Electricpete I would agree that the the majority of the common mode current entering the motor terms gets to ground in the stator. The larger question remains, how to identify or separate bearing current from the stator ground current. I would expect the signature of the bearing current to be...
Is anyone aware of documented research which relates bearing life to the magnitude of rms or peak(pulsing) current? I can measure and reduce common mode current near the motor terminals and must assume that most of the common mode current in this location particularly the peaks (current...
my understanding is that large wind turbines are expected to develop about 33% of nameplate power on a continuous basis converted to KWH. If that assumption holds true you may be able to deliver 200 watts on average.
Neil
This is a cost/benefit analysis.
"Using multipulse rectification is usually the least expensive way to mitigate harmonics". Come on, line reactors are the least expensive way to mitigate harmonics. This analysis can't be made without costs, target THD and realistically you need to know the...
EEPROM,
I can't speak to breaker use as we don;t use them in this capacity. We build 508A panels all the time and we have a letter written by a UL Engineer that clarifys our requirement. We use 2 current limiting fuses in series, per phase. Both fuses are class T. The source side fuse is...
A 15hp 3 phase VFD can be supplied from a single phase source then provide a 3 phase output to the motor at 7.5hp. This is a fairly common application. Should work well as long as you don;t need to change voltage.
Neil
there is another possibility. If this is a 3 phase choke with a 3 leg core, then if the leads are grossly over sized by cross section, you can have a high amount of common mode current. Such a reactor will saturate in the yokes from this condition. Need to reduce the common mode current. This...
I'll qualify my statement by saying that the VFD cable we have test experience with was purchased around 10 years ago and frankly I don't know if it has individually shelded strands. But we did ground the shield and our results were that the overvoltage ringup was not as bad as the armored cable...
I think you will find a properly sized dv/dt filter with armored cable (again properly sized) to be a more cost effective solution. The problem with the VFD cable is that it is basically jus protecting itself. You will still get ring-up at the motor terminals. One of the really big problems I...
These transformer commonly see 250% of rated current for relatively short periods say 1.5 hours, mainly in the morning when everyone wakes up. Then in the afternoon again a high overload maybe 150-200% but lasting a few hours, then 10-20% for about 8 hours,... The oil provides a significant...
It's kinda like putting a 60w light bulb in a socket where previously there had been a 100watt bulb. The new bulb only draws 60watt regardless of the circuit and socket's ability to deliver 100w or more.
Neil
With regards to residual flux. This gets to my point about the likelihood of a transformer saturating much more quickly than an inductor. Inductors typically have much lower permeabilit, made so by air gaps. The air gap allows the residual flux to seek a very low level. Unlike transformers...
