On This Page
This set of Electrical and Electronics Engineering Multiple Choice Questions & Answers (MCQs) focuses on Electrical And Electronics Engineering Set 8
Q1 | The starting torque of 3 phase I.M. motor is-------Supply voltage.
- independent of
- directly proportional to
- directly proportional to squre of
- none
Q2 | Squirrel cage I.M. motor suffers from disadvantage of -- starting torque.
- low
- high
- pulsating
- none
Q3 | Rotor winding of 3 phase I.M. is generally------
- star connected
- delta connected
- series connected
- parallel connected
Q4 | the direction of rotating magnetic field depends upon
- the direction of rotating magnetic field depends upon
- phase sequence of supply voltage
- supply current
- supply voltage
Q5 | The relation among synchronous speed(Ns),rotor speed(Ns),slip(s)
- n=(s-1)ns
- n=(1-s)ns
- n=(1+s)ns
- n=s xns
Q6 | slip of I.M. is given by the formula
- (ns-n)/ns
- ns/(ns-n)
- ns/n
- (ns-n)
Q7 | when rotor of 3-phase I.M.motor is blocked stopped forcibly, the slip is ---
- 0
- 0.5
- 0.1
- 1
Q8 | The quantity (Ns-N) with respect to I.M. motor is called----
- slip
- frequency
- relative speed
- speed of rotor
Q9 | frequency( fr) of induced emf in rotor of I.M. is given by --
- s2.f
- f2.s
- s/f
- s.f
Q10 | At any given slip s the rotor induced emf (E2r) is ----
- f/e2
- f.e2
- s.e2
- s/e2
Q11 | Rotor induced emf is maximum when slip is --
- 0
- 1
- 0.5
- 0.05
Q12 | At any given slip s the rotor reactance is ----
- s.x2
- s/x2
- fr.x2
- f.x2
Q13 | The reactance of the rotor circuit of 3-phase I.M. is maxium at
- no-load
- full-load
- half of full load
- start
Q14 | which mathematical expression represents correct formula to find rotor current (I2)during starting
- e2. √(r2+x2)
- s.e2 / √(r22+x22)
- e2/ √(r22+x22)
- s.e2. √(r2+x2)
Q15 | which mathematical expression represents correct formula to find rotor current when running at slip s.(I2r)
- e2. √(r2+x2)
- s.e2/ √(r22+x22)
- e2. √(r2+x2)
- s.e2/ √(r22+s2x22)
Q16 | The rotor current in 3-phase I.M. is-----slip
- inversely proportional to slip
- directly proportional to slip
- independent of
- directly proportional to square of slip
Q17 | If slip of a 3-phase I.M. increases, the power factor of rotor circuit
- is decreased
- is increased
- remains unchanged
- none
Q18 | The slip ring I.M. has high starting ----with ------starting current.
- low, high
- low, low
- high, low
- high, high
Q19 | the squirrel cage I.M. has ------- starting torque.
- high
- low
- moderate
- very high
Q20 | External resistance is added to rotor winding of slip ring I.M to --------starting torque
- increase
- decrease
- to keep constant
- none of the above
Q21 | For 6 pole 50Hz I.M, sychronous speed of rotating magnetic field is---------
- 1200rpm
- 1000rpm
- 500rpm
- 50rpm
Q22 | For 2 pole 50Hz I.M,sychronous speed of rotating magnetic field is---------rpm
- 3000
- 1000
- 1500
- 500
Q23 | For sychronous speed of rotating magnetic field 1000rpm, for 50 Hz supply,required no of poles =--------
- 6
- 2
- 4
- 8
Q24 | for given no. of poles and if supply frequency reduces, sychronous speed of rotating magnetic field
- remains same
- decreases
- increases
- decreases to half value
Q25 | For 3phase I.M,The synchronous speed of rotating magnetic field is 1000 rpm,speed of rotor is 960 rpm ,then slip is
- 0.04
- 0.02
- 0.01
- 0.021