Turbocor Harmonic Filters

[DaveK52]

We've recently installed 3 100T Turbocor compreesors as a retrofit to one of our chilled water system. The manufacturer insisted that we install Harmonic Filters just upstream of the units. Checking power quality and power factors, we found that the PF before the filters was 0.8 which seems somewhat normal. After the filters, the PF reads 1.27.
Question is, Has anyone else had this problem/situation? Will this leading Power Factor have any effect on the VFD's in the units? Are the Harmonic filters really needed?

 

[ScottyUK]

DaveK,

I think you have an instrumentation problem. A power factor greater than unity is a nonsense value. Power factor ranges between 0 leading (pure capacitive) through unity (pure resistive) to 0 lagging (pure inductive). I agree that a 0.8 PF seems fairly reasonable, but there are other factors such as harmonics which may require the filters to meet operational or legislative requirements, plus the question over the validity of the PF measurement based on the data posted.

It is interesting that the manufacturer insisted on filters. Was that after a site survey and collection of electrical data for your site? Either they are pretty clued up and have a very pro-active applications engineer, or they took the chance to sell some additional CYA equipment. Is the filter an active or passive type? Active ones have some physical similarity to a variable speed drive in appearance if you're unsure.


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If we learn from our mistakes I'm getting a great education!

 

[DaveK52]

Scotty,

Thanks for the reply. I thought that PF could be no greater than 1.0 but wasn't totally sure. The readings were taken by others and I wasn't present. I'll have to see how the readings were taken.