Universal motors

[Alberto8]

Hi:
I would like to know the following:
How many changes the speed in an Universal motor (series, parallel or compund) if supplied with 60Hz or 50Hz.
Thanks

 

[Skogsgurra]

What is the question?

How many (times per second the flux/speed/torque) changes when motor is fed with 50 or 60 Hz?

The answer is: Flux changes 50/60 times per second. Speed changes very little - it may have a little 100/120 Hz ripple on top of the constant speed. Torque changes 100/120 times per second.


Gunnar Englund

http://www.gke.org

 

[laundry]

Aiberto8
What type of motor are you talking about is it ac or dc,as you have indicated series and compound.series and compound are DC.
skogsgurra is right what is the question.

Barry.

 

[Skogsgurra]

Welcome back Barry! Feel better now?

A universal motor is a series (usually) motor used in power drills, polishers and similar hand-held machines. It can be run off DC or AC - that's why it is called a universal motor.

Gunnar Englund

http://www.gke.org

 

[laundry]

Alberto8
At 60hz rpm= 3600.
At 50hz rpm= 3000
The current will change direction every 10ms and a peak in torque 100 times per second.But the torque willalways remain undirectional,and the speed fluctuations will not be noticeable because of the amoothing effect of the armature inertia.

Skogsgurra is also correct.
Thanks Gunnar very bad day yesterday.

Barry.

 

[Skogsgurra]

Sorry Barry, not much better today.

A universal motor is not at all frequency dependent. If it were, what speed would DC result in?

Gunnar Englund

http://www.gke.org

 

[laundry]

Hi Gunnar.
I was off yesterday.I Have worded it badly the increase in speed was related to a standard ac motor frequency increase.As you have pointed out universal motors are not frequency dependent correct.Series motors for use on ac,supplies are always designed with fully laminated construction ( to limit eddy current lasses due to the pulsating flux in the magnetic circuit ),and are intended to run at high speeds of 8,000 to 12,000 at rated voltage.
hope I have redeemed my self.

Barry.

 

[powerjunx]

GUYS,
Alberto is confuse as posting his threads.

Universal motor is an AC/DC machine. Since, it was a DC. He assume that it can be a series, shunt, compound connected.

But the real question, he asked was in the AC operation.. the latter was already answered by skogsgurra.