Tranformer overheating due to harmonics from rectifier

[louie]

I'm considering a 6 pulse recitifer which is used to control a dc motor. A delta-wye transformer is located before this rectifer and is being subjected to excessive heating. I am interesting in seeing the Irms^2*R (heat) that is being produced, due to the harmonics of this rectifier. I'd like to determine the relationship between heat and the firing angle of the scr's.

Can anyone give me a hand accomplishing this ?

Thanks,

Louie

 

[charlie tuna]

Re: Tranformer overheating due to harmonics from rectifier

purchase or rent a data logger capable of recording this "harmonic" problem and install it on the secondary side of the transformer --- download the results and find out if the heat is actually caused by load or "harmonics"????????

 

[jcormack]

Re: Tranformer overheating due to harmonics from rectifier

Is the Wye Solidly Grounded ? If so, you could entertain using a resistance grounded Wye - that would reduce some of the Harmonic currents that flow in the neutral - of course the external resistor would have no effect on circulating currents within the trans itself. On 12-pulse drives where you have both Delta & Wye secondaries, we use high resitance grounding with a "tee" arrangement to help reduce inter-winding current flow.