Can being in the same room as 13.6KV damage electronics? 2

[rmore]

I have a situation where we have 3 peices of identical equipment in the same room, which has 13.6KV feeds going into the room. All 3 peices of equipment worked fine, until they added a 2nd feed, then one of the units started experiencing intermittant program errors (even though it was not being poweed by the new feed). The units run off 460V which is derived from the 13.6KV power going into the room. We replaced the control board 4 times, and each board was subsequently damaged after a few hours of operation. When I get the control boards back to my shpo, they expoerience the same intermittant program faults, proving that the bus on the controllers was somehow damaged by being in the equipment.

My question is. Can simply being in the same room as a 13KV feed cause damage to a control board, even though the board is not being directly or indirectly powered by the 13KV feed?

If so, how?

and what are some things that can be done to help?

 

[mard57]

The only way is through electromagnetic interference from the 13.8kV. If your 13.8 kV cables are shielded with the shield grounded at one end only, it shouldn't be an issue to electronics. If shielded and both ends are grounded, potential sheath currents through the ground can influence the power supply feeding your control boards if connected to a common ground. If the 13.8kV cables are not shielded, the electric and magnetic fields are proportional to the rate of change of voltage...in this case, 60 hz is a very low dV/dt rate of change and the ampacity as well as the distance from the cables to the boards. Usually sensitive electronic circuit boards have shielding as well.

 

[itsmoked]

Perhaps your boards are too close to the "supply" as in the noise and transients existing on the 13.6KV lines. The supply for your boards likely have little impedance between them and the 13.6KV. Your units are experiencing much larger spikes and they are of much greater dV/dt than the boards probably expect or were designed for.

I suggest you quickly install some extra impedance in the form of some filters and certainly some MOVs ahead of your units (between the filters and your equipment) and see what results from it.

So, in a way the presence of the 13.6KV is the problem but not the way you're thinking, only in that it represents more nasties on the power.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[mikekilroy]

It would be very interesting to hear what physical size the room is and how the first and second added 'feed' wires actually run through it. And the position in the room of the 3 identical electrical control things and which one is failing. Details man! Bring them on. Might give some more clues.

Obviously when something works fine for a long time, then something is changed, and now there are failures, that something that changed, is likely the cause. With dimensions and locations someone may be able to point to the problem and thus a solution.

If you subscribe to the theory that ALL power is transferred in the electric and magnetic fields OUTSIDE the feed wires themselves (non inside the wires), your problem seems obvious, and location location location may be your answer.

http://www.KilroyWasHere<dot>com

 

[melspuds]

rmore
Is the new 13.8kV feeder incoming out of the room anywhere near your 480V controllers outputs outside of the room. Since it's a new install, the cable(s) shield maybe damaged.

An old lineman trick is to take a portable AM radio an follow the new 13.8kV feeder incoming from the room to is feeder location and continuity changing the AM dial full width of the frequency span (530-1700khz). If you have any leaking or arcing the radio will be static at that location.

Lineman have used this trick for years with where truck radios finding broken or arcing bushings or insulators. I have refined it to find bad cables, swgr, motors, ect. A $10 piece of test equipment.

Hope this will help,
Dave