Electrical Transformer Multiple choice Question (Electrical Mcqs) and Answer Part 8
Electrical Engineering Objective Question and Answer
141- The power factor at which the regulation will be maximum is?
(A) 0.385 leading
(B) 0.615 leading
(C) 0.385 lagging
(D) 0.615 lagging
Answer: (C)
142- The maximum of this transformer will be ?
Answer: (C)
142- The maximum of this transformer will be ?
(A) 0.5%
(B) 2.5%
(C) 4.5%
(D) 6.5%
Answer: (D)
143- A 480/120 V . 5 k VA two winding transformer is to be used as an auto transformer to supply power at 480 V from 600 V source. The k VA capacity as auto transformer will be
Answer: (D)
143- A 480/120 V . 5 k VA two winding transformer is to be used as an auto transformer to supply power at 480 V from 600 V source. The k VA capacity as auto transformer will be
(A) 10 k VA
(B) 15 k VA
(C) 20 k VA
(D) 25 k VA
Answer: (D)
A 3-phase step down transformer is connected to 6.6 kV mains and takes 10 A. The ratio of turns per phase is 12 and losses may be neglected (Q 144-147)
144- The secondary line voltage will be least for which of the following connections?
Answer: (D)
A 3-phase step down transformer is connected to 6.6 kV mains and takes 10 A. The ratio of turns per phase is 12 and losses may be neglected (Q 144-147)
144- The secondary line voltage will be least for which of the following connections?
(A) Delta-delta
(B) star-star
(C) Delta-delta
(D) star-star
Answer: (D)
145- The secondary line voltage will be identical for which of the following two connections?
Answer: (D)
145- The secondary line voltage will be identical for which of the following two connections?
(A) Δ/Δ and Y/Y
(B) Y/Δ and Δ/Y
(C) Y/Y and Δ/Y
(D) Δ/Y and Δ/Δ
Answer: (A)
146- The secondary line current will be maximum for which of the following connections?
Answer: (A)
146- The secondary line current will be maximum for which of the following connections?
(A) Delta-delta
(B) Delta-star
(C) Star-star
(D) Star-delta
Answer: (B)
147- The secondary line current will be maximum for which of the following connections?
(D) Star-delta
Answer: (D)
148- Three 1100/110 V transformers connected. delta/delta supplying a lightning load of 100 kW , what current in secondary will be flowing in each transformer?
(D) 153 A
Answer: (A)
149- Two single phase transformers with equal turns have impedance of ( 0.5 + j 0.3 ) ohms and ( 0.6 + j 10 ) ohms with respect to the secondary. if they operate in parallel , how they will share a load of 100 kW at 0.8 p.f. lagging?
(D) 85.5 kW , 14.5 kW
Answer: (C)
A load of 800 kW at 0.8 lagging p.f. is supplied by two 3 phase transformers rated 400 kVA and 600 kVA operating in parallel. The transformer have the same turn ratio and their per unit resistance and reactance are given as (Q 150-154)
resistance reactances
400 kVA transformer 0.02 0.04
600 kVA transformer 0.01 0.05
150- The load shared 400 kVA transformer will be
Answer: (B)
147- The secondary line current will be maximum for which of the following connections?
(A) Delta-delta
(B) Delta-delta
(C) Star-star
Answer: (D)
148- Three 1100/110 V transformers connected. delta/delta supplying a lightning load of 100 kW , what current in secondary will be flowing in each transformer?
(A) 303 A
(B) 255 A
(C) 203 A
Answer: (A)
149- Two single phase transformers with equal turns have impedance of ( 0.5 + j 0.3 ) ohms and ( 0.6 + j 10 ) ohms with respect to the secondary. if they operate in parallel , how they will share a load of 100 kW at 0.8 p.f. lagging?
(A) 50 kW , 50 kW
(B) 62 kW , 38kW
(C) 78.2 kW , 21.8 kW
Answer: (C)
A load of 800 kW at 0.8 lagging p.f. is supplied by two 3 phase transformers rated 400 kVA and 600 kVA operating in parallel. The transformer have the same turn ratio and their per unit resistance and reactance are given as (Q 150-154)
resistance reactances
400 kVA transformer 0.02 0.04
600 kVA transformer 0.01 0.05
150- The load shared 400 kVA transformer will be
(A) 234 kVA
(B) 325 kVA
(C) 456 kVA
(D) 525 kVA
Answer: (C)
151- The load shared by 600 k VA transformer will be
Answer: (C)
151- The load shared by 600 k VA transformer will be
(A) 546 k VA
(B) 456 k VA
(C) 412 k VA
(D)388 k VA
Answer: (A)
152- Power factor of 600 k VA transformer will be
Answer: (A)
152- Power factor of 600 k VA transformer will be
(A) 0.882 lagging
(B) 0.725 lagging
(C) 0.625 leading
(D) 0.182 leading
Answer: (A)
153- Power factor of 600 k VA transformer will be
Answer: (A)
153- Power factor of 600 k VA transformer will be
(A) 0.882 lagging
(B) 0.725 lagging
(C) 0.625 leading
(D) 0.182 leading
Answer: (B)
154- The percentage regulation of 4800/240 volt distribution transformer is 3.33 percent. The voltage to which the secondary voltage will rise when full load is removed , will be
Answer: (B)
154- The percentage regulation of 4800/240 volt distribution transformer is 3.33 percent. The voltage to which the secondary voltage will rise when full load is removed , will be
(A) 240 V
(B) 232 V
(C) 248 V
(D) 320 V
Answer: (C)
155- The core loss when the transformer is connected to 4400 Volt 50 Hz source will be
Answer: (C)
155- The core loss when the transformer is connected to 4400 Volt 50 Hz source will be
(A) 306 W
(B) 600 W
(C) 904 W
(D) 1004 W
Answer: (C)
156- The Core loss when transformer is connected to 4600 volt , 60 Hz source will be
Answer: (C)
156- The Core loss when transformer is connected to 4600 volt , 60 Hz source will be
(A) 907 W
(B) 875 W
(C) 603 W
(D) 306 W
Answer: (A)
157- Impedance matching transformer are used for
(D) minimizing the effect of harmonics
Answer: (A)
158- The transformed power will be
Answer: (A)
157- Impedance matching transformer are used for
(A) measuring low voltages and low currents
(B) measuring high voltages and high currents
(C) stabilizing voltage fluctuations due to varying load
Answer: (A)
158- The transformed power will be
(A) 620 W
(B) 1240 W
(C) 2480 W
(D) 2760 W
Answer: (B)
159- The power conducted directly from the source to the load will be
Answer: (B)
159- The power conducted directly from the source to the load will be
(A) 1240 W
(B) 2000 W
(C) 2760 W
(D) 3000 W
Answer: (C)
Following two transformer are connected in parallel and deliver a total load of 300 kVA.
Transformer 1 Transformer 2
Rating = 150 kVA Rating = 250 kVA
6900/230 volts 6900/230 volts
Ze= 9.4 in primary terms Ze = 5.8 in primary terms
160- The load current will be
Answer: (C)
Following two transformer are connected in parallel and deliver a total load of 300 kVA.
Transformer 1 Transformer 2
Rating = 150 kVA Rating = 250 kVA
6900/230 volts 6900/230 volts
Ze= 9.4 in primary terms Ze = 5.8 in primary terms
160- The load current will be
(A) 100 A
(B) 87 A
(C) 43.5 A
(D) 25 A
Answer: (C)
Answer: (C)
Please someone show the detailed solution of Q144-147. Please someone send the answer to me as fast as possible. Tommorow is my exam.
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