ION 75/650's Current Inputs with 1A or 1V

[JamesAZZO]

We have a situation in a utility substation with CT’s ratios of 600:1A but the overcurrent max CT ratings are 1250A on the high side so we are looking just over 2A for the max current at the meter. I’m assuming we should be ordering the 1A calibration for the 1A CTs and that if it overruns the 1A (up to 2A n this case) that the meter will handle that as the inputs appear to be capable of up to 10A with this calibration.

Also, I would like confirmation that we can order the ION 7650 with Current Probe (Voltage) inputs 1V? Now, the real question is, can we use 1/3V / 0.333V CTs with this input order option? I was told yes once but I don’t know if I was understood since it’s not a 1/3V meter, but can I set the nominal to 0-.333?

John Straughn / James Clark?

[sesa50168 · Accepted solution]

Hi James -

Regarding the  600:1A CT question, the key point is the accuracy range of the current inputs of the meter.  The accuracy range for the Class 20 inputs, which is the typical range ordered for a 5A CT, is 50mA to 20A. The Class 2 input range supports 1A, 2A, 5A and/or 10A nominal inputs.  The accuracy range is from 10mA to 10A.  Therefore even if your 1A CT is generating a 2A output, the meter can handle it.  The correct order option is the 1A CT input, so that the meter will be calibrated for the potential lower range of current input associated with a 1A CT.

I confirm that the meter can be ordered to accept 0-1V current probe inputs.  I will advise separately regarding the compatibility with .333V CTs.

[JamesAZZO]

John - I need to know that answer about the .333V CTs if it supports 1V CTs.

[Yut]

If the meter is  5A option you should not have any problem install it into 1A  CTs, many time we install the ION7550/7650  5A meter with 1A CT they pass the test at site easily try it.