Define the percentage voltage regulation and efficiency of a power transformer.  

1 Answer

Answer :

Voltage regulation is the difference between no load voltage and full load voltage by no load voltage.

Voltage regulation = No load voltage – Full load voltage / No load voltage.

Voltage regulation is mentioned in % (percentage).

% Voltage regulation = No load voltage – Full load voltage * 100 / No load voltage.

Efficiency of a transformer is the ratio of output in watts and input in watts.

Efficiency = Output in watts / Input in watts.

% Efficiency = Output in watts * 100 / Input in watts.

% Efficiency = Output in watts * 100 / Output in watts + losses. 


Related questions

Description : What are the necessary tests to determine the efficiency, voltage regulation, and temperature rise of winding & insulation of transformer?

Last Answer : 1.Direct loading test 2.Open circuit test 3. Short circuit test 4. Sumpner's or back to back test

Description : Define: (i) Efficiency (ii) Voltage regulation of transformer.

Last Answer : i) Efficiency : It is the ratio of output power to the input power of the transformer.It is denoted by η. ii) Voltage Regulation of transformer: The ratio of the change in Secondary Terminal ... So where, VNL = No Load Secondary voltage VFL = Full load secondary voltage

Description : A transformer has negative voltage regulation when its load power factor is- (a) Zero (b) Unity (c) Leading (d) Lagging

Last Answer : Ans: C

Description : 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 power-factor lagging load the voltage regulation will be (A) 4.5%. (B) less than 4.5%. (C) more than 4.5%. (D) 4.5% or more than 4.5%.

Last Answer : (C) more than 4.5%.

Description : In a transformer, with closed magnetic coupling between primary and secondary __ will improve: a) Efficiency b) All day efficiency c) Regulation d) None of the above

Last Answer : Ans: C

Description : In a transformer the voltage regulation will be zero when it operates at (A) unity p.f. (B) leading p.f. (C) lagging p.f. (D) zero p.f. leading.

Last Answer : (B) leading p.f.

Description : State the effects of low power factor on efficiency and voltage regulation of short transmission lines. 

Last Answer : i) Effect of Low power factor on efficiency:- When power factor of load reduces current drawn by transmission line increases so copper losses in transmission line increases, hence transmission ... increases, so voltage drop in transmission line increases so regulation increases. (Become Poor) 

Description : 51 A transformer has negative voltage regulation when its load power factor is A. Zero B. Unity C. Leading D. Lagging

Last Answer : C. leading

Description : A transformer has negative voltage regulation when its load power factor is   (1) Zero (2) Unity (3) Leading (4) Lagging

Last Answer : 0

Description : 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

Last Answer : 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: more than 4.5%

Description : Define the term voltage regulation of Alternator.

Last Answer : The voltage regulation of an Alternator is defined as the change in terminal voltage from no-load to load condition expressed as a fraction or percentage of terminal voltage at load condition ; the speed and excitation conditions remaining same.

Description : Define following parameter of rectifier: (i) Ripple factor (ii) Efficiency (iii) Peak Inverse Voltage (iv) Transformer utilization factor

Last Answer : (i) Ripple Factor - Ripple factor (γ) may be defined as the ratio of the root mean square (rms) value of the ripple voltage to the absolute value of the DC component of the ... the same rectifier. Effective VA Rating of transformer is the average of primary and secondary VA rating of transformer.

Description : Define all day efficiency of a transformer?

Last Answer : A:It is computed on the basis of energy consumed during a certain period, usually a day of 24 hrs. All day efficiency=output in kWh/input in kWh for 24 hrs.

Description : Define efficiency of the transformer?

Last Answer : Transformer efficiency ƞ= (output power/input power) x 100

Description : A resistor placed in parallel to the output of a power supply _____________. A. is a temperature compensator B. corrects power factor C. prevents excessive currents D. aids in output voltage regulation

Last Answer : Answer: D

Description : State and justify which of the following two transformers is better:  Transformer A = 4% voltage regulation  Transformer B = 6% voltage regulation

Last Answer : Transformer A with 4% voltage regulation is better.  Justification: Voltage regulation refers to the percentage change in secondary voltage when load is changed from no-load to full-load with primary voltage ... 4% voltage regulation, which is less as compared to 6% of transformer B, it is better.

