13 views
in Transformer by
A 500 kVA, 3-phase transformer has iron losses of 300 W and full load copper losses of 600 W. The percentage load at which the transformer is expected to have maximum efficiency is 

(A) 50.0% (B) 70.7% (C) 141.4% (D) 200.0%

1 Answer

0 votes
by

A 500 kVA, 3-phase transformer has iron losses of 300 W and full load copper losses of 600 W. The percentage load at which the transformer is expected to have maximum efficiency is 70.7%

Related questions

1 answer 28 views

 A transformer has maximum efficiency at 3/4 full load. The ratio of its iron losses and full load copper loss is : -  a) 16/9 b) 4 / 3 c) 3/4 d) 9 /16

asked Apr 11, 2018 in Electrical Engineering by Shimroz123
1 answer 52 views

A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The proportion of full load at maximum efficiency is

asked May 8, 2018 in Electric Power Transmission by Shimroz123
1 answer 17 views

A single-phase, 50 kVA, 250 V/500 V two winding transformer has an efficiency of 95% at full load, unity power factor. If it is re-configured as a 500 V/750 V auto-transformer, its efficiency at its new rated load at unity power factor will be  (A) 95.752% (B) 97.851% (C) 98.276% (D) 99.241%

asked May 17, 2018 in Transformer by Shimroz123
1 answer 41 views

At full -load of a transformer, the iron loss and copper loss are 3000 W and 4000 W respectively. Then total loss at maximum efficiency is :  (A) 7000 W (B) 6000 W (C) 8000 W (D) 4000 W

asked Apr 30, 2018 in Electrical Engineering by Shimroz123
0 answers 14 views

One 200 KVA transformer has an iron loss of 1 KW and full load Cu loss of 2 KW. Its load KVA corresponding to maximum efficiency is:  (A) 100 KVA (B) 141.4 KVA (C) 50 KVA (D) 200 KVA 

asked Apr 5, 2018 in Electrical Engineering by Shimroz123
1 answer 17 views

A simple phase transformer has a maximum efficiency of 90% at full load and unity power factor. Efficiency at half load at the same power factor is  (A) 86.7% (B) 88.26% (C) 88.9% (D) 87.8%

asked May 17, 2018 in Transformer by Shimroz123
1 answer 25 views

A single-phase transformer has no-load loss of 64 W, as obtained from an open circuit test. When a short-circuit test is performed on it with 90% of the rated currents flowing in its both LV and HV windings, he measured loss is 81 W. The transformer has maximum efficiency when operated at  (A) 50.0% of the rated current (B) 64.0% of the rated current (C) 80.0% of the rated current (D) 88.8% of the rated current

asked May 17, 2018 in Transformer by Shimroz123
0 answers 24 views

A single phase 230 V/ 150 V , 1 kVA, 50 Hz transformer is supplied by 230 V AC supply. Find the full load primary and secondary current. 

asked Sep 1, 2018 by Quiz
1 answer 21 views

Full load copper loss in a transformer is 1600 watts. At half load the copper loss will be: A) 6400 watt B) 1600 watt C) 800 watt D) 400 watt

asked Jun 4, 2018 in Transformer by Shimroz123
1 answer 20 views

A single-phase ac voltage source has 200 V rms and a system connected consumes an active power of 300 W. What is the reactive power consumed by the system if 2.5 A rms current is drawn ?  (a) 100 VAR (b) 200 VAR (c) 300 VAR (d) 400 VAR

asked Apr 23, 2018 in Electrical Engineering by Zeeshan
1 answer 24 views

A single-phase transformer has a turns ratio of 1 :2 and is connected to a purely resistive load as shown in the figure. The magnetizing current drawn is 1A, and the secondary current is 1A. Ifcore losses and leakage reactances are neglected, the primary current is  A)1.41A B)2A C) 2.24A D)3A

