Bizarre Power Factor Problems 2

[Eldon1955]

Our thermography dept. recently brought my attention to a 45 KVA
600v Delta:600/347v Wye Dry Core transformer regarding excessive heating.I did a power survey with a Northwood Interlogger.Results showed slightly low voltage to ground consistent at about 332 volts.Current was pretty much balanced at apx 24 amp with neutral of about 7 amps,neutral voltage apx 0.9 volt.Harmonics were slight at less than 1% total voltage distortion and current distortion of about 8%.Power factor was total of 0.67 lagging and phase A was 0.90 lagging,
phase B was about 0.90 lagging and phase C was 0.10 lagging apx.{!} Transformer feeds 24 1000watt metal halide
lights in six circuits.In theory everything should be close to balanced.Any ideas on why I have such a bizarre power factor? Rogue ballasts or lamps?Input appreciated.
Eldon

 

[unclebob]

Just to be sure: You did put all the current clamps correctly,
yes?

 

[Skogsgurra]

Also, did you make sure that the circuit configuration corresponds to the instrument connection? It is very easy to forget.

Gunnar Englund

http://www.gke.org

 

[waross]

How hot is the transformer. Modern transformers run very hot normally and people not familiar with them are often alarmed by what is actually normal operating temperature.
respectfully

 

[Eldon1955]

I greatly appreciate your replies folks.My current clamps are oriented with an arrow pointing in direction of load and instrument will flag incorrect installation at beginning of recording if incorrect.The recorder also has the circuit configuration in the set up program in this case 3phase four wire which was also correct but certainly noteworthy to double check these items.Instrument will also flag incorrect phase sequence as well.The point raised about how hot is too hot is also very valid,indeed it is hot but our new thermography tech is getting used to a new camera,he highlighted hot spots of inconsistence .Personally I feel it may well not be in danger of meltdown.The problem still remains of the bizarre power factor however I do have a Fluke 434 and think I will seek a "second opinion" from it.I greatly appreciate your input and will keep you posted on outcome.
Eldon