ELECTRIC TRACTION

SYSTEM

Presented by:

ATUL GIRI

EN-E 4th year

1202721027

OVERHEAD

EQUIPMENTS This is an overhead wire of special cross

section. The contact wire is supplied at 25 KV; 50 Hz supply. AC voltage is trapped from contact wire by pantograph.

Stay Arm: It comprises of dia 28.4/33/7 mm (Small) size tube and an adjuster at the end to keep the bracket tube in position. It is insulated from the mast by stay arm insulator.

Bracket Tube: Catenary is supported from this member by catenary suspension brackets and catenary suspension clamp.

Register Arm: It comprises of dia 28.4×33.7 mm tube to register the contract wire in the desired position with the help of steady arm

Dropper is a fitting used in overhead equipment construction for supporting the contact wire from catenary.

Neutral Section is defined as short insulated dead overhead equipment separating sectors fed by two adjacent substations which are normally connected to different phases.

Short Neutral Section – Section Insulator and PTFE . The locomotive is switched off while negotiating the neutral section to avoid flash over at the time of exit and re-entering the live zone. For this, warning board at 500M, 250M and final board for switching OFF and ON are provided.

Neutral Section

SECTION

INSULATOR Section Insulator is a device installed along with the contact wire for insulating two elementary sections where the pantograph of the locomotive negotiates smoothly and maintaining the current continuity.

It is used in crossover, turnouts, maintenance pits and yard line, etc. During movement of locomotive pantograph, it first passes over the runner and smoothly glides to the contact wire on the other side without the break of continuity.

electrical continuity between contact and catenary wires

jumper

Jumpers provided between out-of-run OHE and anticreep wire as an anti-theft measure.

Booster Transformers

Booster transformers are used in electric railway AC catenary feeders to collect the return current from the rails and the earth to the return conductor.

Booster transformers are single-phase transformers with the ratio 1:1. They have low impedance values, but despite that, they must tolerate the stresses of short-circuit currents.

power ratings of booster transformers are 100-800 kVA. The nominal current is usually between 200A ...800 A.

Electrical Parameters of AC OHE system

Traction Supply Voltage:Nominal Voltage: 25kVPermissible Limits: 19.9kV to 27.5kV

Traction Supply Frequency:Nominal: 50HzPermissible Limits: 48.5Hz - 51.5Hz

Traction Transformer Rating: 13.5MVATraction Transformer Resistance: 0.179ΩTraction Transformer Reactance: 5

Power system installation

25 kV AC single phase

For traction substation (TSS) the incoming EHV supply is

220/132/110/66KV through protective equipment it can

be transformed by using traction transformer to 25 KV AC

single phases.

Spacing between TSS is 30 KM to 40 KM depending upon

the traffic (load).

To avoid load on one phase and balancing the incoming

supply grid, the section TSS is divided into sub-sector

through switching posts.

1. S.P:- Sectioning and paralleling Post.

2. S.S.P:-Sub-sectioning and paralleling Post

Sectioning and paralleling post (SP)

To facilitate the extension of traction power from one feed zone to half of theadjoining feed zone during emergency.

Parallel the UP and DN OHE in double the sections

Sub-sectioning and Paralleling post (SSP) Each section is subdivided into two or three subsection by the provision of SSP every 10-15

Km. This facilitates isolation of faulty sections.

To sectionalize OHE

To parallel the UP and DN OHE in double line sections.

POWER

TRANSFORMERThere are two traction transformer connected in parallel of same rating for the purpose of reliability the rating of transformer areCapacity: 20,000 KVA. Frequency: 50 HzFull load: 25 KV Preferred: 0.9Zero load: 27 KV

CIRCUIT

BREAKERS

220/132/110/66KV,double pole:- Minimum oil type- SF6 type

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit

25kv,single pole- Minimum oil type- SF6 type- Vacuum tube

Lighting arrestors are provided to protect every sub-sector against voltage surges.

