Great white
Well-known member
- Joined
- Nov 6, 2009
- Messages
- 175
Got tired of the cheap direct drive unit I had (IE: too loud) and have been gathering up parts to assemble a "better" one.
Compressor is a 2 cyl, v pump. Single stage. Calls for 2 hp. Just like the ones you can buy at Harbour freight.
Tank is the old one, which is about a 26 gallon vertical. About all I really have room for and my use is "light". Just home garage type stuff. Air tools, impact, etc. The pump is rated for enough cfm@psi for my modest uses. I don't use a lot of air hogs. Plasma is about the worst draw and that used to work fine on the old, lower cfm rated, direct drive pump.
I reused the pressure switch/unloader assembly (which I think is my issue, more to follow).
Motor is a 3hp. Single phase, 220, 15 amp. It's a Vevor, the "compressor rated" one. Runs fine no load. Smooth and quiet. Turns over smoothly by hand without scratching or other noise.
It's on a dedicated 15 Amp 220 service. I just used a dryer plug and dryer cord (only using line 1 and line 2). Dryer receptacle was a choice of convenience as it was easiest to find locally. Qualified electrician installed the receptacle. He was shown the motor and it's requirements and asked to size appropriately. It's about 2 feet from the main panel and on it's own breakers (obviously).
Wire from the pressure switch to the motor "in" is at least the same size as the wiring inside the motor at the connections.
Pulley's are calculated to run a shade over 1100 rpm, pump is rated for 1300 rpm max.
Everything seems like it should work. But when I turn it on, sometimes the motor will rapidly cycle. You can hear the switch turning on and off rapidly. This causes me to flip the switch "OFF" almost immediately as that's just not good for the motor.
Leaving the tank bleed open will allow the motor and pump to run without issue. Close the bleed and it will build pressure to about 50 psi and then the motor loads down and stops.
Belt is not slipping.
I put an amp clamp on the motor wiring and it draws 1 to 5 amps when running up to 50 psi. When it hits roughly 50 psi the amp draw goes up rapidly to 20-25 amps and you can hear everything load down quickly. I only know it goes that high because I couldn't get to the off switch fast enough. Tried that twice and same result so I didn't try anymore times. Don't want to overheat/fry to the motor. Motor still runs fine in a no/light load condition.
Can't be the unloader, right? Unless my understanding is wrong, the unloader only comes into play on shut down/startup. So it shouldn't be why the pump is loading up and stalling the motor, right?
Tank check valve seems to hold once the pump shuts down.
Now the pressure switch, which I think might be my (self inflicted) problem.
It was originally used on the 110v motor/pump But the chart inside the cover of the pressure switch gives a 220 single phase rating which is 12amps. The new motor is a 15 amp max draw, so I thought it might be ok with it beng a 12amp switch.
Did I shoot myself in the foot with reusing the pressure switch? Can this be why the amp draw goes high when the pump loads past 50 psi? IE: too much current draw through the switch contacts, increases resistance, increases draw, etc?
The pressure switch did wok fine on the old 110v motor, so I'm thinking it's the draw, not so much the pressure switch itself is gone duff internally.
I've already got a 220v 26amp pressure switch on order, but I'd like to try and understand where I went wrong before trying with the new switch assembly.
Thanks
Compressor is a 2 cyl, v pump. Single stage. Calls for 2 hp. Just like the ones you can buy at Harbour freight.
Tank is the old one, which is about a 26 gallon vertical. About all I really have room for and my use is "light". Just home garage type stuff. Air tools, impact, etc. The pump is rated for enough cfm@psi for my modest uses. I don't use a lot of air hogs. Plasma is about the worst draw and that used to work fine on the old, lower cfm rated, direct drive pump.
I reused the pressure switch/unloader assembly (which I think is my issue, more to follow).
Motor is a 3hp. Single phase, 220, 15 amp. It's a Vevor, the "compressor rated" one. Runs fine no load. Smooth and quiet. Turns over smoothly by hand without scratching or other noise.
It's on a dedicated 15 Amp 220 service. I just used a dryer plug and dryer cord (only using line 1 and line 2). Dryer receptacle was a choice of convenience as it was easiest to find locally. Qualified electrician installed the receptacle. He was shown the motor and it's requirements and asked to size appropriately. It's about 2 feet from the main panel and on it's own breakers (obviously).
Wire from the pressure switch to the motor "in" is at least the same size as the wiring inside the motor at the connections.
Pulley's are calculated to run a shade over 1100 rpm, pump is rated for 1300 rpm max.
Everything seems like it should work. But when I turn it on, sometimes the motor will rapidly cycle. You can hear the switch turning on and off rapidly. This causes me to flip the switch "OFF" almost immediately as that's just not good for the motor.
Leaving the tank bleed open will allow the motor and pump to run without issue. Close the bleed and it will build pressure to about 50 psi and then the motor loads down and stops.
Belt is not slipping.
I put an amp clamp on the motor wiring and it draws 1 to 5 amps when running up to 50 psi. When it hits roughly 50 psi the amp draw goes up rapidly to 20-25 amps and you can hear everything load down quickly. I only know it goes that high because I couldn't get to the off switch fast enough. Tried that twice and same result so I didn't try anymore times. Don't want to overheat/fry to the motor. Motor still runs fine in a no/light load condition.
Can't be the unloader, right? Unless my understanding is wrong, the unloader only comes into play on shut down/startup. So it shouldn't be why the pump is loading up and stalling the motor, right?
Tank check valve seems to hold once the pump shuts down.
Now the pressure switch, which I think might be my (self inflicted) problem.
It was originally used on the 110v motor/pump But the chart inside the cover of the pressure switch gives a 220 single phase rating which is 12amps. The new motor is a 15 amp max draw, so I thought it might be ok with it beng a 12amp switch.
Did I shoot myself in the foot with reusing the pressure switch? Can this be why the amp draw goes high when the pump loads past 50 psi? IE: too much current draw through the switch contacts, increases resistance, increases draw, etc?
The pressure switch did wok fine on the old 110v motor, so I'm thinking it's the draw, not so much the pressure switch itself is gone duff internally.
I've already got a 220v 26amp pressure switch on order, but I'd like to try and understand where I went wrong before trying with the new switch assembly.
Thanks
