Third Rail or Conductor Rail System
Question
Q. For conductor rail system used for current collection system:
Question
Q. For conductor rail system used for current collection system:
- State its merit (any one) and demerit (any one).
- What is done to reduce the voltage drop at joints?
- Suitable system voltage.
- Third rail or conductor rail system is a method of providing electrical power to electric locomotive through a continuous rigid conductor placed alongside or between the tracks.
- It is basically used in a mass transit or rapid transit system.
- Third rail system is always supplied from the DC power supply
- Figure (A) shows the third rail system with all the necessary dimensions.
(A)
- They are placed at a distance of about 0.4 meter away from the tracks.
- They are cheaper to install as compared to overhead wire contact systems, as there are no structures for carrying the overhead contact wires and therefore there is no need of constructing over- bridges or tunnels for providing clearances.
- Apart from this, it presents electric shock hazards close to ground, so not applicable for high voltage above 1500 V.
- A very high current should be therefore used to provide sufficient power, which in result increases the resistive losses.
- Because of this reasons, it is applicable only for low voltage below 1500 V.
- It is cheaper
- It can be easily inspected and easy to maintain.
- The shoe must be placed on both sides of the locomotive.
- The shoe must be properly arranged or fixed.
- To reduce the voltage drop at joints special arrangement must be made at the joints to reduce u voltage drop and copper bonds consisting of short lengths flexible conductors are bolted or welded to the rails. They are not fixed rigidly to the insulators.