st digit) will be done by the processor so as to route the subscriber to his

destination number

If the destination number is busy or off-hook the processor switches the busy / engage

tone to the originator number

Ringing current will be passed to the destination number

Ring back tone will be switched to the originator number

Processor continuously monitors the destination for his response to the ring

Once the destination party lifts the receiver the processor has to cut-off the ringing current

as well as the ring back tone.

All these above mentioned activities are part of the call processing and come under

signaling part of the call processing.

Speech part:

The subscriber line card SLC consists of 24 ports / circuits .Each port is for one telephone

number.

The various sequence operations that takes place during speech part are:

The analog electrical voice signals from the telephone hand set transmitter of the

originator number / destination number reaches the SLMA card in the switch.

The analog speech signals are then converted into digital form by using A/D converters.

Digital speech signals are sampled by Pulse Code Modulation (PCM) coding

The PCM coded speech information is further sampled.

Sampled speech signals are Time division multiplexed (TDM)

From the available TDM signals the processor identifies the originations address and

destination’s address, then switches A’s speech to the B’s circuit and vice versa.

The TDM signals in the respective circuitry are demultiplexed, PCM decoded, converted

from digital to analog form.

The analog speech signals of originator / destination are transferred to their receiver circuit. Thus the communication takes place between the calling party and the called part

4. MAC CONSOLES:

For MAN MACHINE INTERFACE:

The Exchange can be programmed from a Personnel computer (PC) which is connected to it by a

serial port / a LAN port. The software used for MMC is called “COMWIN “which runs in Windows

Operating system environment. The interaction is of command prompt type and not a graphical user

interface (GUI) based. By using this COMWIN application on the MMC PC programming and diagnosis

is being done.

For CALL BILLING:

All the out going calls or originations can be recorded into a PC with the help of this system. By

using a software called “ESCAPE”, the call billing PC records

All the originations call numbers

Time of origination

Duration of the call.

This system is provided to prepare the call billing extension wise for all the call originations

within the exchange. A dedicated PC is assigned for this system to monitor all the outgoing calls.

Malicious calls can be traced with the help of this system.

For IVRS (INTERACTIVE VOICE RESPONSE SYSTEM):

By dialing a code (174) the time is announced by this system and also by dialing 198, telephone

complaints can be lodged with the help of a voice prompt. All these complaints will be stored in a

database in the PC which dedicatedly assigned for this system.

5. MDF – EQUIPMENT:

MDF stands for Main Distribution Frame where all the subscriber lines and junction

lines from the Exchange are terminated on one side and field cables on other side. This

facilitates the jumpering of any number to any location as per requirement and also to isolate

Exchange side from the lie side to identity the fault. It provides protection to exchange by

employing PTC and GD tubes. PTC is Potential Temperature Coefficient i.e., it has a varistor

where its resistance increases and opens beyond certain current in order to protect the

subscriber card from drawing excess current. GD tube is a gas discharge tube (pin 3 ), which is

kept across A to earth and B to earth. This protects the exchange against high voltages due to

lightning. HT induction, foreign potential etc., by the action of gas ionization in GD tube

beyond 100V AC / DC and grounds the external voltage.

The Exchange side of MDF consists of six columns of hundred pair module blocks

each. There are six rows per column providing 3,500 cable pair terminals. Each hundred pair

module consists of 10 numbers of ten pair disconnection modules. The subscriber lines are

terminated in module blocks from Kl to K33, the long subscriber lines in block LI, the junction

lines in the blocks JI and J2, the hot lines in HI and H2 blocks respectively.

The line side of MDF consists of twelve columns of hundred pair module blocks each.

There are six rows per column catering to 7200 cable pair terminals. Each hundred pair module

consists of 10 numbers of ten pair disconnection modules. All the line side cables are

terminated in the blocks numbered from Ml to M72.

Automatic Line Testing Equipment (ALTE):

The MDF is provided with Automatic Line Testing Equipment (ALTE). It is a PC

based system through which the testing of the subscriber is done.

The following tests can be performed with the help of ALTE.

Foreign potential (AC / DC) in limb A.

Foreign potential (AC / DC) in limb B.

Insulation resistances of limb A with respect to earth.

Insulation resistances of limb B with respect to earth.

Insulation resistances between limb A and limb B.

Capacitance.

The measured values are compared with the already initialized values in the database and the

line is declared as pass or fail.

Provision is also provided to test,

A single line.

Sequentially on group of lines.

Sequentially on number of line groups.

Sequentially on all lines.

Or selection of required test is also possible.

The MDF is main distribution frame where the cables from the field side and the exchange

side are terminated. In township exchange KRONE –MDF is being used to terminate all the exchange

cables. All the dial tones from the exchange are available in the Krone MDF which is provided with

IPM s so as to protect the exchange equipment from the external high currents and voltages. The dial

tones are extended to the field side MDF via IPMs and jumper wires .Similarly all the trunk circuits are

available in the Krone MDF and these trunks are further connected to PLEX trunks / BSNL trunks in

the MDF.

