I have a air compressor that runs on 480 volts three phace.?

Question

one leg of power reads 37.8 amps. second leg reads 39.2 amps third leg reads 37.9 amps.How can i figure how many kilowatts this compressor is using in a hour ,a day,a year. thank you.

Answer 1

Almost 32KWh
Voltage is 480V. It means that voltage between 1 phase and ground is 277V (480/1,73).
Power=voltageXcurrent
Power on phase 1 = 10487W
Power on phase 2 = 10854W
Power on phase 3 = 10498W
Add the 3 power and u get about 32KWh
U can apply the Blondel law for three phase power measurement to get an accurate reading. Get three Watt-meters and connect the first between phase 1 and ground, the second between phase 2 and ground and the third between phase 3 and ground. Sum up all the 3 readings to get the total power.

Here is a site that shows u how to apply the Blondel law, the example depicted uses 4 watt-meters, u can use the 3 wattmeters not 4.
http://www.actrus.ro/biblioteca/cursuri/electro/teodoru0/c3243.html

Answer 2

A couple of answers are fair and more than likely in the ball park but still incorrect.
Before I go any further, a WORD OF CAUTION. # PHASE ELECTRICITY WILL KILL YOU IN A HEART BEAT. I saw a man get hit by it and it blew his shoes and one foot off. Please be very care with it.
With that said, The legs reads 37.8, 39.2. and 37.9 amps, but voltage is never exactly the same everywhere. You will have to check the indivual voltage for each leg.
The low legs may be as low as 108 to 110 volts or as high as 124 to 125 volts and they may not even be the same. Then you have the high leg which is supposed to be 277 volts but will also vary.
Check the amps of each leg and the the voltage of each leg and then multiply them and you get the watts for each leg and then add them all 3 up. That gives you the total watts.
A kilowatt Hr is 1,000 watts used for one hour, so devide the number by 1,000 and then figure how many hours it actually runs.
A compressor kicks on and off quite often when you are useing them or if you have any leaks in the lines, fittings, or hoses.
The best way to figure it out would be to use a meter to get the hours it runs per month, but you could use a stop watch for a day or two to add up the actual running time.
According to what you are doing, it may only run less than a hour a day or if you have leaks and useing it steady, it may run a lot more.
Every bit of that is a factor in how much electricity it uses.

Answer 3

amps + amps + amps x voltage = watts, watts / 1000 = kilowatts

37.8 + 39.2 + 37.9 X 480 = 55776, 55776/1000 = 55.76 per hr

Answer 4

It uses a whole crap load. Don't leave that on by accedent while your away on vacation.