PDA

View Full Version : What is the code on the max voltage imbalance for running a three phase motor



bwd111
04-30-2013, 09:36 PM
I cant find the % anywhere. I was thinking it was 5% but not sure

ReferYankee
04-30-2013, 09:54 PM
3% back when I was in school, 00-04, I think 4% max now is standard

Sent from my SCH-I500 using Tapatalk 2

bwd111
04-30-2013, 10:30 PM
3% back when I was in school, 00-04, I think 4% max now is standard

Sent from my SCH-I500 using Tapatalk 2

How about the starting current drawn by a single phase motor how much can that exceed running current Is it 2 to 3 times or 7 to 9

second opinion
04-30-2013, 10:33 PM
I cant find the % anywhere. I was thinking it was 5% but not sure

Not a code but a NEMA standard 2%

BigDanB
04-30-2013, 11:36 PM
2% max voltage imbalance and I believe inrush is 5-8 times the normal running amps

Core_d
05-01-2013, 06:41 AM
Here is another good thread on the subject. http://hvac-talk.com/vbb/showthread.php?1274321-acceptable-amperage-imbalance&p=15366761

eddiegoodfellar
05-11-2013, 12:18 AM
They are teaching us 2% voltage and 10% amperage in school as good practice ( not sure about code )

Core_d
05-11-2013, 04:35 PM
They are teaching us 2% voltage and 10% amperage in school as good practice ( not sure about code )

You have an NCCER curriculum at your school?

WyrTwister
06-20-2013, 12:04 AM
I cant find the % anywhere. I was thinking it was 5% but not sure

Never really thought about it . You kind of lived with what the power company gave you . Unless it was TOO bad & the power company found something was defective .

Best I remember , you can get a pretty large imbalance on open delta 3 phase 240 VAC ?

Do some of the rural power companies still use open delta ?

I have also seen 240 VAC run 255 VAC . 480 VAC at 500 VAC fairly common .

God bless
Wyr

deerwhistle
07-07-2013, 05:59 PM
In Canada the maximum deviation from averaged voltage in 3 phase circuits is 2%. Not sure what single phase supply % is allowed as there is no deviation phase to phase or phase to ground.