Hi, i need to measure the inductance of a 70kVA linear reactor. What
are the most cost effective (e.g. cheap) options? I already measured it
with a bench LCR meter, but i do not trust the results; it read 5mH.
First of all, you might calculate what inductance is expected (to know
if 5 mHy is reasonable). What is the voltage or current rating and
operating frequency for this inductor?
By Xl=2*pi*F*L, 5 mHy would have a reactance of 1.885 ohms for 60 Hz.
So, it would be a 70kVA load if 363 volts were applied across it.
But if it has a large laminated core, it may not show its full, large
signal inductance with a very small voltage across it, as you have
with an LCR meter. The meter is probably also not be measuring the
inductor at 60 Hz. Of course, if it was truly a linear inductor none
of that would matter, but it probably isn't really.
I think a better way to measure it would be to apply a low voltage
across it with a step down transformer, measure the voltage across it,
and the current through it, and calculate the inductance that would
produce that ratio of voltage to current, which is the Xl.