IR 2475 6 hp motor tripping 50 amp breaker

by Darren
(Evans co )

I have a IR 2475, 2 stage, 80 gal compressor.


I got this compressor on craigslist and it was in pieces for shipping. Everything seemed to be there but the control panel for the 3 phase motor.

It says 5hp 3ph motor on the tank but the motor and compressor are missing plates.

I first got a VFD to convert to 3ph and the first time it ran up to 150 psi and I shut it off there. The next day I did final wiring and got the pressure switch wired in but it wouldn't take off.

I blew down the pressure and it would run for 30 40 seconds then trip breaker.

I figured the VFD was under powered and sent it back.

At this point it was the same price to get a new 1ph motor.

I got a 6hp motor at tractor supply and got it wired up.

It was still doing the same thing it was at this point I went to a 50 amp breaker from the 30. Still doing it.

I troubleshot the pressure valve and with 100lbs there is no bleed off when the discharge line is unhooked.

I then took off the heads and looked at the valves, they looked fine. They were a little oily but nothing to serious. I cleaned everything up and put it back together. Same problem.

I have wire going to it that is at least 6 gauge and only 7' hard wired into breaker panel.

Have 240 at the motor.

The pressure seems to bleed off fine with the pressure switch.

I adjusted the belt a little and with it loose it squeals, it seems to do better but still trips the breaker.

It isn't always the breaker sometimes it is the thermal switch in the motor.

I changed the oil before running it with IR oil and a new filter. I put a quart in, the oil is right to the bottom of threads.

I am at a loss now.

Now I'm thinking it might be a 7.5 HP compressor and I am under powered to turn it over, getting worse with added pressure.

Comments for IR 2475 6 hp motor tripping 50 amp breaker

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Apr 05, 2016
Motor Pulley size?
by: Anonymous

What size is the motor pulley? If it is 8 inches or so you have a 7.5 HP compressor and you are overloading the 6 HP motor, but it should run till it burns up or trips the thermal overload if it has one. If it is 5 15/16 inches you have a 5 HP compressor and a 6 HP motor should run it fine. It should draw about 20 amps at 175 psi if it's a 5 HP and 30 amps at 175 if it is a 7.5 HP. A 50 amp breaker is marginal for starting a 30 amp compressor because of the starting in rush current. You can get breakers for some residential panels that are rated for starting motors but still protect the circuit at the proper current. (50 amps for a # 6 Cu wire.)

Mar 16, 2016
1hp motor
by: Darren

I think you miss read that. I now have a 6hp 1 phase motor. Not a 1hp motor.

Mar 15, 2016
Tripping
by: Doug in s.d.ca

Darren:

According to Grainger that is a 5 HP @ 1040 RPM minimum. (google IR 2475 pump)

So, you'd have to use sheaves that would give you 200 RPM or so to turn it with the 1 horse motor.

Your call...

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Ingersoll Rand 2475 will blow the breaker on first start up

by Ronnie
(Ohio)

Will blow the breaker but only on first start up in the morning then is fine the rest of the day.

Ingersoll 2475 electric 7.5 hp I have a auto repair shop and this unit is about 7 years old.

When weather gets colder the compressor will surge up and down trying to start in the mornings and sometimes blows the breaker but after that it runs fine the rest of the day.

We have been leaving the shut off valve open at night to bleed pressure off and this has helped but it will still struggle.

The shop temp is at 70 and the start cap has been checked.

Comments for Ingersoll Rand 2475 will blow the breaker on first start up

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Dec 23, 2015
breaker
by: Doug in s.d.ca

Good you checked the start cap.

Your description actually sounds like a run cap or centrifugal switch problem.

Does the shop stay at 70 all night?

Dec 23, 2015
Breaker type
by: Ronnie

I live in the US not sure on breaker type. I don't understand why it only does this on the first start up in the morning then is fine the rest of the day, it probably cycles on and off through the day about 30 times and but only has the issue in the mornings during colder months, I am afraid it's going to burn the motor up if I don't find a solution.

Dec 23, 2015
Breaker type
by: Carl

Hi,
Which type of breaker are you using?

I'm not sure which country you live in but here in the UK, a normal type breaker (B-type) is sometimes OK, but can trip when under pressure so should be replaced with a C or D type.

These types of breaker have a time delay before tripping so it can take the extra load when the compressor is under pressure.

If you already have this type then it may have just weakened as it has tripped so many times.

Hope this helps

Carl

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2475N7.5 breaker trips after 5 seconds

by Scott L.
(Illinois)

Hi,

I just installed a "Brand New" Ingersoll Rand Compressor.

Single Phase / 230v. 60Hz.
Model #: 2475N7.5

It's a 7.5 hp. and I put it on a 2-Pole 50amp. breaker (22,000 AIC) with #6 awg. wire.

When the motor kicks on (Briefly for 5 secs.) before the breaker trips, the voltage drops to between 215 to 208.

The building only has single phase to it.

The voltage drops even when bypassing ComEd's meter.

I am at a loss.

Your thoughts would be appreciated.

Thank you,
Scott L.

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Sep 04, 2015
Ingersoll Rand 2475N7.5
by: Scott L.

Hi Doug,
The motor spins as it normally would on start-up.
I tested voltage at the compressor, panel and meter.
It is an old neighborhood and it is the last building the transformer feeds. I will definitely let you know.
Thank you for your input.
Much appreciated,
Scott L.

Sep 03, 2015
blows breaker
by: Doug in s.d.ca

Sounds like you've got your part wired appropriately.

What's happening during the five seconds? Does the motor just hum or does it (sorta, actually) run during that time?

Where are you measuring the voltage? At the pump or at the breaker box? Is the breaker on the main service panel or a sub-panel?

Are you in an older neighborhood? Residential or commercial?

I've seen low voltage due to overloaded service transformers. Did you check with Comed before installation? Depending on circumstances, and if it is their equipment, they may upgrade. Possibly only for a price, as in you pay for it.

Let us know,,,

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