Question On Mcb (db Trains)

Does anybody know why MCB must be set on "close" in order to work? The term "close" seems synonym of "off" but in real life it is switched on. Why? Does anyone know what there is behind this control? (electronic or mechanic point of view). This question is for all fuses of locomotives too.

 

By closing the MCB and the fuses, you close a circuit. The MCB is the connection between the pantograph (and the OHLE), and the interior of the locomotive. Closing the MCB ensures that power is provided to the drive system.

 

If you close a door, you got a full wall, if you open it, you have a hole in the wall and it's not a full wall anymore. This is about the similar logic of an electric circuit. As said above, the switches don't transport the current further when they are open, but when they are closed, both ends are basically connected, and the current can flow through the closed switch.

 

So in the expert db br 101, the question is the same for sifa and pzb/lzb valves too?

 

If you close the valve, the air does not flow through. If you open the valve, the air does flow through. And if you ask the Valve for half life three, it hides in fear.

 

No, with valves it's the other way around, they have to be open for the systems to work.
Easy to remember, electricity only flows when the circuit is closed, air, oil or water, for example, only flows when the valve is open.

 

For the PZB/LZB, Sifa and ETCS valves, it's a bit different. Basically every train protection system installed on the train has it's own valve on the brake pipe so that it can drain it and stop the train regardless of the situation. For ETCS it's electro-magnetic so that it's closed only when supplied with power but I don't know about the other ones.

The point is that if you isolate any of them, you remove it from the circuit and that type of train protection gets disabled (can't apply brakes anymore).

Also a fun fact. If you turn off the PZB/LZB breaker > The PZB/LZB system doesn't get power > PZB/LZB drain valve doesn't get power > it automatically opens (maybe electro-magnetic as well) > your brake pipe starts getting drained indefinitely. That's why you have to isolate these if you want to drive without a particular train protection.

 

Thank you everybody. Now it is more clear

 

Much simpler:



For a valve, imagine the current flow being vertical instead of horizontal, so it needs to be open to allow flow.