Motor rated 1 hp and 1.5hp

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Dennis Alwon

Dennis Alwon

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We are hooking up a pool cover that has 2 ratings and both ratings of HP say 120/240V. This is a hydraulic motor and the amp rating is 13 amps @ 1 HP and 19 amps @ 1.5 HP. It doesn't make sense. Can anyone explain this
 
May be there are two windings in the motor ; to be checked with the motor name plate details.
 
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T.M.Haja Sahib said:
May be a case of poor efficiency and poor power factor; to be checked with the motor name plate details.
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And why not mark with worst case as being the rating? That is pretty much what happens with all motors anyway. The motor only uses what it takes to make it run plus whatever load is coupled to it.

Change something like voltage, frequency, number of poles and you have a good reason for a separate rating.
 
Dennis Alwon said:
We are hooking up a pool cover that has 2 ratings and both ratings of HP say 120/240V. This is a hydraulic motor and the amp rating is 13 amps @ 1 HP and 19 amps @ 1.5 HP. It doesn't make sense. Can anyone explain this
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I'm still trying to get my head round the concept of a hydraulic motor taking current.
 
Dennis Alwon said:
There were 2 nameplates on this motor. When the company was called by the GC they said it can be either one.
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The amount of power that a motor delivers is actually a function of the mechanical load being imposed upon the motor. A motor rated for 1HP can have a mechanical load of up to 1HP imposed on it, without the motor stalling out or tripping its overload protective device. A similar statement can be made for a motor rated 1.5 HP. I suspect that if you were to buy two motors from this company, one rated 1 HP and the other rated 1.5 HP, what you would get is two identical motors with different nameplates. In other words, if you have a motor that can handle a 1.5 HP mechanical load, that same motor can also handle a 1 HP mechanical load. If that motor is driving a 1.5 HP mechanical load, it will draw more current than it would if you only have it driving a 1 HP mechanical load.

So disregard the confusion. It was probably a factory error to have placed both nameplates on a single motor. What you have is a motor that is capable of 1.5 HP. Now, tell us what the mechanical load is. Then you can do your calculations of conductor sizes, and overload sizes, and breaker ratings, and all that. If your installation (i.e., the mechanical requirements) only needs a 1 HP motor, then you can size the electrical stuff accordingly.
 
Besoeker said:
I'm still trying to get my head round the concept of a hydraulic motor taking current.
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I interpreted that statement as meaning an electric motor that is driving a hydraulic pump that supplies hydraulic pressure to a hydraulic motor that moves the pool cover into place.
 
It's a game I've seen played recently in the low-end packaged HPU (Hydraulic Power Unit) industry; 1 HP continuous duty, 1.5 HP intermittent duty. They took a page out of the air compressor and power tool mfr's play book. It's a 1 HP motor that will BRIEFLY allow short bursts of added power, but they know that in the application it is designed for, it will never need to. It just looks better in the marketing materials when being sold to people who don't understand it fully, which is the vast majority of consumers.

I would protect it as a 1HP motor.
 
Jraef said:
It's a game I've seen played recently in the low-end packaged HPU (Hydraulic Power Unit) industry; 1 HP continuous duty, 1.5 HP intermittent duty. They took a page out of the air compressor and power tool mfr's play book. It's a 1 HP motor that will BRIEFLY allow short bursts of added power, but they know that in the application it is designed for, it will never need to. It just looks better in the marketing materials when being sold to people who don't understand it fully, which is the vast majority of consumers.

I would protect it as a 1HP motor.
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Got it! Thanks for the heads up.
 
Sorry - been gone all morning and have to leave again.

Yes it is an electric motor that opens and closes the pool cover by reversing the solenoid. Motor runs in one direction and is not two speeds. I can't imagine the load being different whether the cover opens or closes so I expect it to be the same. Did one not too long ago but it did not have two nameplates. I figured in either case I can still run the same size wire and use a 30 amp breaker and be covered.

On another note this is for a pool cover. For some reason this must be GFCI protected and they don't make a 25 amp gfci breaker-- BTW it is 120V not 240V- wired from the factory and cannot be opened in the field. Now a pool pump does not need gfci if I use a 25 amp breaker but the hydraulic pump does.:?:?


This is the same company that wires the system switching the neutral of the circuit. ????

I am about ready to call UL and see what they have to say. The company is of little help.
 
Dennis Alwon said:
Sorry - been gone all morning and have to leave again.

Yes it is an electric motor that opens and closes the pool cover by reversing the solenoid. Motor runs in one direction and is not two speeds. I can't imagine the load being different whether the cover opens or closes so I expect it to be the same. Did one not too long ago but it did not have two nameplates. I figured in either case I can still run the same size wire and use a 30 amp breaker and be covered.

On another note this is for a pool cover. For some reason this must be GFCI protected and they don't make a 25 amp gfci breaker-- BTW it is 120V not 240V- wired from the factory and cannot be opened in the field. Now a pool pump does not need gfci if I use a 25 amp breaker but the hydraulic pump does.:?:?


This is the same company that wires the system switching the neutral of the circuit. ????

I am about ready to call UL and see what they have to say. The company is of little help.
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If they don't make or is hard to get your desired 25 amp GFCI breaker, you can use a 30 amp GFCI breaker and supplement it with a non GFCI 25 amp that also doubles as the motor disconnecting means.
 
So they did not have the cover installed and the motor ran at 12.8 amps. With hydraulics does the motor actually have to work harder under load or should it always be running at ~13 amps
 
kwired said:
If they don't make or is hard to get your desired 25 amp GFCI breaker, you can use a 30 amp GFCI breaker and supplement it with a non GFCI 25 amp that also doubles as the motor disconnecting means.
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Yes I know but that would mean changing our hookup. I don't understand why it needs GFCI protection and the pool doesn't when connected at 25 amps. I think I could still use a sp 30 gfci.
 
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