Running pump without impeller

[asome_one]

I have a UV sterilizer (JUP-01) that im trying to use against dinos. It has a built in pump attached to the UV light. It is all housed in a single sealed unit. I want to run the unit without the impeller placed as I'm driving the UV with a different pump that has more adjustment.

Is it safe to operate a pump without the impeller? I have tried to google this but have come up with nothing.

 

[ryanjohn1]

Should be ok

 

[asome_one]

Update : I ran it for about 2 hours and noticed the housing of the unit getting extremely hot. So I cut the impeller blades off the impeller and dropped it in. The temperature has since reduced.

 

[Yodaman]

If I would have bought this earlier I could have advised you! Essentially without the impeller, you creat a short, and use an excessive amount of current.

With the rotor in place and spinning inside the magnetic field the electric consumption drops dramatically. That would be why it was so hot without it, and cools down with the rotor back in the housing.

Cutting the fins off the impeller was the right answer for running it on a different pump

 

[gbroadbridge]

If I would have bought this earlier I could have advised you! Essentially without the impeller, you creat a short, and use an excessive amount of current.

With the rotor in place and spinning inside the magnetic field the electric consumption drops dramatically. That would be why it was so hot without it, and cools down with the rotor back in the housing.

Cutting the fins off the impeller was the right answer for running it on a different pump

I don't believe this is correct.

If you remove the rotor from an induction motor it is basically the same as a transformer operating with an open circuit secondary winding.

The current will not increase.

The temperature will increase simply due to the lack of water cooling that is normally supplied by the rotating impeller.

If however, the impeller is jammed, then you would have the situation you mention, which is effectively a short circuited secondary winding.

 

[asome_one]

I don't believe this is correct.

If you remove the rotor from an induction motor it is basically the same as a transformer operating with an open circuit secondary winding.

The current will not increase.

The temperature will increase simply due to the lack of water cooling that is normally supplied by the rotating impeller.

If however, the impeller is jammed, then you would have the situation you mention, which is effectively a short circuited secondary winding.

I am not too familiar with the wiring of it all...but I do know that while this specific unit was operating with an external pump it got extremely hot to the touch. Water was still flowing through the normal paths of the device - As the water exit is directly above the impeller.
Once I plopped the modified impeller back into the unit I noticed the temperature of the unit was still warm but not disconcertingly hot. It ran for about two hours before i noticed and made the change. It has now been running for the past 6-7 hours without getting excessively hot.

 

[Yodaman]

I don't believe this is correct.

If you remove the rotor from an induction motor it is basically the same as a transformer operating with an open circuit secondary winding.

The current will not increase.

The temperature will increase simply due to the lack of water cooling that is normally supplied by the rotating impeller.

If however, the impeller is jammed, then you would have the situation you mention, which is effectively a short circuited secondary winding.

I will admit, I’ve never run a motor without a rotor, but I work with industrial 3 phase motors every day, and the moving magnetic field of the rotor causes a rise in resistance of the windings.

Locking the rotor and applying full power to a motor results in current readings 5x and up of the rated full load amperage.

These same motors often don’t have any external or internal cooling(albeit small, these without cooling are between 0.5hp and 2hp)

This is what led me to my first guess anyways

I think the example you use of a transformer with open secondaries is closer to the motor having the rotor installed with no impeller blades.