Electrical Machines Objective Questions
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Capacitor start capacitor run provides
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Capacitor fitted with ceiling / table fans is of the value of
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Which motors are preferred for refrigeration and air conditioning in smaller units?
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What is/are the necessary conditions for voltage build up in self excited generator?
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Slip speed is the
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Which of the following motor is used in grinders?
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Why are capacitors used with large AC induction motor?
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Armature flux is.............with respect to main field flux or main field poles?
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Voltage across the open circuited field termninals of a synchorous machine under slip test is
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Two 3phase AC generators are such that one has twice the linear dimensions of the other. The field windings of each are excited to give identical sinusoidal airgap flux density waveform. Both have the same number of stator slots and identical winding patterns. The conductor/slot in a big generator is K times that of the smaller one. The value of K to get equal no load voltage at same frequency is
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Type of single phase motor having highest power factor at full load is
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Torque angle of a synchorous machine operating from a constant voltage bus is usually defined as the space angle between
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A 3phase, alternator has generated emf per phase of 230 V with 10% 3rd harmonic and 6% 5th harmonic content. Calculate rms line voltage for star connection.
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No load saturation characteristics are plotted between
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What type of dielectric material is used in capacitors used for fans and for power factor correction?
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For a single phase capacitor start induction motor which of the following is valid?
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Find the synchronous reactance of alternators in which a given field current of 200 A on short circuit and a generated emf of 50 V on open circuit. Armature resistance is 0.1 ohm
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A 3phase, alternator has generated emf per phase of 230 V with 10% 3rd harmonic and 6% 5th harmonic content, find rms line voltage for delta connection?
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Induction motors have the advantage of
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If the field current is reduced to zero the maximum power developed by alternator is
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Which of the following motor used in hair dryers?
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The effect of  on main field flux is armature reaction?
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Cross magnetization effects which of the following?
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Which single phase motor is used for a refrigerator?
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A three phase induction motor has a synchronous speed of 1500 rpm the machine runs at 1460 rpm at a particular load. The slip at this load is ___________.
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Two singlephase alternators operating in parallel have induced EMFs on open circuit of 230âˆ 0Â° and 230âˆ 10Â° volts and respective reactance of j2 Î© j3 Î© calculate the terminal voltage
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At slip s = 1 torque developed in machine is
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If dimension of all the parts of a synchorous generator and the number of field and armature turns are double, then generated voltage will change by a factor of
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Two singlephase alternators operating in parallel have induced EMFs on open circuit of 230âˆ 0Â° and 230âˆ 10Â° volts and respective reactance of j2 Î© j3 Î© calculate the terminal voltage, find the power delivered by each of the alternators to a load of impedance 6Î©(resistive)
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For the above problem, find the induced voltage of an alternator of it is to deliver a load of 100 A at power factor of 0.8 lagging with terminal voltage of 200 V.
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