Each question carries 1 mark.
Negative marking: 1/4 mark
Total Questions: 6
Time: 6 min.
Q1. Pole mounted substations are used in
(a) Primary distribution system
(b) Secondary distribution system
(c) Primary transmission system
(d) Secondary transmission system
Q2. Under running conditions, the maximum torque of 3-phase induction motor will
occur at that value of slip at which rotor resistance/phase is ……. rotor reactance/phase.
(a) two times
(b) four times
(c) equal to
(d) none of the above
Q3. An 8-pole alternator runs at 750 r.p.m. and supplies power to a 6-pole induction
motor which has a full-load slip of 3%. The full-load speed of the motor is
(a) 1050 r.p.m.
(b) 970 r.p.m.
(c) 960 r.p.m.
(d) 1250 r.p.m.
Q4. The two-part tariff is used for…………consumers.
Q5. A MOSFET has………terminals.
Q6. The impedance of a circuit is given by Z = 3 + j4. its conductance will be:
Sol. Pole mounted substations:
Used in secondary distribution system.
It is an outdoor substation with equipment installed overhead on H-type or 4-pole structure.
The voltage rating of transformers in a pole mounted substations is 11 KV/400 V.
S2. Ans. (c)
Sol. The developed torque is maximum when the rotor resistance per phase is equal to the rotor reactance per phase under running conditions.
Sol. An 8-pole alternator runs at 750 r.p.m. and supplies power to induction
Speed of stator flux of induction motor
= 1000 rpm
Sol. The two-part tariff is used for industrial consumers. In the two-part tariff, there are fixed charge and running charge which depends on maximum demand and total consumed electrical energy respectively.
Sol. Schematic symbol of n-channel MOSFET: