Being a large industrial electrical consumer at work we, like most others, have to pay a penalty per Kwh if our power factor falls below a certain point. Last year it was 80%, at the last Corporation Commisssion rate meeting they pushed for 90% but got 85% and may get 90% this year so it's something I've got to watch.
When we first moved into the building it was hovering in the low 80s, I managed to get that up to 98% during last winter by utilizing and moving around some of the PFC units that were left in the building when the previous tenent moved out but of course we weren't running the mainchiller that provides all the air conditioning. As we went into this summer it started dropping and at last billing it was down to 92%. Nothing has changed in our normal everyday load situation so that only left the chiller as upsetting the apple cart.
Today I finally got in a set of PFC caps I had to order from GE, one to put across each of the four compressors in the chiller. I went separate as the chiller will vary the number of compressors it runs according to the load it's seeing thus they only come into play if the contactor is active for any particular compressor.
While it will be another couple of months until I see the actual numbers stabilize on the billing I do know that the chiller, which was drawing 106.7A (480V 3 phase) under full load has now dropped to only pulling 100.6A - a 5.47% reduction. So long as we're still over 85% we'll get billed the same per Kwh at 85% or 100% PF, but the reduction in amperage draw can only mean that the motors are wasting less power due to true vs apparent. Also, by needing to pull less amperage through the wiring, the voltage drop along the lines will be less, my chiller compressors will see a bit higher voltage and will operate more efficently.
While there's no real payback involved for a common residential customer since very few are monitored for PF percentage it's going to make a small reduction in our electric bill and help protect me from penalties should they be granted the 90% number this year.
Point is when operating a large AC motor, even single phase, it pays to keep the reactive power losses to a minimum.
When we first moved into the building it was hovering in the low 80s, I managed to get that up to 98% during last winter by utilizing and moving around some of the PFC units that were left in the building when the previous tenent moved out but of course we weren't running the mainchiller that provides all the air conditioning. As we went into this summer it started dropping and at last billing it was down to 92%. Nothing has changed in our normal everyday load situation so that only left the chiller as upsetting the apple cart.
Today I finally got in a set of PFC caps I had to order from GE, one to put across each of the four compressors in the chiller. I went separate as the chiller will vary the number of compressors it runs according to the load it's seeing thus they only come into play if the contactor is active for any particular compressor.
While it will be another couple of months until I see the actual numbers stabilize on the billing I do know that the chiller, which was drawing 106.7A (480V 3 phase) under full load has now dropped to only pulling 100.6A - a 5.47% reduction. So long as we're still over 85% we'll get billed the same per Kwh at 85% or 100% PF, but the reduction in amperage draw can only mean that the motors are wasting less power due to true vs apparent. Also, by needing to pull less amperage through the wiring, the voltage drop along the lines will be less, my chiller compressors will see a bit higher voltage and will operate more efficently.
While there's no real payback involved for a common residential customer since very few are monitored for PF percentage it's going to make a small reduction in our electric bill and help protect me from penalties should they be granted the 90% number this year.
Point is when operating a large AC motor, even single phase, it pays to keep the reactive power losses to a minimum.