Electrical Machines Objective Questions
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DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of
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Two DC series motor are connected in series and are driving the same mechanical load. If the motors are now connected in parallel the speed will become
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When two DC series motors are connected in parallel, the resultant speed is
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In speed control of DC Series motor, speed lower than the rated speed can be obtained by
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Field divertor method of speed control of a DC series motor gives speed above rated one due to reduction of
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The main disadvantage(s) of the ward-Leonard system is/are
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In a seperately excited DC Motor if field current is increased, it will
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If the handle of a three point starter goes to back to OFF position, it may due to
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In which of the following DC Motor the ratio of starting torque to full load torque is minimum?
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Which of the following DC Motor use 4-point starter?
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High inrush of current during a starting of a DC motor can efficiency be restricted to a safer value by increasing the _________________ resistance.
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For a given torque, reducing divertor resistance of a DC series motor
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If starter is not used with large DC motor for starting, it will
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The field divertor resistance for a DC series motor is of order of
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If the no-voltage release in a DC motor starter fails to operate on failure of supply, on resumption of supply the motor will
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For starting a DC motor a starter is required because
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Variation in speed by ward-Leonard control of DC motors occurs due to variation in
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In which of the following speed control of DC motor the speed obtained is below than the rated speed?
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Which DC motor will have least percentage increase of input current, for the same percentage increase in the torque
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Which of the following DC Motor requires 3 point starter?
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The armature voltage control is considered suitable for a DC motor driven at constant
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The current drawn by a DC motor at the time of starting is
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Neglecting all losses, the developed torque (T) of DC separately excited motor, operating under constant terminal voltage is reduced to its output power (P) as
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A DC series motor is running with a divertor connected across its field winding. If the divertor resistance is reduced then the speed of the motor will
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To get the speed of DC motor is more than normal without wastage of electrical energy _____________ is used.
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In a DC Motor 3 point starter is used
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In case of DC Shunt Motor, the speed will____ if the voltage increases, neglecting armature saturation.
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If an additional resistance is connected in series with a DC series motor operating at rated speed, the speed of the motor will
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Direct-on-line (DOL) starters are not suitable for starting large DC motors, because
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Ward Leonard control is provides speed control
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Electrical Machines - 7
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