Hello everest,
I suspect the bearing failures you describe have been caused by common mode high frequency current capacitively coupled from the motor stator - to rotor - to ground via the bearings.
This is an unfortunate and occasional consequence when VSDs are used. At 50/60Hz, these...
Hello GOSS,
That's good information.
I too have recently been involved in evaluating an energy saving device and have noted results near identical to yours ;-)
In addition, the other result I noted was the power factor improvement. For example;
0% Load, pf=0.24, energy saver enabled...
In addition to AS3000 for general requirements, see also AS/NZS3008 for conductor sizing relevant to the switchgear to be used, not just the current rating of the cables themselves.
Failure to refer to AS3008 can result in some unfortunate heating effects and switchgear failure (I speak from...
Also thinking out loud, assuming a single phase motor, my understanding is that during a single rotation, whilst outputing an average of 100% mechanical power, the 1 ph motor receives (approximately) +120% followed by -20% electrical power, resulting in the typically annoying vibration...