Have seen this issue ( motor O/L testing ) generally discussed in past threads, but no detailed info on frequency and what standards (NEC, IEC, etc.) apply.
Could you advise where I might find IEEE / NEC / IEC, or other standards covering O/L testing and/or calibration.
We have Motor Control...
Thanks VLFit for your added comments. You raise an excellent point.
I had originally written this test procedure using AC for the same reasons you note. But others here with more field experience, advised the test gear is very large, and not always available in some of the Asian shipyards...
Thanks oldfieldguy,
Adding "...without the voltage being increased" will help refine the cautionary note I've included.
Many thanks to all for your excellant advice. A very valuable forum which I really appreciate.
Just wish I'd found you a month ago!
Gentlemen,
Thank you. Very helpful comments and data gathering techniques. If I may, a few final questions…
1. Failure Criteria: Is it fair to say the bus would fail the Hipot if the leakage current increases “exponentially” during any steady state voltage application? i.e. It indicates an...
Agreed; trending will be be helpful. I'll include this in requirements.
Earlier ZogZog mentioned monitoring for "upward knee" in leakage current. Does this typically show up only during the max voltage hold?
While I’ve witnessed many motor & generator hipots, I have never seen a bus hipot. My...
I will check NETS-MTS. The 20kV came from the ATS-1999, Table 10.2 for DC voltage. Now that you point out that ATS is for new gear, I would agree that 20kV is too high.
In "Electrical Power Equipment Maintenance and Testing" 2nd Ed. by Paul Gill, he suggests 20kV (Table 7.7) but does not...
By 'method' I assume you mean the procedure. I have spec'd slow 2000 VDC steps with 20 sec hold at each increase, and then record leakage. Hold at max. 20kV for 5 min. and record leakage every 60 sec.
I am not aware of anyhting more specific, or an IEEE ref to apply. Your suggestions?
Thanks...
An old Mechanical in need of help...
I have written a spec to cover inspection and DC hipot testing of 5kV switchger bus (excluding breakers.) 20 kV DC Hipot will only be allowed if Megger test confirms a minimum IR value of 100 Megohm at 40°C as per IEEE 43-2000.
Remaining issue I need help...
