SSC JE Electrical 2019 with solution SET-1 A synchronous motor runs at 600rpm, which of the following case is true? P = 12, f = 60 Hz P = 10, f = 60 Hz P= 12, f = 50 Hz P = 8, f = 50 Hz P = 12, f = 60 Hz P = 10, f = 60 Hz P= 12, f = 50 Hz P = 8, f = 50 Hz ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Synchronous speed NS = 120f/PWhenP = 12 & F = 60 then Ns = ?NS = 120f/P = (120 × 60)/12 = 600 RPM
SSC JE Electrical 2019 with solution SET-1 An electric motor in which both the rotor and stator fields rotate with the same speed is called Universal motor Induction motor Synchronous motor DC motor Universal motor Induction motor Synchronous motor DC motor ANSWER EXPLANATION DOWNLOAD EXAMIANS APP In the synchronous motor, the stator and rotor rotate at the same speed.
SSC JE Electrical 2019 with solution SET-1 In the speed-time curve of a train, speed in and time are plotted km/h; hour km/s; hour km/h; sec km/s; sec km/h; hour km/s; hour km/h; sec km/s; sec ANSWER DOWNLOAD EXAMIANS APP
SSC JE Electrical 2019 with solution SET-1 ______starting method CANNOT be used for starting a 3-phase squirrel cage induction motor Star-delta Auto-transformer Rotor-resistance Direct-on-line Star-delta Auto-transformer Rotor-resistance Direct-on-line ANSWER DOWNLOAD EXAMIANS APP
SSC JE Electrical 2019 with solution SET-1 A magnetic circuit is applied with a current that changes at a rate of 5 A/sec. The circuit has an inductance of 2H, then the self-induced EMF is 0.4 V −10 V −4 V −2.5 V 0.4 V −10 V −4 V −2.5 V ANSWER EXPLANATION DOWNLOAD EXAMIANS APP GivenInductance L = 2 HRate of change of current di/dt = 5 A/secSelf induced EMF = − (Rate of change of current × Inductance) = −L(di/dt)= −(5 × 2) = −10V
SSC JE Electrical 2019 with solution SET-1 Identify the INCORRECT statement with regards to synchronous motors The field winding is placed on the rotor It is a constant speed motor The armature winding is placed on the stator It is a self-starting machine The field winding is placed on the rotor It is a constant speed motor The armature winding is placed on the stator It is a self-starting machine ANSWER EXPLANATION DOWNLOAD EXAMIANS APP A synchronous motor is not a self-starting motor. You can check out this article why synchronous motor is not self starting
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