Electrical Machines Objective Questions
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Find the developed torque DC Series Motor having armature resistance of 0.2 Ω and taking armature current of 60 A is connected to 250 V supply. Considered brush drop of 1 V each.
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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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On what factors the speed of dc motor depends?
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Swinburnes test is applicable to
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Which type of DC Motor is preferred for Paper mills?
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Which type motors are preferred for lathes?
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If the full load speed of 3phase, 50Hz induction motor is 950 rpm, what is its half load speed nearly equals to?
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A DC motor with armature resistance of 0.5 ohms connected directly to a 220 Volt supply. If the armature is stationary then the current flowing through the armature is
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In a DC Shunt Motor if the load current increases then field flux
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For a DC Shunt Motor having armature resistance of 0.5 Ω and 2 A armature current at noload, when the armature current is changed to 20 A at loaded condition the speed is 1000 r.p.m. What is the speed at noload?
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In the 3phase induction motor, the resultant flux is of a constant nature and is
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The armature of a DC motor is laminated to reduce
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In a 3phase induction motor, torque and supply voltage are related as
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The power factor of an induction motor operating at no load will have a value around
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In electric locomotive which of the following motor are used ?
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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 rotor slots are slightly skewed in squirrel cage induction motor to
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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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Which of these types of motor is used in elevators?
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Which type of motors are preferred in lifts?
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The armature resistance of a permanent magnet dc motor is 0.8 W. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be
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Semi closed slots or totally closed slots are used in induction motors, essentially to
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If an induction machine is run at above the synchronous speed it acts as
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A DC Shunt Motor having shunt field resistance of 250 Ω and armature resistance of 0.5 Ω is connected to 250 V supply and load current of 21 A. What is the back emf generated ?
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What is the emf generated by a 4 pole Lap connected DC Motor rotating at 1500 rpm having 1000 conductors and useful flux per pole is 0.4 mWb.
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Which type of motors uses slip rings?
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Which of the following motor is expensive for same Kw output rates?
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In DC series motor the speed is ______________ proportional to the armature current.
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The speed of a 3phase induction motor operating in its stable region
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A DC compound motor has
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