no load test & short ckt test of Induction Motor

Forums Community no load test & short ckt test of Induction Motor

This topic contains 2 replies, has 3 voices, and was last updated by Profile photo of vedprakash vedprakash 2 years, 7 months ago.

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  • #339

    Suhel
    0 votes

    what is no load test & short ckt test of Induction Motor ?

    explain its equatin for finding efective Resistance, Reactance for both test..?
    also explain how to find eficiency..

    #340
    Profile photo of Kiran Daware
    Kiran Daware
    Keymaster
    26 votes
    Points: 265
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    No load test on induction motor

    This test is carried out on an induction motor running without any external load and at rated voltage and rated frequency. No load test on an induction motor gives information about excitation current and no-load rotational losses (i.e. windage, friction and core losses).

    Rotor current is negligible under no-load condition and, hence, the rotor copper losses are also negligible. Thus, the total input power measured under no-load is equal to the sum of stator copper losses and the rotational losses.

    PNL = PCu1 – Prot

    Where, PCu1 = stator copper loss = 3INL2Rw1

    You can learn more about this test at the following link: No-load test on an induction motor.

    Blocked rotor test or short circuit test

    In blocked rotor test, the rotor of induction motor under test is locked by means of a belt or other mechanical arrangement. A low voltage is applied at the stator terminals. Because, if full voltage is applied then the current through the stator winding would be high enough to overheat and damage the stator winding. Also, this test is conducted at 1/4th of the rated frequency. This test is carried out to find short circuit current at normal voltage, leakage reactance and starting torque of the motor.

    Learn more about the blocked rotor test at: Blocked rotor test.

    #348
    Profile photo of vedprakash
    vedprakash
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    0 votes
    Points: 0

    Why block rotor test is conducted on 1/4 of rated frequency.????

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