- Thread starter Daz2012
- Start date
Oh its been used all right 1945 vintage.
Have a look at wyns
http://www.mig-welding.co.uk/forum/showthread.php?t=12499
Right we're getting somewhere now.
Had a sparky out today.The motor is rated at 12amps,the thermal overload at 18 but it's actually pulling over 20amps under load.
Looks like the increased efficiency of the pump is straining the motor.I'm going to have to look out for a more powerful motor and probably go 3 phase.
Had a sparky out today.The motor is rated at 12amps,the thermal overload at 18 but it's actually pulling over 20amps under load.
Looks like the increased efficiency of the pump is straining the motor.I'm going to have to look out for a more powerful motor and probably go 3 phase.
What rpm is the Kapak motor.
Phase makes no difference, power is power. No caps to degrade but it will still pull too many amps.
shenion
Tool Pack Rat
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- 7,586
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- Stone Mountain, GA USA
At 1400 RPM you would get half the CFM unless you changed to a larger pulley.
I would still replace the cap to see if it improves the current efficiency. You might get a bit more RPM (excessive slip would cause a high current.)
Another option it to put a bit smaller pulley on the existing motor. That would reduce the load.
I would still replace the cap to see if it improves the current efficiency. You might get a bit more RPM (excessive slip would cause a high current.)
Another option it to put a bit smaller pulley on the existing motor. That would reduce the load.
There is no way around the power requirement to achieve the rated CFM of the pump. It's like a car, to reach a given speed requires a certain power, changing the gearing without having the power means the car either goes slower at higher revs, or it reduces the the revs at the speed the power provided allows it to reach.
Remember, power = torque x RPM
As you mentioned, now the pump is working at full capability, it requires more power.
Remember, power = torque x RPM
As you mentioned, now the pump is working at full capability, it requires more power.
If you are getting the motor for very little money and you have the 3phase supply already for it then get yourself a 7" double A vee pulley, two belts if need be and it will be like mine.
The receiver on mine is 500 x 1220, making it 234 liters by my calculations. It fills up from 0 to 10bar in 6mins.
going by this calculator http://www.cambscompressors.co.uk/UserFiles/File/Calculating Air Compressor Flow Rates.pdf
Which means mine gives me 13.77 CFM fad. if this will do you then stick the 3hp on. if its not enough air then you need a bigger motor Simple isn't it.
The receiver on mine is 500 x 1220, making it 234 liters by my calculations. It fills up from 0 to 10bar in 6mins.
going by this calculator http://www.cambscompressors.co.uk/UserFiles/File/Calculating Air Compressor Flow Rates.pdf
Which means mine gives me 13.77 CFM fad. if this will do you then stick the 3hp on. if its not enough air then you need a bigger motor Simple isn't it.
It would be that simple if I was getting conflicting advice lol.
My current set up gives me enough air....if it wasn't for the tripping (incidentally one day it's fine then next it's tripping constantly )..... and I was lead to believe by going 3-phase with the same hp but half the rpm but an increase in torque the motor wouldn't have to work so hard so would run cooler anyway.
All I want is a compressor that doesn't trip out,I don't need more cfm
My current set up gives me enough air....if it wasn't for the tripping (incidentally one day it's fine then next it's tripping constantly )..... and I was lead to believe by going 3-phase with the same hp but half the rpm but an increase in torque the motor wouldn't have to work so hard so would run cooler anyway.
All I want is a compressor that doesn't trip out,I don't need more cfm
shenion
Tool Pack Rat
- Messages
- 7,586
- Location
- Stone Mountain, GA USA
A motor with half the RPM but the same HP will have twice the torque. However, as you will need a pulley twice as big, the torque load will be double.
Remember HP = RPM * torque.
It is just your compressor seems to pull over 3HP with the current pulley ratio. Either reduce the ratio or increase the motor HP.
Replacing the run cap would be cheap. IT may help as if it is old it probably has less capacitance that rated.
A 3-phase motor may work a bit better as they tend to be better rated. You would have to change the pressure switch with a 3-phase contactor.
Remember HP = RPM * torque.
It is just your compressor seems to pull over 3HP with the current pulley ratio. Either reduce the ratio or increase the motor HP.
Replacing the run cap would be cheap. IT may help as if it is old it probably has less capacitance that rated.
A 3-phase motor may work a bit better as they tend to be better rated. You would have to change the pressure switch with a 3-phase contactor.
Daz, you have being using a motor rated 12amps on an overload set at 18 amps for how long ?. the thing here is none of us can know what condition your motor is in now, if you could have it checked out at a rewinds place or a sparky thats used to working on motors could check the resistance and the capacitor for you then you might have more options as how to proceed. personally I wouldn't have tried to run a big old compressor as the T30 on a two pole motor but in saying that you have had quite a few years out of it so get it properly checked out first so you know exactly where you stand.
