Hi guys the motor on my compressor finally gave up, it was a 3hp on 200 ltr tank which had originally a 3hp 3phase motor it was swapped over to a 3hp 240v motor, now this one has failed im not sure if I can use a smaller size motor of around 2hp with a speed of 1500 rpm or 2800 can anyone help I am getting the other motor looked at but it will be a spare due to the problems I had with it prior.
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rtbcomp
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If you fit a smaller motor with the same pullies you won't be able to reach the previous maximum pressure.
Again with a smaller motor reducing the motor pulley size (or preferably increasing the pump pulley size) you will not get the same cfm.
If you replace a 1400 rpm motor with a 2800 rpm motor of the same power you will only get half the torque, with a corresponding loss of maximum pressure.
In all cases you have to make sure you don't overspeed the pump.
Again with a smaller motor reducing the motor pulley size (or preferably increasing the pump pulley size) you will not get the same cfm.
If you replace a 1400 rpm motor with a 2800 rpm motor of the same power you will only get half the torque, with a corresponding loss of maximum pressure.
In all cases you have to make sure you don't overspeed the pump.
ok so if I replace it with a motor that runs at 2800 what should the motor size be, should I replace with a 3 hp or could I use a 2hp running at 2800 or should i just go back to 3phase which is what it originally was.
I think the pump was running at 2800 prior in 3phase
I think the pump was running at 2800 prior in 3phase
brightspark
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if it had a 3hp motor fitted at either 1400rpm or2800 replace it like for like even if its 3 phase or single . less than £100 quid for a 3hp motor
rtbcomp
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I'm assuming it's a belt driven compressor.
Compressors usually use 1400 rpm motors because of their greater torque for the power. I'd be inclined to fit a 3hp single phase 1400 rpm, but if you've got 3 phase go for 1400 rpm 3 hp 3 phase, a used one will be cheaper than single phase (less demand for them).
Divide the diameter of the motor pulley by the diameter of the pump pulley to get the ratio. Multiply this ratio (which will be less than 1) by the motor speed to get the pump speed, this will most likely be in the range 500 - 1000 rpm.
Compressors usually use 1400 rpm motors because of their greater torque for the power. I'd be inclined to fit a 3hp single phase 1400 rpm, but if you've got 3 phase go for 1400 rpm 3 hp 3 phase, a used one will be cheaper than single phase (less demand for them).
Divide the diameter of the motor pulley by the diameter of the pump pulley to get the ratio. Multiply this ratio (which will be less than 1) by the motor speed to get the pump speed, this will most likely be in the range 500 - 1000 rpm.
octo0072000
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motor
sounds like it's de rated already from 3hp 3 phase to 3hp single phase could why the new motor quit so soon pump too big for motor
sounds like it's de rated already from 3hp 3 phase to 3hp single phase could why the new motor quit so soon pump too big for motor
octo0072000
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might be wrong but 3hp 3 phase needs 5hp single phase
im sure so of the sparkys will be along shortly
im sure so of the sparkys will be along shortly
brightspark
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might be wrong but 3hp 3 phase needs 5hp single phase
3 phase is more eficcient and has better starting characteristics {more torque} than single phase but 3hp is 3hp no matter whatsorry should really of pointed out that the pump is a v twin and looking on the clarke site they sold the twin compressor with 2hp- motor,I got it from a saw mill and it had a 3hp 3phase motor on this was broken so i put a 3hp single phase on thinking thats what it should have
I was going to swap the pump at some point so maybe worth buying both as machine mart do a v twin clarke pump for around £137 and the 2hp motor is around £100 although ebay do have 1 for under £90.although the pump is working fine so it may be swapped out a lot later
I was going to swap the pump at some point so maybe worth buying both as machine mart do a v twin clarke pump for around £137 and the 2hp motor is around £100 although ebay do have 1 for under £90.although the pump is working fine so it may be swapped out a lot later 