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1-Dont try to cram or spend more time here just read it fast and cover syllabus then practice MCQ's cheptor of same topic to check your progress. . |
2-Wrong options are also given but dont concentrate there, Right answer is in bold format. |
Q21 ⇒ The starting torque of an induction motor varies as 1/f2 [other wrong options] [Discuss in forum] f 1/f f2 |
Q22 ⇒ The phenomenon of crawling in a 3-phase induction motor may be
due to 7th space harmonics of air-gap field. [other wrong options] [Discuss in forum] unbalanced supply voltage. 7th time harmonics of voltage wave. 5th space harmonics. |
Q23 ⇒ In comparison to a resistance start motor, the capacitor start motor
has |
Q24 ⇒ In a transformer, the exciting current will be in phase quadrature
with the impressed voltage provided both the leakage impedance drop and the core loss are ignored. [other wrong options] [Discuss in forum] oniy the leakage impedance drop is ignored. only the core loss is ignored only the no-load copper loss is ignored. |
Q25 ⇒ For starting a small induction motor DOL starter is used in place
of iron clad triple-pole (ICTP) switch as it provides protection against overload and undervo]t. [other wrong options] [Discuss in forum] reduces the starting current. increases the starting torque. improves the power factor and efficiency |
Q26 ⇒ An increase in number of poles of an induction motor results in decrease in maximum pf. [other wrong options] [Discuss in forum] increase in maximum pf. no change in maximum pf. cannot be predicted. |
Q27 ⇒ Two capacitor type induction motors have the main drawback of high cost [other wrong options] [Discuss in forum] low power factor pulsating torque. poor starting torque |
Q28 ⇒ The primary ampere-turns are counter balanced by secondary ampere-turns. [other wrong options] [Discuss in forum] primary flux. increase in mutual flux increase in secondary current |
Q29 ⇒ Primary series resistors are employed in the stator for starting a
3-phase squirrel cage induction motor to reduce voltage applied across the motor terminals [other wrong options] [Discuss in forum] increase the starting torque. improve the pf and efficiency of the motor. increase the motor speed |
Q30 ⇒ The difference between the number of stator slots and that of rotor
slots in an induction motor should not be equal to P, 2P or 5P. It is
essential in order to avoid synchronous cusps. [other wrong options] [Discuss in forum] crawling. magnetic locking noise and vibrations |
Q31 ⇒ Shaded pole motor is provided with laminated salient poles and a squirrel cage rotor. [other wrong options] [Discuss in forum] a commutator a capacitor. a centrifugal switch |
Q32 ⇒ In the transformer circuit mode, the core loss is represented as a shunt resistance. [other wrong options] [Discuss in forum] series resistance. series inductance, shunt inductance |
Q33 ⇒ Which of the following starting methods cannot be used for starting
a 3-phase squirrel cage induction motor? Rotor-resistance. [other wrong options] [Discuss in forum] Star-delta. Auto-transformer. Line resistance. Direct-on-line. |
Q34 ⇒ The outer cage of a double squirrel rotor consists of manganese brass. [other wrong options] [Discuss in forum] red copper bronze. steel. |
Q35 ⇒ In various types of split-phase l-phase induction motors, the starting
torques produced are in the following descending order Capacitor-split, resistor-split, shaded pole. [other wrong options] [Discuss in forum] Capacitor-split, shaded-pole, resistor split. Resistor-split, capacitor-split, shaded pole. Shaded pole, resistor-split, capacitor-split. |
Q36 ⇒ The losses in a transformer are I Copper loss II Eddy current loss III Hysteresis loss. The constant power loss of a transformer is given by II and III only. [other wrong options] [Discuss in forum] I only I and II only I, II and III. |
Q37 ⇒ The speed of an induction motor depends on all of the above [other wrong options] [Discuss in forum] number of stator poles. stator supply frequency input voltage to stator |
Q38 ⇒ Squirrel cage induction motors have the disadvantages of all of the above. [other wrong options] [Discuss in forum] higher starting current and poor starting torque. high sensitivity to fluctuations in supply voltage and low power factor at light-load. no possibility of speed regulation. |
Q39 ⇒ AC series motors in comparison to dc series motors do not have wider air gap. [other wrong options] [Discuss in forum] lesser number of field turns. larger number of armature conductors. larger number of poles with lesser flux per pole. brushes of smaller width. |
Q40 ⇒ The main purpose of performing open-circuit on a transformer is
to measure its core loss. [other wrong options] [Discuss in forum] copper loss. total loss. insulation resistance. |
Or |