Description : In a transformer the voltage regulation will be zero when it operates at (A) unity p.f. (B) leading p.f. (C) lagging p.f. D) zero p.f. leading.

Last Answer : In a transformer the voltage regulation will be zero when it operates at leading p.f.

Description : 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

Last Answer : In a transformer, zero voltage regulation at full load is Possible at leading power factor load 

Description : A good voltage regulation of a transformer means?

Last Answer : A good voltage regulation of a transformer means output voltage fluctuation from no load to full load is least.

Description : What is Meant by Regulation in a Transformer?

Last Answer : ANSWER: Voltage regulation in transformers is the difference between the no load voltage and the full load voltage. This is usually expressed in terms of percentage. For example: A transformer delivers 100 ... from 2% to 4%, depending on the size and the application for which they are used

Description : What is meant by regulation in a transformer?

Last Answer : A. Voltage regulation in transformers is the difference between the no load voltage and the full load voltage. This is usually expressed in terms of percentage. Example: A Transformer delivers 100 ... The regulation capacity varies depending on the size and the application for which they are used.

Description : What is Meant by Regulation in a Transformer?

Last Answer : Voltage regulation in transformers is the difference between the no load voltage and the full load voltage. This is usually expressed in terms of percentage. For example: A transformer delivers 100 volts ... voltage drop in transformer/ no load voltage of transformer V2>E2 for leading p.f load V2

Description : Percentage voltage regulation = _______________________ x 100 ; (Where VNL=No Load Voltage, VFL=Full Load Voltage)

Last Answer : Percentage voltage regulation = _______________________ x 100 ; (Where VNL=No Load Voltage, VFL=Full Load Voltage) (VNL-VFL)/VFL or (VNL-VFL )/VNL

Description : At what power maximum efficiency of power transformer and distribution transformer is designed

Last Answer : Maximum efficiency of the transformer is attained at certain load factor (α) when core losses of transformer is equal to the copper losses. PCore loss = α ^2 X PCopper loss From the ... the day. Hence distribution transformers are designed to have maximum efficiency at 50% of the rated full load

Description : Which of the following statements is true regarding the illustrated circuit? El-0069 A. This full wave bridge should never be used aboard ship because the ground on lead 'A' will show on ... be direct current suitable for electronic circuits requiring voltage regulation. D. All the above are true.

Last Answer : Answer: B

Description : The instantaneous reduction in voltage of an AC generator, resulting from an increase in load, and prior to the automatic voltage regulator correcting the situation, is called voltage ____________. A. droop B. drop C. dip D. regulation

Last Answer : Answer: C

Description : Autotransformer starters or compensators are sometimes used with polyphase induction motors to _____________. A. reduce the voltage applied to the motor during the starting period B. increase the voltage for ' ... to be either stepped up or down, depending on the application, to ensure full torque

Last Answer : Answer: A

Description : Why is the MMF method of estimating the voltage regulation considered as the optimistic method?

Last Answer : In this method the actual value is more than the result obtained.

Description : What are the test data required for predetermining the voltage regulation of an Alternator by MMF method?

Last Answer : Data required for MMF method are : · Effective resistance per phase of the 3-phase winding R · Open circuit characteristic (OCC) at rated speed/frequency · Short circuit characteristic (SCC) at rated speed/frequency

Description : Why is the synchronous impedance method of estimating voltage regulation considered as pessimistic method?

Last Answer : Compared to other methods, the value of voltage regulation obtained by the synchronous impedance method is always higher than the actual valuei.e actual value is lower than the results obtained and therefore this method is called the pessimistic method.

Description : What are the advantages and disadvantages of estimating the voltage regulation of an Alternator by EMF method?

Last Answer : Advantages: · Simple no load tests (for obtaining OCC and SCC) are to be conducted · Calculation procedure is much simpler Disadvantages: · The value of voltage regulation obtained by this method is always higher than the actual value

Description : Name the various methods for predetermining the voltage regulation of 3-phase Alternator.

Last Answer : The following are the three methods which are used to predetermine the voltage regulation of smooth cylindrical type Alternators · Synchronous impedance / EMF method · Ampere-turn / MMF method · Potier / ZPF method

Description : What is the necessity for predetermination of voltage regulation?

