Friday, May 8, 2020

Overlap Stick Relay Circuits - OVSR And OVJN - Part 20

Overlap Stick Relay Circuits - OVSR 

Whenever Home signal is taken OFF(example S-12), 
the ALSR concerned drops 
thereby the point in the route, in overlap and in isolation are locked.

Point in the route are locked till the train clears them and the back lock tracks have picked up and the ALSR picks up. But Once the Home signals ALSR picks up, the locking effect on the Overlap Point is released thereby making them free, Which is undesirable.

So the question arises is How we do secure Overlap and also make it flexible for train operations?

Two scenarios will explain requirements of overlap locking clearly: 

  1. If starter is given the overlap points of Home signal are held further by its ALSR as they are in the route.
  2. Even if starter is not given , the overlap points should continue in locked position for specified time(120 sec) to ensure that the train has stopped in rear of starter, after which only the points shall be free.
For example 

If Home Signal S12-ALSR picks up after the train has cleared the back lock tracks and is still rolling on berthing track , overlap points beyond starter will become free if they are locked only by S12-ALSR which is undesirable. 

Thus OVERLAP should be secured by another relay OVSR which provides for safety as well as flexibility in operation.

OVERLAP is normally energized and drops whenever the reception signal is taken OFF leading towards the overlap.

OVERLAP relay is designated with starter number , beyond which the overlap is reckoned.

OverLap Circuit For S-12 over sand hump called as 6A OVSR circuit which is shown below.

6/4 B OVSR Example: 


- Requirement 6/4 OVSR ko Pick up karana hai?

- Complete Arrial of train.
- S12 ka overlap ka name starter k naam pe hoga i.e 4/6OVSR
- Shunt and Calling on signal ka no overlap.
- 12UCR drop -> Route Lock nahi hona cahiye.
- 12/C-12 ALSR pickup -> 12/C12 Signal Red hona cahiye or Complete arival ho jana cahiye.
- EOVNXR drop-> Cancellation overlap ka na kiya ho.
- Runthrough se yadi train jaye to -> Turant Overlap pickup hona cahiye.
- Train berthing track pe complete aane ke baad ya cancellation me he timer chalega.
- * -> holding path. 

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