asked May 20, 2018 in Transformer by Shimroz123
0 answers 11 views

A 3-phase, 50 Hz, 500 V induction motor develops 20 hp at slip of 5%. Mechanical losses are 1 hp, and stator loss is 1 kW. The efficiency will be   (a) 95.3% (b) 90.5% (c) 91.3% (d) 85.3% 

asked Apr 10, 2018 in Electrical Engineering by Shimroz123
1 answer 28 views

A two -winding single phase transformer has a voltage regulation of 4.5% at full - load and unity power -factor. At full -load and 0.80 lagging power-factor, the voltage regulation will be: (A) 4.5% (B) less than 4.5% (C) more than 4.5% (D) none of the above

asked Apr 11, 2018 in Electrical Engineering by Shimroz123
1 answer 21 views

A 400kW, 3 -phase, 440V, 50Hz induction motor has a speed of 950 rpm on full load. The machine has 6 poles. The value of slip for the machine will be (A) 0.06 (B) 0.10 (C) 0.04 (D) 0.05

asked Apr 11, 2018 in Computer Engineering by Shimroz123
0 answers 15 views

A 50 Hz, 3—phase induction motor has a full load speed of 1440 rpm. The number of poles of the motor is:   (A)4 (8)6 (0)12  (D)8

asked Apr 9, 2018 in Electrical Engineering by Shimroz123
1 answer 41 views

The hysteresis and eddy current losses of a single phase transformer working on 200 V, 50 Hz supply are Ph and Pe respectively. The percentage decrease in these when operated on a 160 V, 40 Hz supply are   (a) 32, 36 (b) 20, 36 (c) 25, 50 (d) 40, 80 

asked May 13, 2018 in Transformer by Shimroz123
1 answer 20 views

Auto-transformer makes effective saving on copper and copper losses, when its transformation ratio is?

asked Mar 19, 2018 in Transformer by Shimroz123
1 answer 40 views

A 4000 kVA, 11 kV/132 kV delta-star connected 3-phase transformer has reactance, x1 = 0.12 p.u. The actual value of x1 referred to the low voltage side is (A) 0.85 Ω (B) 3.63 Ω (C) 36.3 Ω (D) 252 Ω

asked Apr 28, 2018 in Power system by Shimroz123
1 answer 37 views

A 150 kW electric motor has an efficiency of 92 %, when it operates at full load. Calculate the losses in the machine.  (A) 92 kW (B) 150 kW (C) 163 kW (D) 13 kW 

asked Apr 5, 2018 in Electrical Engineering by Shimroz123
1 answer 26 views

A 500 MW, 3-phase, Y-connected synchronous generator has a rated voltage of 21.5 kV at 0.85 p.f. The line current when operating at full load rated conditions will be  (A) 13.43 kA (B) 15.79 kA (C) 23.25 kA (D) 27.36 kA

asked May 17, 2018 in Synchronous machine by Shimroz123
0 answers 15 views

A 3-phase, 2 pole, 11 kV, 10000 kVA alternator has earthed neutral through a resistance of 7.0Ω. The machine has current balance protection which operates if out of balance current exceeds 20% of full load. Determine %age of winding protected against earth fault (1) 10.6% (2) 11.6% (3) 10.9% (4) 11.2% 

asked Apr 11, 2018 in Electrical Engineering by Shimroz123
1 answer 16 views

When two transformer of different kVA rating are connected in parallel they share the load in proportion to their respective kVA rating only when their:

asked May 22, 2018 in Transformer by Shimroz123
1 answer 15 views

In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?

