Cable Shielding Rules

I believe this question has been answered previously on CR4.

http://cr4.globalspec.com/thread/30266/power-control-shielding

http://cr4.globalspec.com/thread/24066/Grounding-Cable-for-Instruments

and in others that I cannot seem to find immediately (they are there).

What's the application (as there are special cases such as IT and instrumentation)?

Is the shield terminated at both connector ends?

The application is a power cord plugged into 3 phase 400 Hz 115V mobile power generator.

If the shield is supposed to help you meet aerospace or military type EMI requirements (RTCA/DO-160 sections 20 & 21, MIL-STD-461 RE102), then indeed you terminate the shield at both ends. If you are worried about 400 cycle coupling to nearby instrumentation lines, you can ground at one end only, and it won't matter which. If you are grounding an instrumentation shield in order to protect it from 400 cycle interference, then you should ground that shield at the same end of the cable that the circuit is grounded. If you tell me that both ends of the instrumentation circuit are grounded, then I tell you that you have a big problem!

This power cable is not grounded at either end. However it connects to a tester and the tester is grounded. The mobile power generator is not grounded. According to your info I have a feeling my 3 phase 400 Hz power cable with neutral and ground is not up to snuff.

The power cart isn't grounded ?!?!?! Say it ain't so! That is rule #1 with 115 Vac power. That's safety - not EMI. You can flout EMI rules and fail radiated emissions and susceptibility. You flout safety rules and people get hurt.

emc_c

P.S. It's quite secondary, but you have yet to identify what your shield is supposed to accomplish for you. When you do that, we can nail down the shield grounding technique.

After you get that power cart grounded!

The shielding is on a power cable that supplies 3 phase power to lab equipment. The equipment is handled by humans. The lab equipment is grounded. The power generator is not grounded.

So I guess the shield is picking up ground from the lab equipment. If the power cable shield was tied to it's safety ground line which flows back to power generator that is NOT grounded then ..nothing. So instead it picks up ground at the equipment.

OK I think I am getting this.. maybe...

You still have not identified the purpose of that shield. Lacking a purpose, one cannot make a good recommendation. Or another way of looking at it: without a defined purpose, any approach will suffice. If you don't know where you are going, any direction will do.

emc_c

P.S. A ground on the test equipment does nothing in terms of clearing a fault if the generator is not referenced to the same ground.