Electrical Machines A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.5 p.u 0.125 p.u 0.25 p.u 0.75 p.u 0.5 p.u 0.125 p.u 0.25 p.u 0.75 p.u ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In a synchronous machine, if φ is the flux per pole and f is the frequency of the emf induced E then E ∝ φ/f E ∝ 1/(φf) E ∝ φf E ∝ f/φ E ∝ φ/f E ∝ 1/(φf) E ∝ φf E ∝ f/φ ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The emf induced in the dc generator armature winding is DC AC and DC None of these AC DC AC and DC None of these AC ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If Kh is hysteresis constant, f is supply frequency, Bm maximum flux density in core of transformer, the expression of hysteresis loss in transformer, is given by KhfBm3. KhfBm. KhfBm1.6. Khf2Bm1.6. KhfBm3. KhfBm. KhfBm1.6. Khf2Bm1.6. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Find the number of poles required, when the frequency is 50Hz and speed of the motor is 500 rpm? 5 10 12 24 5 10 12 24 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A DC shunt generator builds up to a voltage of 220 V at no load while running at its rated speed. If the speed of the generator is raised by 25% kepping the circuit conditions unaltered, then the Voltage to which the machine would build up will increase to value lying between 220 V and 1.25 times 220 V increase to 1.25 times 220 V not change and remain at 220 V increase to a value greater than 1.25 times 220 V increase to value lying between 220 V and 1.25 times 220 V increase to 1.25 times 220 V not change and remain at 220 V increase to a value greater than 1.25 times 220 V ANSWER DOWNLOAD EXAMIANS APP
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