asked Mar 19, 2018 in Transformer by Shimroz123
0 answers 32 views

 AM transmitter has a carrier power of 30 W. The percentage of modulation is 85%. Calculate the total power : (A) 5.4 W (B) 40.8 W (C) 10.8 W (D) 20.4 W

asked Apr 14, 2018 in Electrical Engineering by Shimroz123
1 answer 200 views

A 400/200 volts transformer has pu impedance of 0.05. The HV side voltage required to circulate full load current during short circuit test is

asked Apr 25, 2018 in Electrical Engineering by Shimroz123
1 answer 4 views

Which losses in a transformer varies significantly with load  a. Hysteresis losses b. Eddy current losses c. Copper losses d. Core losses 

asked May 17, 2018 in Transformer by Shimroz123
0 answers 108 views

A single phase transformer rated at 3000 kVA, 69 kV 4.16 kV, 60 Hz has a total internal impedance Zp of 127 ohm, referred to the primary side. Calculate the primary current if the secondary is accidentally short circuited.  (A) 43.5 A (B) 543 A (C) 9006 A (D) 721 A 

asked Apr 5, 2018 in Electrical Engineering by Shimroz123
1 answer 20 views

A moving coil instrument has a resistance of 10 W and gives full scale deflection when carrying a current of 50 mA. To measure current upto 100 A, we will have to connect • 10 W resistance in series • 10 W resistance in parallel • 10/1999 W resistance in series • 10/1999 W resistance in parallel

asked May 13, 2018 in Electrical Measurements and Instrumentation by Shimroz123
2 answers 73 views

 The no-load current drawn by transformer is usually what per cent of the full-load current ?

asked Mar 27, 2018 in Transformer by Shimroz123
0 answers 31 views

A single phase energy meter has a constant of 1200 revolution/kWh. When a load of 200 W is connected, the disc rotates at 4.2 revolutions per min. If the load is on for 10 hours, the meter records an excess of   (a) 0.1 kWh (b) 0.2 kWh (c) 1.0 kWh (d) 2.0 kWh 

asked Apr 10, 2018 in Electrical Engineering by Shimroz123
0 answers 16 views

A 1:5 step-up transformer has 120V across the primary and 600 ohms resistance across the secondary. Assuming 100% efficiency, the primary current will be:  (A) 0.2 Amp. (B) 5 Amps. (C)10 Amps. (D) 20 Amps

asked Apr 9, 2018 in Electrical Engineering by Shimroz123
1 answer 23 views

The analog signal given below is sampled by 600 samples per second for m(t) = 3 sin 500 pt + 2 sin 700 pt then folding frequency is: (1) 500 Hz (2) 700 Hz (3) 300 Hz (4) 1400 Hz 

asked May 28, 2018 in Analog electronics circuits by Shimroz123
0 answers 23 views

The constant of a given energy meter is 500 revolution/kWh. At the test 4.4 kW full load, meter completes 50 revolutions in 86 seconds. The percentage error of the meter is (a) –4.86% (b) 4.86% (c) 2.0% (d) 3.0%

asked May 26, 2018 in Electrical Measurements and Instrumentation by Shimroz123
1 answer 16 views

In a transformer, zero voltage regulation at full load is   (a)Not possible   (b) Possible at unity power factor load   (c) Possible at leading power factor load   (d) Possible at lagging power factor load

asked May 13, 2018 in Transformer by Shimroz123
1 answer 27 views

The total power of an AM transmitter having a carrier power of 50 W and the percentage of modulation at 80% is A) 50 W B) 66 W C) 68 W D) 70 W 

asked Jun 18, 2018 in Electronics Engineering by Shimroz123
0 answers 20 views

One 200 V, 100 W bulb is connected in series with primary of a 200 V, 10 kVA transformer. If its secondary is kept open circuited, then the bulb would have (1) Full brightness (2) Poor brightness (3) A little less than full brightness (4) More than full brightness 

asked Apr 11, 2018 in Electrical Engineering by Shimroz123
1 answer 21 views

What should be kVA rating of each transformer in V-V bank when three phase balanced load is 40 kVA ? (A) 19 (B) 28 (C) 37 (D) 23

asked May 13, 2018 in Electrical Engineering by Shimroz123
1 answer 11 views

The power consumed by a coil is 300 W when connected to a 30 V dc source and 108 W when connected to a 30 V ac source. The reactance of the coil is

asked Apr 23, 2018 in Electrical Engineering by Zeeshan
1 answer 34 views

Two coils connected in series have resistance of 600 ohm and 300 ohm and temperature coefficients of 0.1% and 0.4% respectively.The resistance of the combination at 50oC will be 

asked Mar 31, 2018 in Electrical Engineering by Shimroz123
1 answer 10 views
1 answer 29 views

