Electrical Machines Objective Questions
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When the armature current of 5 Amp is flowing through the dc motor the torque produced is 47 Nm. Keeping the speed constant if the armature current is increased to 7 amp, calculate the new torque. Assume losses to be constant.
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Counter emf of a DC motor
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On what factors the speed of dc motor depends?
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The armature of DC motor is laminated
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The back emf produced in a dc motor depends on
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In electric locomotive which of the following motor are used ?
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A 4 pole wave wound dc motor having flux per pole of 9.56 X 103 Wb contains 460 armature conductors. Calculate the back emf produced when it is running at a speed of 1500 rpm.
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Swinburnes test is applicable to
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The speed of a motor falls from 1100 r.p.m at noload to 1050 r.p.m at rated load. The speed regulation of motor is
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Which of these types of motor is used in elevators?
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Width of a carbon brush should be equal to
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The shaft torque of a dc motor is less than the electromagnetic torque because of
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A 4 pole wave wound dc motor having flux per pole of 9.56 X 10^{3} Wb contains 460 armature conductors with armature resistance of 0.6 ohm. Calculate the starting current flowing through the armature if the supply voltage is 240 volt.
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In DC series motor the speed is ______________ proportional to the armature current.
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DC Motor
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A 230 volt dc motor has an armature winding resistance of 0.5 ohm. Calculate the emf induced by the motor if the full load armature current is 23 ampere.
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A dc motor with armature resistance of 0.5 ohms connected directly to a 230 Volt supply. If the armature is stationary then the current flowing through armature is
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DC Motor
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DC Motor
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A compound motor has
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DC Motor
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In case of a dc motor the ratio E_{b} / E is indicative of
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The direction of rotation of a D.C. series motor can be changed by
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The dc motor which can provide zero speed regulation at full load without any controller, is
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The output power of a dc motor is given by
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DC Motor
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Two identical loss less series motors connected in series across a dc supply voltage, runs at speed of N_{1} and N_{2}, then ratio of their output power is
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The armature of a DC motor is laminated to reduce
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Which motor used in Lathe machine?
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Which type of motors are preferred in lifts?
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