1.2 TYPES OF CONTROL (DEMONSTRATION) CONTD...
You must be wondering why another page. Reason is simple!! Most of the things were taught to us verbally during demonstration so there is lot to recall as well as write so it's inadvisable to keep such huge data on one page. So, let's start.
1.2.2 Traction Power control
This demonstration was basically about traction. How they control it and stuff like that. They have the remote control of every traction in their area through computers or Traction Distribution Control. I will now give you a circuit diagram and try to explain as much as I remember
 |
| Layout of traction system |
I will now explain some important things you must know
1) Red means that traction is live and carries current whereas green means it don't.
2) Green means that CB/BR is on whereas red means it don't
3) Yellow box means that traction line ends there.
They get their power from the power department of different states. Railway buys power from them. Now as you can see from the diagram they get it at 132 kV which they transform into 25 kV at which DC engine works. There are circuit breakers which protect the circuit from damage and bridging interceptors from which they control the power to each traction line. The traction line is divided into lines each of 40-60 km. Their are some reasons for that :-
1) To ensure that if one line breaks down others are there.
2) As we know power from electricity board is three phase so they give one phase to one division of traction and second phase to other division of traction and so on. It ensures that load is equal on each phase.
3) To make maintenance easy .
4) To reduce losses.
Bridging interceptors are used to control the power to each part of traction (lines). They are like relays which can be controlled remotely as well as manually. Power can be controlled by three ways
1) REMOTE CONTROL :- Control can be done remotely by traction controller. Traction controller can continuously monitor the whole traction networks via traction control circuit through their servers. So, they can control and monitor them remotely. For that the servers in traction controller office is connected to traction control circuits through means of Optical Fibre cable..
2) Station contains the facility to switch them off or on manually also.
3) Bridging interceptors themselves have a manual on and off switch which can be used if above two fails.
Let us talk about some challenges faced by traction control and how they tackle them.
1) One of the most important challenge is maintenance. Of course as you can predict wires requires maintenance. But you cannot shut down the whole railway network just for that. For example if the traction wires ahead of a train is cut or damaged, they cannot afford to stop the train for long duration. They have to do it quickly. USUALLY THEY HAVE MAXIMUM OF 50 MINUTES FOR THAT. Now we have to switch the power off in that part of traction for safety of maintenance personnel so they can work on it. (remember 25 kV one will be burnt to ashes ) . So they switch it off using bridging interceptors. The traction line is divided into divisions that can be taken as a line with two stations as their end points. The place where repair is to be done will be near to one of the station. So maintenance personnel will use the tracks to reach there, finish their work and return to the station. Until then no train can enter that part of line.
2) Second task is to manage the load on line. Now power allocated to railways is constant. That means voltage and current have inverse relation as P = VxI. DC engines don't work below 18 V i.e. they can only have specified no. of trains in each line. Besides, they cannot allow the current to be too high otherwise it can damage the traction. So they have to work with train control to manage trains .By now you must have an idea how much complex is to control trains.
3) Third task is to manage power itself. For example :- If two electricity board A and B are supplying power to two set of lines. If A fails due to some reason to supply power then power from B has to be extended as railways cannot afford to stop the trains for it. They also have to take the above two factors into consideration while extending power from one line to another.
Ok Let's end this page here I will talk the rest in other pages
No comments:
Post a Comment