3 phase efficiencies

Old 02-10-15, 08:42 AM
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3 phase efficiencies

I realize 3P motors are more efficient and can result in lower electrical bills, but do 3 phase efficiencies apply to any other loads?

More specifically if I have three single phase resistance heaters that are connected to a 3p service using two each of the 3 phases(A & B to one heater and B & C to another and A & C to the third) is there any energy savings or is it simply the combined wattage's of each heater that goes into the billing?

Or another way of asking the question is how important is it to keep loads balanced on a 3 phase service as it relates to cost. Thanks
Old 02-10-15, 08:51 AM
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Resistance heaters are 100% efficient (watts in electric = watts out heat) no matter the source, so it really doesn't matter. However with a 3P service (regardless of the type of loads) it is important to keep the phases reasonably balanced to keep the transformer operating efficiently without overheating or shifting phase. This is probably more of a power quality issue than one of cost, but poor power quality does have an associated indirect cost.

As far as various other loads (light ballasts, computers, etc), the design of the machine is a lot more important than the phasing of the source. If it's designed to be efficient on that source, it will be.

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