Power logger

[Bill Turax]

I was asked to determine if there is sufficient capacity to add a 200 amp 3 phase load to an existing 1200 amp 3 phase 480 volt MDP.

I hooked up a fluke power logger to the MDP to record the power for 30 days.

I am cretin that I connected the voltage and amperage leads correctly.

however the reading I was getting seems odd.

A and C phase were only pulling about 6 to 8 amps. however B phase was pulling over 160 amps. this MDP powers multiple transformers that step power down to 120/208 volt lighting and appliance panels.
I am not surprised the 3 phases are not balanced, however I do not understand how just one phase could be so much higher than the others... everything in the MDP is 3 phase. I did not note and heavy single pole appliances in the 208 V panels.

Just want to make sure a reading like this is possible and I did not goof something up when connecting the leads of the power logger.

 

[just the cowboy]

Something don't add up

Something don't add up

I would think just core losses on the xformers would be more than 6-8 amps even if the phases were unloaded.

 

[Cow]

When I hook up our logger, I wait for the logger to record a sample and verify the results with an amp clamp before leaving the premises just so I know it's working correctly.

Did you not amp clamp the wires while connecting the logger up?

 

[publicgood]

Did you put the correct CT ratios in the meter for all phases?