Electric Motor Current Draw

[Butch627]

As an example. I have an air compressor that came from the factory with a 3hp motor. I find a replacement 5hp motor with the same rpm, frame, and shaft size at a great price. Would this draw the same current as did the 3hp with the same load, slightly more, or the current on its tag? Would it have a much higher starting amperage than the 3hp?

Same question for an industrial fan?

For the sake of this discussion the breaker, cables, and starter would all be rated to handle the larger motor.

 

[Jaybird1980]

As an example. I have an air compressor that came from the factory with a 3hp motor. I find a replacement 5hp motor with the same rpm, frame, and shaft size at a great price. Would this draw the same current as did the 3hp with the same load, slightly more, or the current on its tag? Would it have a much higher starting amperage than the 3hp?

Same question for an industrial fan?

For the sake of this discussion the breaker, cables, and starter would all be rated to handle the larger motor.

It will have higher start up amps. The running amps with the exact same load will be higher also. How much depends on what voltage and the efficiency of the old motor and new motors.

 

[greg]

It will have higher start up amps. The running amps with the exact same load will be higher also. How much depends on what voltage and the efficiency of the old motor and new motors.

A 5hp motor driving 3hp of load will draw similar current as a 3hp motor driving 3hp of load.

 

[Jaybird1980]

A 5hp motor driving 3hp of load will draw similar current as a 3hp motor driving 3hp of load.

Similar but more, unless the load on the 3hp was near max.
That's why I said it will depend on efficiency.

You would never have a 3hp motor turning a 3hp load that would be overloaded.

 

[smokingman]

Electrical Motors - Full Load Amps

Full load amps for single and 3-phase 460 volts, 230 volts and 115 volts electric motors.

www.engineeringtoolbox.com

 

[smokingman]

Similar but more, unless the load on the 3hp was near max.
That's why I said it will depend on efficiency.

You would never have a 3hp motor turning a 3hp load that would be overloaded.

And on the type of motor. A different type can have a very different curve.

 

[PapaScout]

Current, capacitance, electrical pressure and resistance - these are just words people use to feel superior. You'll be okay but post a video just in case!

 

[smokingman]

Current, capacitance, electrical pressure and resistance - these are just words people use to feel superior. You'll be okay but post a video just in case!

Ohm...mmmmmmmm lol.

 

[Tactically Fat]

Dammit. I speak fluent English.

But I tell you hwhat - I most certainly don't speak electricity.

those of you who can and do - more power to y'all.

 

[smokingman]

Dammit. I speak fluent English.

But I tell you hwhat - I most certainly don't speak electricity.

those of you who can and do - more power to y'all.

When I was 7 my dad was electrocuted at cummins engine plant 1. He was working on a machine and an idiot took his lock off,and reset it(His supervisor). He was inside. He was badly electrocuted and had burns. He also had to wear patches over his eyes for several weeks(after getting out of the hospital),so he could not even see.
He proceed after that to instill not a healthy fear,but paranoia of anything electrical in me.

After the military I wanted to be over pretty much the only irrational fear I had(if I had a choice I would not touch a light switch back then). So what did I do? Went to college for electronics engineering to fully understand electricity(still do not lol). I am still cautious with electricity,but no longer have an unhealthy fear of it.

 

[rhamersley]

Current, capacitance, electrical pressure and resistance - these are just words people use to feel superior. You'll be okay but post a video just in case!

 

[Jaybird1980]

When I was 7 my dad was electrocuted at cummins engine plant 1. He was working on a machine and an idiot took his lock off,and reset it(His supervisor). He was inside. He was badly electrocuted and had burns. He also had to wear patches over his eyes for several weeks(after getting out of the hospital),so he could not even see.
He proceed after that to instill not a healthy fear,but paranoia of anything electrical in me.

After the military I wanted to be over pretty much the only irrational fear I had(if I had a choice I would not touch a light switch back then). So what did I do? Went to college for electronics engineering to fully understand electricity(still do not lol). I am still cautious with electricity,but no longer have an unhealthy fear of it.

Respect it, don't fear it.
That's what I learned.

 

[Frosty]

Respect it, don't fear it.
That's what I learned.

And then cuss it when it unexpectedly bites you

To the op, if the 5 hp motor won’t work, check out www.automationdirect.com
Good prices and good customer service.