An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is (A) 5.06 kW (B) 0.3 kW (C) 100 kW (D) 83.33 kW

asked Apr 28, 2018 in Electrical Machine by Shimroz123
1 answer 21 views

Two single-phase 150 kVA, 7200/ 600 volt transformers are connected in open-delta. The maximum three-phase load that they can carry is: A) 300 kVA B) 75 kVA C) 259 kVA D) 249 kVA

asked Jun 4, 2018 in Single phase transformer by Shimroz123
1 answer 22 views

The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be :  (A) 34.64 kVA (B) 75 kVA (C) 20 kVA (D) None of the above

asked May 8, 2018 in Electrical Engineering by Shimroz123
1 answer 18 views

A moving coil meter has a resistance of 3 Ω and gives full scale deflection with 30 mA. To measure voltage up to 300 V, the external resistance to be connected in series with the instrument is (A) 9997 Ω (B) 10000 Ω (C) 997 Ω (D) 10003 Ω

asked Apr 28, 2018 in Power Electronic Controlled Drives by Shimroz123
0 answers 22 views

Calculate the approximate locked rotor current of a 3 phase induction motor having a rating of 500 Hp, 2300 V.  (A) 130 A (B) 39 A (C) 390 A (D) 780 A 

asked Apr 5, 2018 in Electrical Engineering by Shimroz123
1 answer 137 views

A 3-phase, 11 kv, 50 Hz, 200 kW load has a power factor of 0.8 lag. A delta connected 3-phase capacitor is used to improve the power factor to unity. The capacitance perphase of the capacitor in micro-farads is?

asked Mar 27, 2018 in Power system by Shimroz123

Welcome to electronics2electrical.com here you can ask questions related to electrical, electronics, mechanical, telecommunication, instrumentation, computer, mathematics, physics etc.
Be respectful to all the members. Do not copy and paste the answers from other websites which have copyright content. While asking question give full details about it.

Categories

Most popular tags

power motor dc circuit transformer voltage current used system phase resistance factor synchronous load ac energy induction electric generator series frequency between speed capacitor use electrical meter line difference control type mosfet transmission magnetic plant high single instrument bjt unit source advantages function diode and machine winding field define torque parallel amplifier supply shunt thyristor motors electricity arduino maximum time relay armature problem value on transformers types coil diagram state flow ratio material three formula starting direction theorem method emf operating efficiency digital wave microprocessor test instruments inductance loss measure operation connected signal low applications effect single-phase network temperature working constant losses different law wattmeter measuring compare controlled breaker drive device logic rc full switch flux wire resistivity disadvantages free of materials machines angle force converter conductor transistor gain open protection scr core measurement number bridge principle generators reactance circuits negative the friction iron loop short pole battery conservation steam resistors hysteresis computer using analog lines secondary station gate a rectifier inverter linear induced relays nuclear capacitance basic characteristics design direct work rotor electronics ammeter forces diesel damping rlc connection factors capacitors minimum insulation moving regulation running self systems air fault range main stability quality starter igbt eddy alternator ideal rl average 3-phase plants arc thermal error fuzzy biasing dielectric pressure balanced superposition errors copper rotation feedback impedance measured electronic electrons charge inductive transfer explain start off back curve over solar is three-phase tariff locomotive peak bias zener engineering commutator surge conductors rating universal potentiometer density permanent mechanical transducer capacity memory adc excitation two fuse pure harmonics application semiconductor inductor internal pmmc reaction welding resonance traction permeability breakers rms designed electromagnetic si generation brushes switching capacitive shaded rate 1 distribution resistor methods delta star oscillator reluctance simplification algebra 8085 boolean weston dynamometer insulating strength installation definition fuel heating earth units
...