· The winding in which the number of slots and poles is equal is called concentrated winding.
· If the number of coils in the winding is one per pole phase, then it is called concentrated winding.
· In this type of winding, one coil side is installed in each stator slot.
· By using this type of winding, maximum output voltage is obtained, but the voltage obtained is not completely sinusoidal.
A 4-pole star connected; three phase alternator has 6 slots per pole per phase in the stator. What is its slot angle in degree?
At what speed, a 4-pole alternator has to be driven, so as to generate a voltage at a frequency of 25 Hz? frequency of 25 Hz?
What is a Synchronous condenser?
If the speed of a 3-phase, 400 V, 50 Hz synchronous motor is trebled, the efficiency of the machine will _________.
A three-phase star-connected synchronous alternator of rating 22 kVA, 20 kV, 50 Hz has synchronous reactance of 8 Ω per phase. The induced voltage per phase is 20 kV and the line terminal voltage is 15 kV. Find the 3-phase maximum power of the machine.
Which of the following statements are true for synchronous motor losses?
A)Friction and windage losses increase with the cube of speed.
B)The Eddy current loss is reduced by laminating the core.
C)Copper losses are independent of load.
D)Core losses increase with the square of the load.
Which of the following statements are INCORRECT about auxiliary motor starting in synchronous motors?
A) The function of the auxiliary motor is to run the synchronous motor at a speed less than its synchronous speed.
B) The rating of the auxiliary motor is much lower than that of the synchronous motor.
C) This method is used only for loaded synchronous motors.
D) Auxiliary motor starting is not a commonly used starting method in modern days.
In a synchronous machine having a salient pole field structure, the pole shoe covers about _________ of the pole pitch.
The eddy current losses in a synchronous motor are 100 watts at 100 Hz. Find the frequency, if the losses are to be reduced to 25 W?
