Free download pdf Andhra Pradesh Southern power Distribution Company Limited for Engineers APSPDCL Electrical Technical Last 10 Years Papers with solution, Last Year APSPDCL APSPDCL Electrical Technical Question Papers Answers 2011 pdf Model Papers APSPDCL Electrical Technical Solved

For V/F control, when frequency is increased in transformer

a) Core loss component current increases, Magnetizing component current decreases
b) Core loss component current increases, Magnetizing component current increases
c) Core loss component current decreases, Magnetizing component current decreases
d) Core loss component current decreases, Magnetizing component current increases

Ans: Core loss component current decreases, Magnetizing component current decreases

In ceiling fan the angle between auxiliary winding a main winding is

a) 0 deg
b) 90 deg
c) 180 deg
d) 360 deg

Ans: 90 deg

a) Field flux production
b)
c)
d)

Ans: Field flux production

Practical method of improving string efficiency

a) Increasing crass arms length
b) Using different size of insulators
c) Using different insulator materials
d) Using of guard rings

Ans: Increasing crass arms length*

In which type of fault all 3-phase components are equal

a) L-G
b) L-L
c) L-L-G
d) 3-Phase fault

Ans: 3-Phase fault

11/220 KV 100 MVA transformers, the primary base voltage rating is 10 KV then secondary base KV is

a) 10 KV
b) 220 KV
c) 220/sqrt3
d)

Ans: 220/sqrt3*

Water hamming effect is occurs in

a) Surge tank
b) Penstock
c) Turbine
d) Reservoir

Ans: Penstock

Transient stability can be improved by

a) By putting series capacitor
b) By using dynamic resister
c) Auto re-closers
d) All of the above

Ans: All of the above

If sending end voltage is Vs at no-load in a transmission line then receiving end voltage is if ABCD parameters of line is given

a) Vs
b) Vs/A
c) 0
d) Infinity

Ans: Vs/A

Harmonics are eliminated by using

a) Skewing of rotor
b) Distribution winding
c) Short pitch winding
d) All of the above

Ans: All of the above

For parallel operation of transformer at no load, then load shared are equal when

a) Impedance is proportional with respect to own KVA rating
b)
c)
d)

Ans: Impedance is proportional with respect to own KVA rating

In Induction motor Slip frequency of rotor current, when rotor speed is Nr. Then rotor producing slip field rotates with respect to stator is

a) Slip frequency
b) Nr
c) Ns
d) None

Ans: Ns

Good regulation means

b)
c)
d)

At dead short circuit at terminals of Alternator then the current I is

a) ZPF Lag
c) Unity power factor
d) 0.8 Power factor lag

Ans: ZPF Lag

Full scale Ammeter reading is 10 mA, Voltage across Ammeter is 100 mV. Then for 100 A measurements the power loss in the circuit is

a) 1 W
b) 10 W
c) 100 W
d) 1000 W

Ans: 10 W*

When Alternator excitation increases and machine is operating at lagging power factor then

a) I increase
b) I decreases
c) No effect on current
d) None

Ans: I increase

Flue gases coming out from furnace is first going through

a) Turbine
b) Economizer
c) Air pre-heater
d) Chimney

Ans: Economizer

Two alternators rated are 200 KW at 4% regulation, 400 KW 5% regulation operating in parallel at 50HZ , when supply 600 KW the new frequency is

a) 50
b) 49
c) 51.3
d) 47.7

Ans: 47.7

Va and Vb are negative sequence component voltages the difference angle between Va and Vb with respect to Va is

a) 240
b) 120
c) 180
d) 360

Ans: 120

4-Quadrent operation of chopper I is positive but V is may be positive are negative operates in which quadrant

a) 1 and 2
b) 2 and 3
c) 1 and 3
d) 1 and 4

Ans: 1 and 4

Heat convection, radiation, and conduction all are takes place in

a) Ice
b) Boiler
c) Refrigerator
d) Flue gases in pipe

Ans:

When moving iron meter is used to measure d.c current what is the disadvantage

a) It calibration in rms value
b)
c)
d)

Ans:

maximum power transfer to load is

a) 20 W
b) 50 W
c) 100W
d) 0W

Ans: 0W

Find Zbus Parameters

a) Z11=Z12=Z21= j0.1 ohm, Z22=j0.3 ohm
b)
c)
d)

Ans: Z11=Z12=Z21= j0.1 ohm, Z22=j0.3 ohm

Find Z11 and Z12

a) Z11=4 ohm, Z12= 2 ohm
b) Z11=4 ohm, Z12= 5 ohm
c) Z11=5 ohm, Z12= 2 ohm
d) Z11=4 ohm, Z12= 3 ohm

Ans:

Current in 5 ohm resister is

a) 10 A
b) -10 A
c) 5 A
d) -5 A

Ans: -10 A

I in the circuit at t=0+

a) 2 A
b) 5 A
c) 7 A
d) 10 A

Ans:

voltage across inductor at t=0+

a) 0 V
b) 2.5 V
c) 5 V
d) 10 V

Ans: 5 V

This wave is applied to the PMMC meter, meter reads

a) 0 V
b) 3 V
c) 2 V
d) 1 V

Ans: 1 V

Find Vab

a) Zero
b) 50 at an angle of 90 deg
c) 50 at an angle of 90 deg
d) None

Ans:

71. Find E in the circuit

a) 5 V
b) 10 V
c) 20 V
d) None

Ans: None

Vab is reference then angle between Vab and Ib is

a) -15 deg
b) 240 deg
c) 180 deg
d) -45 deg

Ans: -15 deg*

When maximum power transfer to load is
a) 20 W
b) 50 W
c) 100W
d) 0W
Ans: 0W

Find Zbus Parameters
a) Z11=Z12=Z21= j0.1 ohm, Z22=j0.3 ohm
b)
c)
d)
Ans: Z11=Z12=Z21= j0.1 ohm, Z22=j0.3 ohm

Find Z11 and Z12
a) Z11=4 ohm, Z12= 2 ohm
b) Z11=4 ohm, Z12= 5 ohm
c) Z11=5 ohm, Z12= 2 ohm
d) Z11=4 ohm, Z12= 3 ohm
Ans:

Current in 5 ohm resister is
a) 10 A
b) -10 A
c) 5 A
d) -5 A
Ans: -10 A

Find I in the circuit at t=0+
a) 2 A
b) 5 A
c) 7 A
d) 10 A
Ans: 2 A

Find voltage across inductor at t=0+
a) 0 V
b) 2.5 V
c) 5 V
d) 10 V
Ans: 5 V

This wave is applied to the PMMC meter, meter reads
a) 0 V
b) 3 V
c) 2 V
d) 1 V
Ans: 1 V

Find Vab
a) Zero
b) 50 at an angle of 90 deg
c) 50 at an angle of 90 deg
d) None
Ans:
Find E in the circuit
a) 5 V
b) 10 V
c) 20 V
d) None
Ans: None

Vab is reference then angle between Vab and Ib is