1.A cumulative compound motor is operated as a shunt motor with its series field disconnected, has an armature current of 100 A and at a shunt field flux of 0.09 Wb develops a torque of 75 N.m. When the series field is connected at the same armature current, the motor develops a torque of 90 N.m. Calculate the increase in flux produced by the series field. *

a.22 mWb

b.18 mWb

c.25 mWb

d.20 mWb

2.A 250 kVA transformer has a full load copper loss of 3 kW and an iron loss of 2 kW. Calculate the maximum efficiency, assuming the power factor of the load is 0.80. 

a.98.45%

b.96.48%

c.97.61%

d.95.78%

3.A shunt generator has a field resistance of 60 Ω. When the generator delivers 6 kW, the terminal voltage is 120 V, while the generated EMF is 133 V. Determine: The generated EMF when the output is 2 kW at terminal voltage of 135 V. *

a.145.36 v

b.142.64 v

c.139.26 v

d.140.68 v