2hp 7amp 220 volt

[Dave Right]

I had an OEM 2 hp 10 amp 220 volts motor go bad and was replaced
thru warranty but received a 2hp 7 amp 220 volt that seems like it does
not have the power that the original one did but could be me.
I was thinking that normally a 220 volt motor with 7amp capacity would be
a 1 1/2 hp not a 2 hp or am I concered over nothing?

[Dean Baumgartner]

I had an OEM 2 hp 10 amp 220 volts motor go bad and was replaced
thru warranty but received a 2hp 7 amp 220 volt that seems like it does
not have the power that the original one did but could be me.
I was thinking that normally a 220 volt motor with 7amp capacity would be
a 1 1/2 hp not a 2 hp or am I concered over nothing?
Dave, your 7 amp 220volt motor to deliver a true 2 hp would have to be at 97% efficiency. That's on the high side for even a Marathon Premium Efficiency motor (kind of the gold standard on motors) In that horsepower they claim only 85% efficiency which would require at least 8 amps. Most OEM home equipment motors don't even get close to that efficiency either. Kind of looks like your motor might be a little over rated.

Horse Power = (Volts*Amps*efficiency)/(746)

Dean

[Steven Wilson]

Sounds like it's a 1.5 hp motor. Although the HP formula is brought out all the time folk's forget that the motor isn't 100% efficient. A real world 2hp motor will be around 10 or 11 amps 220v.

[Bob Johnson2]

Dave, your 7 amp 220volt motor to deliver a true 2 hp would have to be at 97% efficiency. That's on the high side for even a Marathon Premium Efficiency motor (kind of the gold standard on motors) In that horsepower they claim only 85% efficiency which would require at least 8 amps. Most OEM home equipment motors don't even get close to that efficiency either. Kind of looks like your motor might be a little over rated.

Horse Power = (Volts*Amps*efficiency)/(746)

Dean
Dean, is 85% a good rule of thumb for small motors? Say anything under 5hp?

[Gary Max]

I would look at it this way.
If you ain't happy and it is underpowered.
That is not the correct motor.
Why should you live with it???????????
That is why you buy new---so it is RIGHT

[Dean Baumgartner]

Bob,

85% is probably the right number for a premium efficiency motor in that size range. For the run of the mill motor something more like 75% would be about as good as it gets.

Dean

[Bob Johnson2]

Bob,

85% is probably the right number for a premium efficiency motor in that size range. For the run of the mill motor something more like 75% would be about as good as it gets.

Dean
Thanks Dean
I tried some of the math on the motors around the shop, the smaller they are the less efficient. Went down to about 50% for 1/4 hp. Thanks for the info, it's something I've been trying to figure out.

[Dean Baumgartner]

Thanks Dean
I tried some of the math on the motors around the shop, the smaller they are the less efficient. Went down to about 50% for 1/4 hp. Thanks for the info, it's something I've been trying to figure out.
Bob,
Happy to help. I'd believe that the 1/4 hp are that low. Most of the big motor manufacturers don't even bother to publish efficiencies on motors under 1 hp.

Dean

[Dave Right]

Thanks Dean and all those that responded.
It gave me knowledge and confidence to call Grizzly.
At first they were going to send me a capacitor but eventually
got the 10 amp motor on the way.!

[Bob Johnson2]

Thanks Dean and all those that responded.
It gave me knowledge and confidence to call Grizzly.
At first they were going to send me a capacitor but eventually
got the 10 amp motor on the way.!
Your membership here has paid for itself already.