Constructional Features of Three-Phase Synchronous Motors Flashcards
What is the name of the squirrel-cage winding placed near the surface of the field poles in a synchronous motor?
Amortisseur winding (or damping winding)
What are the two functions of this squirrel-cage winding in a synchronous motor?
The amortisseur windings main purpose is to dampen any momentary speed fluctuations that may occur when the mechanical load on the motor is suddenly changed. Its secondary purpose on some synchronous motors is to start the motor and accelerate is up to speed.
Is the rotor field winding in a synchronous motor being fed with alternating current or direct current?
Direct current
How is the field excitation supplied to the rotor?
through slip rings and brushes
How are the field terminals in a synchronous motor identified?
F1 & F2
What is the purpose of the end bells and bearings in a synchronous motor?
To support the rotor shaft, permit it to rotate, and keep it in proper alignment with the stator
When are external converters normally used to supply the field excitation to a synchronous motor?
When the DC supply is required for other loads in the plant
How is the level of DC excitation controlled in an external converter?
By placing a rheostat in series with the DC supply
Where is a DC exciter for a synchronous motor normally mounted?
On the same shaft as the synchronous motor
How is the level of DC excitation controlled in a built-in exciter?
By varying the exciters voltage output, by using a rheostat in series with the shunt field of the exciter
What provides the DC excitation in a synchronous motor with a brushless exciter?
a three-phase alternator and rectifier assembly mounted on the rotor of the synchronous motor
How is the level of DC excitation controlled on a synchronous motor equipped with a brushless exciter?
by varying the field current to the brushless exciter
