The sliding contact collector above the train collects the current from the overhead system and it is mounted on the roof of the train. This sliding contact collector should be able to balance itself at the various levels and various speeds (high or low). There are different types of collectors which are used for collecting the current but the most popular collector is the PANTOGRAPH COLLECTOR.
Types of collectors:
- Trolley collector:
In this type, the surface contact is obtained by two ways
- Grooved sliding contact filled with carbon
- Grooved gun metal wheel
Both of them are mounted on the light pole at the one end and the other end of this pole is hinged at a rotating base and it is arranged on the roof top of train. Springs are used for getting the contact pressure.
In tramways & trolley buses.
Two trolley collectors are used for trolley buses. The trolley collector works properly at low speeds, but at high speeds it can get separated from the contact wire.The trolley contact can be used up to 32km/hr. For changing the direction of vehicle the collector must be rotated at 180.
- Bow collector:
- It consists of a metal strip which is attached on the one end of two poles which are placed on the top of vehicle.
- The poles have enough length so that the sideways movement of the collector along the vehicle’s path is achieved.
- Here the springs are used for getting an upward pressure.
This system is also used in tramways.
It also reduces the risk of the collector getting separated from the conductors at high speeds also. And thus a bow collector has high speed than trolley collector.
- Pantograph collector:
- This type of collector consists of copper wearing strip which acts as contact surface.
- This strip is removable and when it wears off it is replaced with a new one.
- This copper strip is placed on pressed steel pan of the channel section.
- The springs help to support the channel section on a frame work of pentagonal shape.
- In electric trains
- Tram cars or trolley buses
It operates at a speed in between 100kmph to 125kmph. The current gets collected in the range of 2000A to 3000A.
It has many advantages over other types of collectors:-
- It operates in both the directions.
- The conductor and the collector separation risk are low.
- The erection of overhead network is simple.
- Its height can be adjusted accordingly by the will of operator.
- ELECTRICAL POWER SYSTEMS BY UPPAL , Sunil S RAO
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