4160 Motor Efficiency
4160 Motor Efficiency
(OP)
I am trying to figure out the heat load in a municipal pumping station. The dominating load is three 4160 volt motors, dating from the mid 80's, driving the pumps. I have been trying to determine the standard or baseline efficiencies for motors of this type from this time and can't find diddly squat. Does anyone have information on what the standard or baseline efficiency for these motors might have been? (250 HP, 350 HP, and 1250 HP if it matters) Is there a resource out their that I could use for similar projects in the future?
Thanks in advance
Thanks in advance






RE: 4160 Motor Efficiency
But since that is 80% eff of the connected load, that SWAG is still relatively meaningless without knowing the actual loading. So to do that, you will need measurement anyway. If that's the case, just determine the flow rate, head etc. to determine the necessary work kW requirement, then measure the input kW and the difference is going to almost all be heat rejected into the room one way or another by the motor (a little bit in cables and windage does not translate to rejection into the room, but it's relatively insignificant).
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RE: 4160 Motor Efficiency
The best bet is to contact the motor manufacturer.
David Castor
www.cvoes.com
RE: 4160 Motor Efficiency
Bill
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"Why not the best?"
Jimmy Carter
RE: 4160 Motor Efficiency
RE: 4160 Motor Efficiency
RE: 4160 Motor Efficiency
RE: 4160 Motor Efficiency
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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RE: 4160 Motor Efficiency
I am consulting on a larger ventilation/cooling problem they have (It is more than these motors although as I stated above they are a big part of it), and based on my previous experience and some of the info from this thread I am defaulting to the motore being 80% efficient at 100% load and not using the higher efficiency numbers. However, on a 1250HP motor the difference between 80% and 90% efficiency is substantial. A 1250 HP motor that is 80% efficient and running at 100% load puts out just over 795 MBH of heat. The same motor at 90% efficieny puts out less than half at just over 353 MBH (using ASHRAE motor heat calcs). You are definitely right that undersizing can bury you, but in this case oversizing can bury you as well. The difference in motor efficiency in this situation is the difference between ~37,000 CFM of ventilation infrastructure and ~74,000 CFM of ventilation infrastructure, assuming you maintain a 10F temperature rise (outside air is 90F and you don't want the space above 100F).
RE: 4160 Motor Efficiency
"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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RE: 4160 Motor Efficiency
I don't recall seeing any large motors where the efficiency changed by more than a few percentage from 50% to 100% load.
Sounds like more investigation is necessary. I'm not surprized. I had an idea you'd find that being overly conservative would also have consequences but didn't bother posting it last time (it wasn't the question being asked).
RE: 4160 Motor Efficiency
Sorry, I have at the moment nothing to contribute to your original question.. has been covered well.
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RE: 4160 Motor Efficiency
Hermetic chiller motor 600hp 4kv, 3550rpm.
Efficiency at 50%/75%/100%: 0.956 / 0.952 / 0.938
Vertical Motor 1000hp, 4kv ~3600rpm
Efficiency at 50%/75%/100%: 0.943 / 0.949 / 0.949
Vertical Motor 400hp 4kv, 1800rpm
Efficiency at 50%/75%/100%: 0.92.8 / 0.93.4 / 0.931
Horizontal Motor 800hp, 4kv, 3561 RPM
Efficiency at 50%/75%/100%: 0.940 / 0.948 / 0.949
Horizontal Motor 600hp, 4kv, ~3600 RPM
Efficiency at 50%/75%/100%: 0.927 / 0.937 / 0.934
Horizontal Motor 800hp 4kv ~1800rpm
Efficiency at 50%/75%/100%: 0.933 / 0.927/Unk (not recorded at full load).
Regarding copper magnet wire conductivity, NEMA Standard MW1000 (Magnet Wire) 1981 version said the same thing as NEMA Standard MW1000 2010 version says: 100% of IACS as a minimum. I don't think there is much variation in that except a few very special applications that might go higher. There are plenty of sources of efficiency variation among older motors, but as far as I know the conductivity of stator winding copper material is not one of them.
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RE: 4160 Motor Efficiency
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