1 hp air compressor has a 197 amp spike at start

[gsonger32]

I have a 240v 37.4 amp compressor . 1 hp
the power run is 200 ft. I have 2 #6 feeding the compressor . THere are 2 compersors on 2 240 breaker
when the compressor starts the amps spike to 197 amps for abpout 5 sec ,Then when its running it goes to 35 amps.
When it was first installed there was only one cert. running both compressors, later it started to trip breakers, then a second breaker has be added it trips when both compressor start,
please help.
Thanks Gregg
it is being feed with 2 2 pull 240 50 amp breakers
the feed run is 200 ft in a 3/4 comduit with 2 # 6 and 1 #10 grd
each compreossor has its own home run with a 50 amp 2 pull breaker
i hope that helps
Gregg

 

[royal]

Are you saying that you have the two compressors being fed by two breakers sharing the same two number six wires?
What type of meter are you using to check the amperage draw?
How old is this compressor?
Is this a refrigeration or air compressor?
Is the second compressor the same size as the first?
What size of breakers are you using?
Not enough information at this time to diagnose your problem.

Tim

 

[pierre]

Check the label on the compressor, as you may have too small a circuit breaker supplying the unit.
A/C equipment labeling is provided by the manufacturer with all calculations performed by them. It will tell you what size overcurrent device to install, you may be surprised.

 

[peter d]

High starting current is not abnormal for a motor, but it shouldn't last 5 seconds. This sounds like a problem with the motor and/or compressor system. It might be trying to overcome some built up pressure in the system. Check the pneumatics.

 

[catchtwentytwo]

High starting current is not abnormal for a motor, but it shouldn't last 5 seconds. This sounds like a problem with the motor and/or compressor system. It might be trying to overcome some built up pressure in the system. Check the pneumatics.

I agree, there usually is an "unloader" that helps with the back-pressure during starts.

 

[infinity]

How do you have a 1 HP compressor @ 240 volts with a 35 amp FLC?

 

[eric stromberg]

With what little information is here, let me take a stab at it.

Table 430.248 shows the following:
5 hp @ 230V = 28 Amps
7.5 hp @ 230V = 40 Amps.

So, let's assume this is a 7.5 Hp motor drawing 40 Amps (Nameplate of 37 something).

The wire size should be 125% FLA, which = 50 Amps. Assuming 75degC terminations, you could do this with 8AWG conductors, depending on distance.

It sounds like you are using inverse time breakers for the OCPD. 430.52 shows these to be 250% of FLA. 40*2.5 = 100 Amps. So it seems like you should be using a 100 Amp breaker for this.

Does this (do these) motor(s) have internal overloads?

Eric