05 (1p,): The square loop shown has a side of 10 em and is moving to the right w

Question

05 (1p,): The square loop shown has a side of 10 em and is moving to the right with a velocity of 36 km/hr in the presence of a magnetic field of B-06 T. What is the voltage induced in the coil? 61p How can the reactive power delivered by a synchronous generator be increased? 07 (2p A 50-Hz synchronous motor has 4 poles, (a) what is the synchronous speed? (b) How can the direction of rotation of this motor be reversed? 07 (20 p.): A 13.8-kV, 20-MVA, 0.9-power-factor-lagging, 60-Hz,four-pole Y-connected synchronous generator has a synchronous reactance of 2.5 ? and an armature resistance of 0.2 ?. When this generator is operating at rated conditions, (a) What is the output power (b) What is the output reactive power (c) What is the load current?

Explanation / Answer

answer of q.5(1p)

here given quantities are

velovity (v) = 3.6 km/hr

               3.6*(1000/3600) m/sec

B=0.6 T

length (L)=10 cm

              = 10/100 m

induced emf=BvL

   = 6mV

answer of Q.6

A synchronous generator is capable of producing active as well as reactive power. When the rotor is over excited, a synchronous Generator delivers reactive power . In general a synchronous generator works at 0.9–0.97 lagging power factor.

If we consider a synchronous motor, the motor consumes active power but can deliver deliver reactive power when rotor circuit is overexcited with DC current. In general if a synchronous motors rotor is overexcited it works at leading power factor. If the motor is under excited, then it consumes reactive power in addition to Active power for its operation.

answer of q.7

Ns=120(f/P)

here f=50 Hz and P=4

so Ns= 3000rpm

Direction of rotation can be changed by altering the phase sequence of the supply

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