Main Distribution Frame (MDF) is of four thousand (4000) port capacity and equipped with

40 no of 100 pair CT blocks with 11 way back mount frame and 2/10 disconnection modules mounted

on a painted, prefabricated steel structured frame and seamless interface for terminating exchange

cables & field cables, provided with hooks & rings for jumpers, with Integrated Protection Modules

(IPM)s which consists of PTCs and Gas Discharge Tubes for all the ports (Lines, Trunks) of KRONE-

make.

The MDF is provided with cable connections in the rear, channels for running the cables,

twin insulation Displacement type contacts, test plugs, front access to jumper connection tags/ferrules,

replaceable contacts ,rubber floor mat covering entire MDF area etc.

SIEMENS HIPATH 4000 EXCHANGE BLOCK DIAGRAM:

DIFFERENT TYPES OF CARDS USED AND THEIR FUNCTIONS:

CARD NAME FUNCTION

LTU-1LTU-2LTU-12LTU-15

SLMA 24 24 – port analog subscriber line card

SLMAR 8 – port long line card

TMLR2 2 – port LD trunk card

TM2LP 8 – port CO trunk card

RGE Ringer card

SIUX Tones card

LTUCX LTU – interface card

DPC-5 Processor card

SICOE Tones & DTMF card

MTSCG Clock generator

HUB C LAN connectivity card

HDD / MOD Hard disk drive / Magneto optical disk

5.3.2.FUNCTIONAL DESCRIPTION OF CARDS USED:

DPC5:

The data processor controller 586 with local area network (DPC5) board is a CPU PentiumAMD K6III+/400 central processor. It has a clock speed of 400 .vtHz and has 256 MB of local memory. It also provides 512 KB of flash memory, which is used by the firmware loading process. In the HiPath 4300, the DSCX board is the processor; in the HiPath 4500, it is the DPC5 board. For upgraded systems, older DPC5 boards require a second 128MB module.

SSD indicators are located on the front panel of the board The DPC5 front view and DPC5 side view provides connectors and switches for resetting the board, testing the board, and port functions.

QDCL:The quad data communication link (QDCL) board provides the signaling

interface (HDLC protocol) between the LTU shelves and the central data processor (]JP) in the

HiPath 4500 system. The HiPath 4500 SWUs (redundant and non redundant) use the QDCL

board to interface up to 15 LTUP or LTUE shelves respectively and provide a signaling

interface to the service unit. The QDCL board (Q2113-X100) has identical functionality to the

Q2113-X and doubles the throughput. The QDCL serves 16 bidirectional HDLC links (15 LTU

+ 1 SICOE). The communication interface to the DP is realized with a Dual Port RAM external

(DPRe), which allows independent and asynchronous access from the DP by means of

Multibus and from inside the QDCL by means of the Local Bus. See Figure 3-43. This concept

results in a partition of the QDCL board into one part which processes the Multibus interface

(Central Message Processor [CMPJ) and a second part which processes the HDLC interface to

the peripherals ( Line Processor LP). The two processors (CMP and LP) communicate by

means of a Dual Port RAM internal (DPRi). Figure 3-43 QDCL, Position in the HiPath 4500

(Simplex Mono) System.

SICOE:

This section describes the function of the signaling unit plus conference extended

(SICOE) board. It also provides procedures for removing, replacing, and verifying this board.

MTSCG:

The memory time switch with clock generator (MTSCG) board is a dual function board

in Hi-Path 4000 systems which provides memory time switch and network clock generator

functions. . The MTSCG board provides the voice data highway network switching function.

The switching network controls the voice data highways that carry the flow of information

through the system.

Voice data highways provide the communication channels between the switching

network, the LTUW shelves, and the service unit. The SWLJ board and common control

boards control the MTSCG board over the multibus. The MTSCG provides:

Four voice data highways to each of the first 7 LTUW shelves

One voice data highway to the SIU function of the SICOE board

Three voice data highways to the conference function of the SICOE board

Cross connect circuits that provide the SICOB board access to 32 highways for

extending the switching network

Ring Generator

The ring generator (RGMOD) can supply different ring currents depending on the

country setting and a 150 Volt direct current (Vdc) message-waiting voltage to analog

telephones attached to line interfaces in LTUW and L8OX shelves.

Interface to the Switching Network:

PCM Highways (interface to LTUCE): The SLMA2 has access to 128 time slots on four PCM

highways in the LTUCE shelf. Each highway has two unidirectional port HIO,F113 / ringing

signals, different ring generators are necessary. The timing for ringing is configurable and part

of LW data. The RING Signal Supply path reference potential is chosen by the RING.

