Power Surges at Startup

Yes Jraef you have a valid point.But the problem is the system is a big system we are not allowed to operate and maintain(ok,it is a railway locomotive) and we are OEM suppliers.

Any suggestions you could give to deal with the surge would be useful

If the problem can not be solved with such a general suggestion, can it be called as best answer ?

Try asking anyone who gives a d...?

GA for you from me. I would like to remind the poster that cathode on the zener diode goes to the + side of the coil. I would also add a reverse biassed diode to handle counter emf when the coil releases... say 100v... also with the cathode to the + side.

I just happened to think... the zener diode will perform the same function so with a zener diode, you would not need the second diode. With a varistor (or MOV), I would add the second diode. I personally would use 1 watt diodes in either case.

Sincerely

Bill

I have used varistors inline to prevent power surges, they work great if you get the right type (NTC vs. PTC). You want one that has a resistance at room temp and than goes away once the current starts to flow (heats up).

Ohms laws will give you a ballpark guess for resistance.

V=IR, 74=0.16R, R=462 ohm, make sure it can handle the voltage/current and I would do a touch test to make sure it doesn't get too hot while in operation.

The downfall with varistors is it will only protect against the initial power surge. So you will have to wait for the varistor to cool before you re-power your system, usually this takes less than a minute but it depends. If this is a problem I would use a large diode, but I think the varistor would be safer and easier to install.

My Friend,

May we know, what is your DC power supply(DCPS)? 74V/0.16A is rated for EM Bell. I hope your DC Power Supply is 48VDC.

Power Surge is not the problem, since you have not mentioned, And, if your DCPS is 48VDC, then, you need only diode (suppressor) across terminal, to make it pure (at least) DC.

The way I look at it, your DCPS is not clean.

Check your DCPS.

hello there,

Thanks for the response.Let me confirm a few details.The system operates at 74 vdc and the DCPS is a generator which is a part of a diesel-electric locomotive.Well you wouldn't believe the basic flaws in a system created by such a reputed company,but then again i shall refrain from bringing up names.

It is impossible for me to make a correction in the DCPS.Yes that was a valuble suggestion and that would cut so many cost factors and solve so many problems.But that is out of my reach sadly.

So try something else that will work, then.

"A pessimist is someone who has a problem for every solution." _{- Anon}