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17.When a stationary 3-phase induction motor is switched on with one phase disconnected (a) It will start but run very slowly. (b) It will make jerky start with loud growling noise. (c) Remaining intact fuses will be blown out due to heavy rush of current. (d) It is likely to burn out quickly unless immediately disconnected.
Learn MoreAug 15, · Single-Phase Induction Motor • Constructionally, this motor is, more or less, similar to a polyphase induction motor, except that (i) its stator is provided with a single-phase winding and (ii) a centrifugal switch is used in some types of motors, in order to cut out a winding, used only for starting
Learn More14 Starting methods for induction motors Squirrel-cage rotor: (i) Direct-on-line starting (DOL) With this method, starting current is high and may cause interference with supplies to other consumers. (ii) Auto transformer starting With this method, an auto transformer is used to reduce the stator voltage, E1, and thus the starting current. However, the starting torque is seriously reduced so
Learn MoreControl system for polyphase induction machines: 1992-08-18: Verbos: 318/809: 4950970: Induction motor control system: 1990-08-21: Davis, Jr. et al. 318/809: 4800326: Apparatus and methods for controlling induction motors: 1989-01-24: Unsworth: 318/729: 4752725: Control apparatus for three-phase induction motor: 1988-06-21: Ominato: 318/807
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Learn MoreJun 21, · 4. Polyphase/3 phase induction motors are self-starting and are more efficient. On the other hand single-phase induction motors are not self-starting and are less efficient. 6. Per unit of output. the polyphase/3 phase machine is very much cheaper. 7. Power factor of a single-phase motor is lower than that of polyphase motor of the same rating. 8.
Learn More15. For the application requiring high starting torque and minimum starting current, the most suitable starting method will be? a) Auto transformer starting method b) Reactance starting method c) DOL method d) Star-Delta method View Answer
Learn More3-Phase induction machine construction • 3 stator windings (uniformly distributed as in a synchronous generator) • Two types of rotor: –Squirrel cage –Wound rotor (with slip rings) The rotating magnetic field • The basic idea of an electric motor is to generate two magnetic fields:
Learn MoreADVERTISEMENTS: The following points highlight the methods of electrical breaking used in polyphase induction motors. The methods are: 1. Plugging (or Counter-Current Braking) 2. Dynamic (or Rheostatic) Braking 3. Regenerative Braking. Method # 1. Plugging (or Counter-Current Braking): Plugging can be achieved in an induction motor merely by reversing two of the three phases which []
Learn MoreA polyphase induction machine operated by an inverter drive system. The machine is constructed with concentrated full span windings. Twelve or more phases are used to sufficiently cover the airgap region, in contrast to the conventional three phases using distributed and chorded windings. Substantial efficiency and starting torque benefits are thereby obtained.
Learn MoreApr 18, · IEEE standard test procedure for polyphase induction motor and generators, IEEE standard 112-1996, New York, May 1997. J. Nagrath, D. P. Kothari, Electrical Machines, 2nd ed., Tata McGraw Hill, New Delhi. G. C. Soukup Cause and analysis of stator and rotor failures in three phase squirrel cage induction motors, IEEE Trans. Ind.
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