Relay (K1). The two types of ringing are specified as:

Battery referenced ringing: typ 85Vrms, 20 Hz

Ground referenced ringing: typ 85Vrms, 25 Hz or typ 65 Vrms, 25 Hz

The line is fed with 1310 Ω source impedance The ring voltage is applied to and turned

off from each subscriber line near the zero-voltage crossing point by the LW to minimize the

impulse noise.

LTUCX:

The line trunk unit control extended (LTUCX) board has twice the number of speech

highways as in the former LTUCE board. It is supported for a standard LTU shelf by adding

new 2x4x2 MB highways (HWY bundle F 256 TSL) to the already existing 2x4x2 megabit

highways (HWY bundle A = 256 TSL). The result are 16x2 megabit HWYs 512 TSL. (Time Slot)

As an LTU shelf is devided into two shelf halfs, each shelf half supports 128TSL of bundle A

and 128TSL of bundle F. The additional speech highways can only be used by boards which

support this feature (for example the DRJ-N2 and DIU-N4 boards). Within the board

configuration it is determined if the board uses the standard speech highways or the

additional ones. Simultaneous use of all highways is not supported with this feature. You can

now use a few new boards (to access additional highways; reservation of many TSLs for every

board; for example, DIU-N4 128 TSL) with a greater number of old boards (only access to the

standard highways; reservation of few TSLs per board) together in the same shelf in a non

blocking configuration.

Prerequisites

The LTUCX board is configured and plugged into a peripheral shelf. Additional speech

highways are connected by means of an additional LTU cable from the common control unit

(CC) to this LTUCX board. For duplex systems, an additional cable is required from the active

CC and from the standby CC to the LTUCX. Only the speech highways are used in the

additional cables, not the HDLC signalling. The HDLC signalling is done only through the

standard LTU cable. To assign the additional LTU cables to the standard LTU an Overlay LTU is

configured. The Overlay LTU reserves the additional LTU cables. Peripheral boards cannot be

configured for the Overlay LTU. The LTUCX board doubles the number of speech highways for

a shelf.

.

Hard Disk Drive:

The hard disk drive functions as the mass storage device for system, application, and

database software. The hard disk drive and MO-disk drives are mounted on an SD3NX drive

holder that is installed in a single slot on the shelf (slot 22 for HiPath 4300 and slot 19 for

Model HiPath 4500).Hard Disk drive Connectors. The hard disk drive have one SCSI and one

power connector. A SCSI ribbon cable connects the hard disk drive to the disk drive holder’s

electronic board (see Figure 5-13). Mount the hard disk on the disk drive holder and install

the drive holder into one of the following:

HiFath 4300—CC8OF

HiPath 4500—CCDAX shelf

FEATURES IN TOWNSHIP EXCHANGE

90 WAKE UP SERVICE CANCELLATION 91 WAKE UP SERVICE REGISTRATION (91 Followed by Time in 24 hrs mode)

92 CALL PICK UP (92 Followed by telephone number)

93 DO NOT DISTURB ( Not activated ) 95 DO NOT DISTURB CANCELLATION 4 AUTO CALL BACK (ACB) 94 AUTO CALL BACK CANCELLATION 97 CALL FORWARD ( Not activated ) 98 CALL FORWARD CANCELLATION 99 COMPLAINTS DESK CALL CONSULTATION – On(IC or OG) call ,FLASH followed by telephone number CALL TRANSFER : On (IC or OG) call , FLASH followed by telephone number then ‘ON – HOOK’

the telephone THREE PARTY CONFERENCE : First step: On incoming call, flash followed by 2nd party telephone number

Second step: flash + ‘*’3

TIME ANNOUNCEMENT : DIAL – 174 AUTOMATIC COMPLAINT LOGON : DIAL – 198 Parallel telephone ringing : On IC call FLASH and ‘ON-HOOK’ the telephone – you will get ring

again FLASH is provided in all the new PB instruments or it can be done by just tapping of ‘Cradle

Switch’ of any telephone instrument

EXPLANATION ON FEATURES :

1. Three Parry Conferences:

While in conversion with another subscriber, if the first subscriber dials a code

Number of the third subscriber then all the three can have a conference together.

2. Auto call Back on Busy/No answer:

When a subscriber gets an engage tone after dialing a number, he need not dial all the

numbers again. Instead, he can just dial a code and put back the receiver in the normal

position. As soon as both the numbers are free, ring will be sent to both the parties and the

speech between them can be proceeded.

3. Wake Up Service Facility:

A local subscriber can set up alarm for the required time just by dialing a two digit

code and the required time at which he requires the alarm.

