81
|
Describe any two features of the Double cage
induction motor.
|
|
Features of Double cage induction motor
|
82
|
Describe the conditions to be necessary for the cascade
operation of the three phase induction motor.
|
|
Cascade operation of three phase
induction motor
|
83
|
Which type of cascade connection of the induction
motor should provide very low or zero torque?
|
|
Differential connection
|
84
|
What should be the frequency of the rotor induced emf
in the injected emf speed control method of induction motor?
|
|
The frequency of the injected emf should be same as the slip frequency
( rotor frequency ).
|
85
|
What are the advantages of the Kramer speed control
of the induction motor?
|
|
Advantages of Kramer speed control
|
86
|
Which parameter the locus of the circle diagram
represents?
|
|
Rotor current as refer to stator side
|
87
|
Describe the method to find out no load parameter G0
and B0 of the three phase induction motor.
|
|
No load parameters
I0 = VY0
And W0 =
3G0V2
G0 = W0
/ 3V2
And B0 = √
(Y02 – G02)
|
88
|
Give the reason : The one wattmeter shows negative
reading in the no load test of the three phase induction motor.
|
|
Induction motor at no load
W1 α Cos (
30 + Ф )
W2 α Cos (
30 – Ф )
Where Ф is the load
power factor
|
89
|
Which parameters can find out by performing blocked
rotor test in the three phase induction motor?
|
|
Short circuit current at normal voltage
Power factor Cos Фsc at short circuit
Total winding impedance Z01, reactance X01 and
resistance R01 as referred to the stator side
|
90
|
Describe the effect on torque and starting current
if the supply voltage is reduced by 50% in the three phase induction motor?
|
|
Effect of supply voltage
|
91
|
Is there any effect on power factor by using primary
resistor starter in the three phase induction motor?
|
|
The power factor improves slightly due to resistors connected to the
line.
|
92
|
Describe the effect of speed on the rotor induced
emf.
|
|
Effect of speed on rotor induced emf
|
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