APTRANSCO Electrical Sub Engineer Question Papers1.The Resistance of Armature Winding depends up on a) number of conductors b) length of conductor c) Cross sectional area of the onductor d) all of the above 2. The pole pitch of the four pole dc generator provided with a two layer lap winding with sixteen coils is a) 4 b)16 c)32 d)8 3. The thickness of lamination of dc machines is a)0.005 mm b)0.05mm c)0.5mm d)5mm 4. The purpose of providing dummy coils in the generator is a) to reduce eddy current losses b) to enhance flux density c) to amplify voltage d) to provide mechanical balance for the rotor 5. The material used for commutator brushes is a) copper b) mica c) carbon d) cast iron 6. For generating large currents on DC generators,which winding is generally preffered a) lap winding b) progressive winding c) retrogressive winding d) current depends on design 7. The direction of rotation of dc series motor can be changed by a) interchanging the supply coils b) interchanging field terminals c) a or b d) None 8. DC motor connected across AC supply results in a) Motor will burn b) Motor will run at rated speed c) Motor will run at corresponding synchronous speed d) Motor will run at slow speed 9. In Flemings left hand rule if the forefinger points in the direction of the field or flux,then the middle finger will point in the direction of a) Current in the conductor b) movement of conductor c) resultant force on conductor d) none 10.The synchronous speed of a motor with 6 poles and operating at 50 Hz frequency is a) 1500 b) 1000 c) 3000 d) 750 11) Which types of following motors are most efficient? a) TEFC b) SPDP c) Both d) None 12) What determines the thermal loading on the motor? a) Duty/Load cycle b) Temperature of the winding c) Age of the motor d) Ambient conditions 13) Unbalance in voltages at motor terminals is caused by ____. a) Supplying single phase loads disproportionately b) Use of different sizes of cables c) Both (a) & (b) d) None 14) Application of DC motors is generally restricted to a few load speed applications because of _____.
a) cost of the motor is high b) problems with mechanical commutation c) Maintenance problems d) None of the above 15) Which of the following information available on name plate of a motor? a) HP rating b) RPM c) Frame model d) all the above 16) The form factor for sinusoidal waveform is 1) 1.00 2) 1.11 3) 1.732 4) 2.2 17) The rotor resistance and reactance of a three-phase induction motor is 0.2 ohm and 2 ohm respectively. The per unit slip corresponding to maximum torque is equal to 1) 9.02 2) 0.01 3) 0.1 4) 0.2 18) Load factor is defined as the ratio of 1) Average power demand to maximum power demand 2) Minimum power demand to maximum power demand 3) Maximum power demand to minimum power demand 4) Average power demand to minimum power demand 19) The unit of luminous flux is 1) lux 2) candle power 3) metre cancle 4) lumen 20) For 132 KV transmission line, the insulators commonly used are 1) Strain type 2) Pint type 3) Suspension type 4) Shackle type 21) DC Transmission lines are free from a) Inductance b)Capacitance c) Phase Displacement d) All 22) DC Transmission lines are free from a) Skin Effect b) Corona Effect c) Resistance Drop d) All 23) Transmission efficiency increases as (A) voltage and power factor both increase (B) voltage and power factor both decrease (C) voltage increases but power factor decreases (D) voltage decreases but power factor increases
24) In overhead transmission lines the effect of capacitance can be neglected when the length of line is less than (A) 200 km (B) 160 km (C) 100 km (D) 80 km
25) The disadvantage of constant voltage transmission is (A) short circuit current of the system is increased (B) load power factor in heavy loads (C) large conductor area is required for same power transmission (D) air of the above
26)The current drawn by the line due to corona losses is (A) sinusoidal (B) square (C) non-sinusoidal (D) Triangular
27)Which distribution system is more reliable ? (A) Ring main system (B) Tree system (C) Radial system (D) All are equally reliable. 28) Step-up substations are associated with (A) distributors (B) consumer location (C) concentrated load (D) generating stations 29)A bus bar is rated by (A) current only (B) current and voltage only (C) current, voltage, frequency (D) current, voltage, frequency and short time current 30) Ina transformer the energy is conveyed from primary to secondary through a) air b) cooling oil c) flux d) none 31) The basic electrical Quantities are a) charge and voltage b)energy and current c)charge and energy d) voltage and current 32) For a DC voltage an inductor acts as a) open circuit b) short circuit c) finite resistance d) a voltage source 33) Apparent power is expressed in ……………… 34) A power factor of 1 indicates…………….. 35) The average value of a sine wave is……….. 36) The power factor of a circuit is equal to………. 37) The phase angle of a series RLC circuit at resonance is………………. 38) The efficiency of a thermal power plant improves with (A) increased quantity of coal burnt (B) larger quantity of water used (C) lower load in the plant (D) use of high steam pressures. More questions and model papers will be updated within a couple of hours…