The speed of a dc motor can be controlled by the variation of
1. armature voltage. 2. field current. 3. armature circuit
resistance. 4. angle of brush shift.
Which of the statements given above are correct?
(a) 1,2 and 3 (b) 2,3 and 4
(c) 1,3 and 4 (d) 1,2 and 4
We say that if voltage in a power system is increased,for a constant power the current will decrease (by P=VI). isn't this in disagreement with the ohms law(I propotional V;resistant const.).Since the resistance of transmission lines remains constant,shouldn't inc in voltage cause inc in current across the transmission line? I have read many articles across the net but still couldn't this figure this out. :( Guyz plz assist me with dis..:)..
In DC current-excitation to transformer, why it sucks more current? Eventhough there is no power transfer between primary and secondary? R is very low so it should suck less current only na thn y its current increases?
WHAT ARE THE SITE TEST APPLIED ON A SURGE ARRESTORS? DO MEGGER TEST APPLIED ON SURGE ARRESTOR? IF YES THEN WHAT ARE THE ACCEPTED IR VALUE REQUIRED FOR SURGE ARRESTORS FOR VOLTAGE LEVEL 11KV, 33KV, 66KV 132KV, 220KV AND 400KV?
In a incandescent bulb, if the glass is punctured, and then power is supplied, the tungsten filament blows up with a flash.Why?
why capacitor bank shorted by resistance ( 3 terminal )
why the neutral point in connnection oscillates?
I have a drawing of a wound rotor induction motor for a crane. This crane motor has 5 forward speeds & 5 reverse speed implemented of course with different amount of resistance for each speed setting selected. What has got me scratching around is the fact that 8 of the 10 speed selections switch in uneven (unbalanced) amounts of resistances on each of the 3 connections to the motor's rotor.Can this be possible? I would have assumed this would produce unbalanced rotor currents and therefore vibration in the motor. I would greatly appreciate anyone's comments on this. Many thanks, Confused.
what is electrostatic presipitator in thermal power plant,and why it is used?
how braking & making capacity of circuit breaker are calculated?
why energy storing capacity of magnetic field is much higher than electric field ?
what are the range of memory address in plc for L&T lx7 4A
why D.C excitation is given to sunchronous motor?
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