ground fault detectors in automatic train control

It'd be in milliamps, wouldn't it?

Ask the D.C. MTA... I'm sure they'd have some interesting info as of the last few months

Dan - Owner

this is for automatic train control. The ground detector determines the ground leakage and alarms the maintainence crew when there is too much leakage. If it is set too high it will be too temperamental(something as little as rain could trip the alarm), if set too low it could cause the signal to turn red inadvertently which causes the trip switch to rise. The train engineer may blow through the red signal. Also, the trip switch will cause the breaks to lock. Im asking if there is a regulation in place that states what an appropriate level is to set the ground fault detector so it is neither too temperamental, yet will not allow too much leakage.

Ah, I see. My previous post was way off base. Disregard.

I thought train controls ran on 72V DC.

Does GFI even work on DC?



Mike Halloran
Pembroke Pines, FL, USA

Several aspects on this.

First. It is not about ordinary GFI (aka RCD), I think. Or is it?

Second. The ATC works (at least on most European railways) by detecting the wheel axles shorting both rails. The system uses low voltage and high current and usually some weird frequencies to make the function insensitive to ordinary traction currents and its harmonics. I can also imagine that DC is being used.

Third. Yes, there are DC GFIs. Bender has one.

Four. Need to know if you really mean detection of ground faults on the live rail (signalwise) or if you are asking about something else.

Five. If it is about detecting ground faults on the live rail, then I am not aware of a "standard" setting. Must be more than milliamps.

Gunnar Englund
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

Thanks for the education, Gunnar.



Mike Halloran
Pembroke Pines, FL, USA