Tracing DC Earth Fault

The best method I can suggest is one my wise old father taught me very early.

Divide and conquer.

By this he meant locate a point about equally dividing the run in half. Divide the circuit at that point and determine which half has the fault. Then divide that half also in half and test at that point. You will quickly be able to narrow the problem down exponentially.

In the case where shut down is a pain, pre-locate these points, and station a qualified testman at each point. Communication will be as important as the plan of attack.

With this general theory I have quickly identified the cause or at least cut out a very small domain of the circuit until the exact cause can be remedied.

Regards, CJM

Thanks CJMcGill, thats seems to be a very good idear.

Thanks CJMcGill

thats a cool idear, am gona give it a try,and i really know it's gonna work. However we have one of the generator panels we suspect the fault is being generated and we are going to isolate all the DC supply to these panels supplied from Battery system A, if the alarm clears then there is no doubt that this is the right place to start the battle,then we shall reconnect the DC and apply your wonderful idear of DIVIDE AND CONQURE shall be applied( what a good idear your kid's granny tought you(if you have any)....just kidding........

However this has to be done very quick cause i don't know what may happen if we get a second earth fault on the same system,surely an earth loop.

Thanks CJ, Peace B

Waco

Waco, please let us know what result you get.

We don't always get the satisfaction of hearing the result of the things we offer help with her on CR4.

CJM

Alright

I will give you feed back.

Thanks

Dear Sir,

You need to check the earthing to The battery Charger. It is not fair top connectr the battery cahrger with the main grid. Since any Earth fault will be on the other equipmnet will be reflected in the Battery Cahrger depending the sensitivity. Provide a sperate earth pit for the batttery charger you problem may get solved.

Alos, connect the centre deflection Ammeter aerth point to this earth pit.

Best Regards,

N.Suresh

Thanks N. Suresh

Our earthing is not that of earthing the negative rail by a solid link in order to prevent floating all over the place with respect to the earth but we use amore secure system the center-point high-impedance earth method, which utilizes a
battery earth fault alarm relay (BEFAR) . An earth fault on either the
positive or negative rail will cause a very small current to flow up the neutral (0 V)
connection. This will cause the BEFAR to operate to alarm and indicate which leg has
faulted. The supply however remains but this condition has to be attended to
before a second earth fault occurs.

However our progress on the earth fault is soon cause CJ gave us an idear,we managed to find the source (one of the Generator's panels),managed to isolate all the DC supply to this generator panels from DC system A with the earth fault and the Alarm cleared. So the next step is we are going to apply the DIVIDE AND CONQURE method from CJ,believe me will let you know cause we have already divided the circuits.

Thanks

Hi, CJMcGill

The results were good, we managed to find the earthfault just as you advised. One of the wires insulation was damaged due to the movements of a rack in rack out isolator. There are four MCBS in the panel that supply various control circuits, one of the MCBS was switched off and the the earth fault indication disappeared, then that's were we started to trace the fault, how ever we managed to identifiy it fro the teminal block when we removed the faulty circuit and the circuit was traced.

Now we are safe.

thanks.

Thank you Waco for the good news.

I can see also that you and your team have good trouble-shooting skills - BRAVO.

A pearl of wisdom from my father and your skills have saved a lot of very expensive equipment. I am thrilled to be a small part of that process.

Thanks again for the feedback.

Regards, CJM

The method of findind DC Earth fault is clearly explained here.

https://electengmaterials.com/how-to-trace-out-dc-earth-fault-using-multimeter/

Source: https://electengmaterials.com

Thanks & Regards