Auxiliary transformers are provided at all the posts and also at certain intermediate points to

supply AC at 240 V, 50 HZ required for signalling and operationally essential lighting

installations. To ensure fairly steady voltage, automatic voltage regulators are also there,

where required.

Potential transformers are provided at the various switching stations for monitoring supply

to each sub-sector.

Equipments at switching sections

Buchholz relay is a safety device which is generally used in large oil immersed transformers (rated more than 500 kVA). It is a type of oil and gas actuated protection relay. It is used for the protection of a transformer from the faults occurring inside the transformer,

Control

Equipments A Remote Control Centre (RCC) is set up near the traffic control office on each

division having electric traction to work in close liaison with the traffic control

The RCC includes the main control room, equipment room, uninterrupted power

supply (UPS) room, remote control laboratory and battery room and is the nerve

centre of the traction power control.

To segregate the faults and to isolate the faulty section, the circuit breaker at

traction substation and interrupters at SP/SSP’s are being remotely control through

remote control centre

The following types of remote control equipment are mainly in use on

Indian Railways at present

Frequency modulated voice frequency telegraph (FMVFT): This equipment was in use for all electrification schemes prior to 1980. Being mainly all relay system, the equipment has become outdated although some remote control centers still continue to operate on this system

The FMVFT equipment has one send channel panel and receive channel panel. The equipment works on 24v dc battery power supply

Supervisory control and data acquisition (SCADA) systems withmicroprocessor: The SCADA equipment based on state of the art technology hascome into use after 1980. Considering the fast growth and development of computerbased equipment, newer types with enhanced capabilities are being introduced.

The SCADA equipment at the RCC is called master station while that of the controlledstation is referred as remote terminal unit (RTU).

SCADA

EQUIPMENTTRANSMISSION PATH:-

Underground telecommunication trunk cable is provided for transmitting the signals from and tothe RCC and controlled remote terminal unit.

REPEATER STATION:-Voice frequency repeaters are provided at interval of 40-50km to boost the signal and to make the

good the line attenuation. The amplifier gain at the repeater station is about 20db, with an equalizerincorporated to compensate up to 0.02db/khz/km.

MICROWAVE COMMUNICATIONIn some of the sections on Indian railways dedicated microwave channel at carrier frequency of 18GHz has been provided for the purpose of Communication.

OPTICAL FIBRE CABLEOptical fibre cable has also been introduced for communication in some section of Indian railways,which is also used for Remote Control equipment. Details of interface between latestcommunication system and the RCC/RTU equipment may be seen in the relevant technicaldocument.

UPS and Batteries

at RCC1. Dual stand-alone UPS system of adequate capacity to supply 240V A.C., 50 Hzsingle phase supply to the SCADA system at master station is provided. Both theUPS work in parallel sharing the load.

2. In case of failure of one the entire load is automatically taken over by the healthyUPS without affecting the working of the system.

3. In case of outage of both the UPS at the same time, the load of SCADAequipment is directly connected to input main though a static switch withoutany break.

4. A single battery is provided with both the UPS with adequate capacity toprovide the supply to various equipments is case of failure of input for 415V A.C.,50 Hz supply.

Pantograph is a current collecting device which is mounted on both ends of locomotive roof on insulator and collect the current from Over Head Extension and supply it to power system of locomotive at various speed and different climate/wind condition smoothly

Pantograph

The traction motor is a dc series motor, four pole or six pole, forced ventilated machine

arranged for axle mounting on sleeve baring and supported on the opposite by the

resilient suspension unit, transverse movement is limited by the flanges of axle.

These motors are axle hung, nose suspended type and are provided with grease

lubricated roller bearings for armature as well as for suspension.

Special provision has been made in design of the motors to ensure the locomotive

operates satisfactorily on flooded track, to max. Flood level of 20 cm , above rail level

Traction Motors (DC Series

Motor)

Rating: A traction motor has following ratings:Voltage - 285 volts Current - 980 ampere Speed - 360 rpm Power - 248 kw

Thank you