The Stovebolt Site Forums The Shop Area The Tool Chest Getting compressor working.

Got the new hobo freight on spaced and set up. The motor turns it just fine when under 100lbs of pressure. At about 110 it pops the breaker. Once reset it can't spin up unless psi is dropped.

The pump head says 5hp. Motor tag is 5hp 15 amps. I have it to a 15A double pole breaker.

The only difference is this pump head is two piston.

Does my motor need attention, do I need a bigger breaker, or a smaller pully on the motor cause of two pistons vs one?

The smaller pulley on the motor would help as long as it didn't cause belt slip. But I'd start by address the electricals.

A circuit breaker should be rated higher than the running load. Check the "starting load" of the motor, and then size the breaker and wiring to match.

10 gauge wire should do if the run isn't too long..

15 amps seems too lite for a 5 horse motor, the nameplate should give you a FLA or LRA rating, full load amps is probably near that 110 psi, locked rotor amps is at start-up. you could swap it over to another 2 pole breaker to test the theory. While you are in the breaker panel, tighten every screw that you can find but BE CAREFULL!

Tag on motor says 15A. Wire gauge is 10 as this originally was a 30A 110 rv plug.

More I think about it I am leaning to a smaller motor pully, but swapping the breakers out is easy. I have a 40A in the panel. I am comfortable working inside a live panel.

Does your compressor system have an unloader valve? It unloads the pressure in the cylinder head so the compressor isn’t trying to overcome high pressure on restart. Here is a site that explains it’s function.

Does the compressor have an unloader that allows the motor to spin up to speed before it starts compressing? If not, one should be installed. Are you running 120 or 240 volts? A 5 HP motor on 120 is sending a boy to do a man's job.
Jerry

It's 240 circuit.

The spare one i got for nothing just for a flywheel had a 3hp 120 motor on it which was advertised for 175 lbs.

It's not just the pressure capability that dictates what HP is needed, but the displacement of the compressor. So your spare with a 3 hp motor doesn't mean anything. I'll bet it's quite a bit smaller physically than the one you're planning on using.

You could run the whole thing with a 1/2 HP motor if you had a big enough pulley on the compressor. It might take a week of Tuesdays to pump the tank all the way up though.

Well there is hp and then there is china hp
But I tend to have 20 amp 220 plugs or even 30 amp plugs
Size the breaker to the wire, 20 amp should help
Your pressure switch will have a max and a start pressure.
It won’t start again till pressure is down to the min.

Evening all. I swapped breakers and the motor simply ran put of steam and would not restart when the psi switch closed.

So I brought the motor to a rebuild shop nest me. They tested it and found it making 5hp at 15 amps. Said it's doing everything it was designed to do.

They sold me a smaller and adjustable sheath pully. Installed in the tallest setting which was much smaller than original.

Now belt is too long and not enough adjustment.

Two trips to the parts house and got one to fit. Now it runs to full psi 155 without shutting down, and restarts at 120.

Looks like the two piston head unit makes a big difference.