Transformer Inrush Measurement

[ThePunisher]

We are setting up to measure a transformer's maximum inrush current. One of our testing contractor offered an equipment called: Dranetz PX5 recorder with 3 TR2500 clamps, memory card and software.

My question is a 5ms measurement enough to detect the transformer inrush with harmonics or do we need less than 4ms measuring capability?

 

[waross]

You may want to check the efficiency of the proposed transformer. They may be reducing the inrush at the expense of efficiency to the point that the losses are more than you can afford on an ongoing basis.
I may be wrong but it won't hurt to check efficiency as you evaluate the transformer.

Bill
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"Why not the best?"
Jimmy Carter

 

[ThePunisher]

Hi all,

In your technical opinion, will a 256 samples/cycle rate recorder adequate enough to measure a transformer peak inrush current?

Unfortunately, the clamps being used on all our recorders are of Rogowski Coil design and will not capture the DC component of the inrush. Due to time constraints, we are not able to outsource one Hall-Effect CT. Instead, we are looking into a "wide-band" Ferrite CT. Any concerns by experience on this one would be a good help for us.

If we do use the these "clip-on" current sensors and register a peak current on the recorder, is there any other way to approximate the DC component without tedious transient calculations. We had measurements on the same rectifier rating in the past. If the manufacturer claims that they are able to reduce the inrush from 15x to 1x FLA, can we look into it on the basis of approximation looking at the ratios?