kwh meter reading wrongly

[kvkev]

I have a 2 element kwh meter which is reading only 20% of the expected calculated kwh value. It is connected to a 3.3 kv system via two residually connected ct's, and two vt's with a common secondary ground. I have a power analyser meter on which I have measured the input to the upper and lower elements of the meter. The ct's and vt's are outputing the correct values, but I suspect that the polarity of one or both of the ct's is wrong. How do I deduce which connections are incorrect? Can I change polarity at the meter, or do I have to do it at the ct's?
Regards,

kvkev

 

[busbar]

I am not sure what is meant by “…residually connected ct's.” The secondary polarity marks should, by convention, be “toward the source.” The secondary nonpolarity marks should be common and grounded. Assuming your organization has legal jurisdiction of the meter, this is a useful reference, but by default is based on ANSI systems:

http://www.themeterguy.com/Theory.htm

If there is a test switch in the instrument-transformer/meter loops—Smeaton’ s Switchgear and Control Handbook contains a discussion on simple meter troubleshooting. Also, the Edison Electric Institute’s Electricity Metering Handbook is a good reference.

If you thoroughly understand instrument-transformer hazards and safety, disabling each potential coil may be revealing. As for changes, for your own future sanity, start with standard connections at the instrument transformers and work from there.

Contact me off-board as needed tmp173@@nikola.com