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sikeston34m · 11.15.2007, 12:27 AM

Wow ZPB. You're a wizard with words.

You are correct.

At work, we have discussed installing VFD's on the compressors to increase overall effiency. They are Frick Twin Screws that are variable compression ratio. We have 1300 Compressor Horsepower on site contained in 4 units. The smallest being a 250 Horse Booster compressor and the largest being a 450 Horse High stage compressor.

We hold a 5 million cubic foot freezer at 20 below zero. Frozen Distributor mainly focusing on Ice Cream. We can hold 22,000 pallets of ice cream.

Simple rule of how they vary compression ratio, the longer the refrigerant is held in the screws, the tighter it's compressed before being released into the discharge port. Slide Stop setting is what it's called. They unload by blowing compressed vapor back into the suction header. This really hurts effiency.

VFD's would allow capacity to be controlled by speeding up and slowing down the drive motor, instead of loading/unloading the compressor head to maintain a given suction pressure range.

VFD's also greatly improve magnetic harmonics, thus improving the overall power factor. They have built in power factor correction.

I've always wondered how the power company can tell how efficiently you are using their power? But they can and do.

	(#9)
sikeston34m RC-Monster Brushless Offline Posts: 2,085 Join Date: Sep 2007	11.15.2007, 12:27 AM Wow ZPB. You're a wizard with words. You are correct. At work, we have discussed installing VFD's on the compressors to increase overall effiency. They are Frick Twin Screws that are variable compression ratio. We have 1300 Compressor Horsepower on site contained in 4 units. The smallest being a 250 Horse Booster compressor and the largest being a 450 Horse High stage compressor. We hold a 5 million cubic foot freezer at 20 below zero. Frozen Distributor mainly focusing on Ice Cream. We can hold 22,000 pallets of ice cream. Simple rule of how they vary compression ratio, the longer the refrigerant is held in the screws, the tighter it's compressed before being released into the discharge port. Slide Stop setting is what it's called. They unload by blowing compressed vapor back into the suction header. This really hurts effiency. VFD's would allow capacity to be controlled by speeding up and slowing down the drive motor, instead of loading/unloading the compressor head to maintain a given suction pressure range. VFD's also greatly improve magnetic harmonics, thus improving the overall power factor. They have built in power factor correction. I've always wondered how the power company can tell how efficiently you are using their power? But they can and do.