Last Answer : Most of the Alternators are manufactured with large power rating , hundreds of kW or MW, and also with large voltage rating upto 33kV. For Alternators of such power and voltage ratings ... performance like voltage regulation then can be predetermined at any desired load currents and power factors.

Description : What are the factors affecting voltage regulation?

Last Answer : Load current Equivalent resistance Equivalent reactance power factor

Description : What is the condition for maximum voltage regulation?

Last Answer : It occurs when load is inductive and power factor is lagging.

Description : What is the condition for zero voltage regulation?

Last Answer : Negative sign indicates zero voltage regulation. It occurs when load is capacitive and power factor is leading.

Description : What is the efficiency percentage of a transformer ?

Last Answer : No machine has ever been discovered in the world with 100% efficiency or output. The only transformer is a device whose output power is about 90% to 99% of the input. This means that the power loss ... to the input and output of a device by which the efficiency of the device can be measured.

Description : Transmission efficiency of transmission line increases with the: a) Decrease in power factor and voltage b) Increases in power factor and voltage c) Increase in power factor and decrease in voltage d) Increase in the voltage but decrease in the power factor

Last Answer : Ans: B

Description : The harmonic currents in a power transformer does not cause increase in: a) Secondary voltage b) Core loss c) Copper loss d) Magnetic interference with protective relays

Last Answer : Ans: A

Description : Which of the following statements is true concerning a stepdown transformer in an operating AC power circuit? A. Voltage and current will both be increased. B. Voltage and current will both be decreased C. Voltage decreases as current increases. D. Voltage increases as current decreases.

Last Answer : Answer: C

Description : A transformer in an electric circuit serves to ____________. A. generate its own electrical power B. transform electrical energy into mechanical energy C. increase or decrease circuit voltage as required D. convert AC current to DC current

Last Answer : Answer: C

Description : The function of a stepdown potential transformer is to reduce the load _____________. A. voltage and current B. voltage and increase line current C. current and increase line voltage D. power

Last Answer : Answer: B

Description : Why the efficiency of the Induction motor is less compared to transformer?

Last Answer : Answer: Induction motor and Transformer operates on the same principle that power is transferred to secondary by mutual induction. But in transformer, flux will be traveled from primary to ... compared to transformer which also results in less efficiency for induction motor compared to transformer.

Description : Why Is The Efficiency Of A Three-phase Induction Motor Is Less Than That Of A Three-phase transformer ?

Last Answer : Three phase Induction motor is nothing but a rotating transformer . Due to rotating nature, there are friction and windage losses associated with it. On the other hand, the three-phase transformer is ... the efficiency of three-phase induction motor is less than that of a three-phase transformer .

Description : What is the condition for maximum efficiency of transformer?

Last Answer : When Iron losses is equal to copper losses.

Description : Why the efficiency of distribution transformer is 60 to 70 % and not 100%?

Last Answer : Distribution transformer is designed for maximum efficiency at 60% to 70% load as it normally doesn't operate at full load all the time. Its load depends on distribution demand. Whereas power transformer ... efficiency at 100% load as it always runs at 100% load being near to generating station.

Description : The efficiency of a transformer is mainly dependent on (A) core losses. (B) copper losses. (C) stray losses. (D) dielectric losses.

Last Answer : Ans: A Core loss has prominent value over other losses

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

Last Answer : I1= V1 /R1 = 120/600 = 0.2 (η = 100%, losses are zero ∴V1 = VR = I1R1)

Description : Define the term related to power amplifier. (i) Efficiency (ii) Voltage gain

Last Answer : (i) Efficiency: Efficiency of the power amplifier is defined as the ratio of maximum a.c. output power to the d.c. input power. Mathematically (ii) Voltage gain: Voltage gain of the power amplifier is defined as the ratio of output voltage to the input voltage. Mathematically,

Description : Define: (i) Commercial efficiency of a transformer and  (ii) All day efficiency of a transformer.

Last Answer : (i) Commercial Efficiency : It is the ratio of output power in watt to the input power in watt. (ii) All day efficiency of a transformer: It is the ratio of output energy in kWh to the input energy in kWh in the 24 hours of the day