Electrical Machines Objective Questions
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Capacitor fitted with ceiling / table fans is of the value of
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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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What type of dielectric material is used in capacitors used for fans and for power factor correction?
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What is/are the necessary conditions for voltage build up in self excited generator?
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The effect of  on main field flux is armature reaction?
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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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Which single phase motor is used for a refrigerator?
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At slip s = 1 torque developed in machine is
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Which of the following motor is used in grinders?
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Slip speed is the
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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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Type of single phase motor having highest power factor at full load is
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If the field current is reduced to zero the maximum power developed by alternator 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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For a single phase capacitor start induction motor which of the following is valid?
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Armature flux is.............with respect to main field flux or main field poles?
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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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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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Capacitor start capacitor run provides
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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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No load saturation characteristics are plotted between
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Induction motors have the advantage 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
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Which motors are preferred for refrigeration and air conditioning in smaller units?
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Why are capacitors used with large AC induction motor?
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Which of the following motor used in hair dryers?
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Voltage across the open circuited field termninals of a synchorous machine under slip test is
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Cross magnetization effects which of the following?
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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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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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