1. For an overhead line, the surge impedance is taken as (a) 20 – 40 ohm. (b) 70 – 80 ohms (c) 100 – 200 ohms (d) 500 -1000 ohms 2. The presence of ozone due to corona is harmful because it (a) reduces power factor (b) corrodes the material (c) transfer energy to the […]
1. ……………. are the conductors, which connect the consumer’s (a) terminals to the distribution (b) Distributors (c) Service mains (d) Feeders (e) None of the above 2. The underground system cannot be operated above (a) 440 V (b) 11 kV (c) 33 kV (d) 66 kV 3. The usual spans with R.C.C. poles are (a)
1. Which of the following statements regarding a reluctance motor is incorrect ? (a) It cannot be reversed, ordinarily. (b) It requires no D.C. field excitation for its operation. (c) It is nothing else but a single-phase, salient pole synchronous-induction motor. (d) Its squirrel cage rotor is of unsymmetrical magnetic construction in order to vary
1. Which of the following motors can be used for unity power factor ? (a) Capacitor run motor (b) Shaded pole motor (c) Hysteresis motor (d) Schrage motor 2. When a D.C. series motor is connected to A.C. supply, the power factor will be low because of (a) high inductance of field and armature circuits
1. In a split phase motor, the running winding should have (a) high resistance and low inductance (b) low resistance and high inductance (c) high resistance as well as high inductance (d) low resistance as well as low inductance 2. If the capacitor of a single-phase motor is short circuited (a) the motor will not
1. Reduction in core losses and increase in permeability are obtained with transformer employing (a) core built-up of laminations of cold rolled grain oriented steel (b) core built-up of laminations of hot rolled sheet (c) either of the above (d) none of the above 2.In a power or distribution transformer about 10 pm cent end
1. The reactance of a transformer depends on (a) size of the core (b) size of the tank (c) leakage flux (d) all of the above. 2. Which winding of the transformer has less cross-sectional area ? (a) Primary winding (b) Secondary winding (c) Low voltage winding (d) High voltage winding 3. Which of the
1.A voltage transformer of which class of accuracy can be used for precision testing in standard laboratories? (a) 0.1 class (b) 10 class (c) 5.00 class (d) 1000 class 2. In a transformer the tappings are generally provided on (a) primary side (b) secondary side (c) low voltage side (d) high voltage side 3. The
1. In a 50 kVA transformer the number of turns in the primary and secondary windings are 834 and 58 respectively. If the primary is connected to 3300 V supply the secondary current will be (a) 15 A (b) 30 A (c) 218 A (d) 238 A 2. If full load copper loss of a
1. In a power transformer (a) primary winding is closer to core (b) secondary winding is closer to core (c) low voltage winding is closer to core (d) high voltage winding is closer to core 2. In a transformer, the magnetic coupling between primary and secondary circuit can be increased by (a) increasing the number