4. Call pick up:

This facility enables a subscriber A to pick up the call of subscriber B if he knows that

the instrument of B is in ringing state. This facility is availed by subscriber A by dialing a two

digit number of subscriber B, while instrument of subscriber B will be in the ringing state. If

the subscriber avails this facility, the instrument of subscriber B will be terminated from

ringing state thus transferring the call to subscriber A.

5. Do Not Disturb:

This facility is exercised by dialing a two- digit code. After exercising this facility any

subscriber who dials this number will get busy tone, till the subscriber exercising this facility

redials a two- digit cancellation code.

6.Call Forward:

I his facility enables a subscriber to forward all his calls to another local subscriber, for

example, subscriber A can dial a two-digit code and the telephone number of subscriber B

who is a local subscriber. Now all the calls of subscriber A will go to subscriber B. unless and

until subscriber A canals his call forward facility by dialing a two-digit code.

7. Call Transfer:

While in conversation, if the subscriber wants to transfer the call to a third subscriber,

he can dial, a code and telephone number of the third subscriber and after getting him,

replace the receiver.

8. Call Billing System:

All the out going calls are origination can be recorded into a PC with the help of this

system. By using a software called IIESCAPE** the call billing PC records a) All the origination

call numbers b) lime of origination c) Duration of call.

This system is provided to prepare the call billing extension wise for all the call

originations within the exchange. A dedicated PC is assigned for this system to monitor all the

out going calls. Malicious calls can be traced with the help of this system.

9.Interactive Voice Response System:

By dialing a code (174) the time is announced by this system and also by dialing 198,

telephone complaints can be logged with the help of a voice prompt. All these complaints will

be stored in a database in the PC which dedicatedly assigned for this system.

6.ADVANTAGES WITH THE MODERN ELECTRONIC EXCHANGE

Central exchange built in compact, space, saving construction practice.

Absolute operational reliability even in dusty of corrosive environment

No routine maintenance

Simple but comprehensive check of the entire system, from the central

exchange

Removal of faults by exchange plugs-in-cards

Simplex expansion of a central exchange due to its pre-wiring for acceptance of

additional plug in cards at a later stage

No skilled personnel required for trouble shooting, unless for troubles are

severe

A high grade electronic design and rugged mechanical construction ensure

reliable operation of a system, Inter stations can be expanded on a building

block basis, while central exchange can be put together individually

In this exchange is pair gain system is also available

7. CONCLUSION

In this modern age industrialization and automation, telecommunication plays a vital

role in coordinating the activities in achieving the assigned targets and accomplishing the

desired performance in any organization. However, miniaturization and faster accessing

modes developed using the latest technologies may further bring various technological

departments in the field of communications. With the advancements in electronics more

sophisticated exchanges with more number of applications may be available to the human

world thus, making the communication easier.

BIBLIOGRAPHY

1. Seimens Exchange HIPATH 4000 Service Manual

2. Communication Systems

- George Kennedy

3. Telecommunication Switching Systems And Networks

- Thiagarajan Viswanathan

APPENDICES

1.LIST OF ABRIVATIONS:

SLMA Subscriber Line Module Analog 24 port subscriber line card

SLMAR Subscriber Line Module Rural 8 port Long Line card

SLMO Subscriber Line Module , U p/o

interface

24 port -Digital Card

DIUC Digital Interface Unit Card E1-connectivity card

LTUCX Line Trunk Unit Control Extended LTU interface card

RGE Ring Generator Ringer card

MTSCG Memory Time Switch and Clock

Generator

Control Card for Clock

generation and memory

SICOE Signaling Unit and Conference &

Extension

Tones, MOH, DTMF etc.,

HUB HUB Controller LAN card

CC Common Control Control Processor Sub rack

ADP Administration & Data Processor Administration Control

QDCL Quad Data Communication.. Link Inter communication card within

the control unit

DPC-5 Data Processor & Common Processor Card

PSU Power Supply Unit Power supply unit

2.GENERAL FAULTS – DIAGNOSIS IN THE EXCHANGE:

Fault / Symptom Check DIAGNOSIS

No Dial tone complaint Check the DT at the krone MDF

…. if YES

Fault may be in the

IPM/jumper/field MDF

If NO If the DT is there in the previous

number and next number,

SLMA24 card may be faulty.

Replace the card.

Plant numbers not getting / plant Check the TMLR2 cards LED Fault in junction lines.

ADP

Administration & Data Processor

CCA / B Common Control Switch – A / B

DPC-5 Data Processor Common – 5 ( Pentium)

QDCL Quad Data Common Link

SICOE Signaling Unit with Conference & Extension

MTSCG Memory Time Switch & Clock Generator

LTU Line Trunk Unit

junctions not working status. If they are blinking

continuously..

Plug out and plug in the TMLR2

cards

ZERO – dialing not working Check the BSNL dial tones at the

krone MDF( 30 numbers ) If YES

Replace the TM2LP card

If NO To be informed to the BSNL

exchange