Synchronous Speed Motors Flashcards
Describe Synchronous motors speed?
It is a constant speed motor with zero % speed regulation
When is a synchronous motor best suited?
Well-suited to loads that operate below speeds of 500 rpm.
Describe stator construction of a synchronous speed motor
- Similar to a SCIM
- Rotating magnetic field produced exact same way
- Connected either wye or delta
Describe rotor construction of a synchronous speed motor
- Essentially a DC electromagnet with same number of field poles as in the stator
- Poles are salient type
- Poles never change polarity because of the DC field
Why do sync speed motors require a starting aid?
If AC is supplied to the stator and DC is applied to the rotor, the AC field will have a net torque of zero and remain stationary
What are the two ways to start a sync speed motor?
- Amortisseur windings are embedded in the rotors pole face and acts like a SCIM
- A wound rotor motor called a pony motor for high inertia loads
The direct current field pole windings are connected to ______?
Two slip rings mounted on the rotor shaft
What are the 3 common methods of supplying the sync motor with DC field current?
- External converters
- Built-in exciters
- Brushless excites
What is pull-in torque?
the torque required to pull the rotor into synchronism. Once pulled into synchronism, each rotor pole lines up with an opposite polarity stator pole
what is pull-out torque? what are the typical angles this occurs?
- Maximum sustained torque that the motor can develop at sync speed
- May be as high as 60-70°
