What is meant by KVA?

What is meant by KVA?
by

2 Answers

Answer :

kVA is the unit of Apparent power. kVA means kilovolt ampere.
by

Answer :

KVA - kilo volt ampere 

Used to specify the transformer details
by

Related questions

What is difference between KW and KVA?

Description : What is difference between KW and KVA?

Last Answer : kW is kilowatt and kVA is kilovolt ampere. kW is unit of real power and kVA is unit of Apparent power.

Why are generators rated in kVA not in kW ?

Description : Why are generators rated in kVA not in kW ?

Last Answer : Because It's rating of generator kva is apparent power. Kw is active power which we use. And one is kvar reactive power.

Why Transformer rating is given in kVA?

Description : Why Transformer rating is given in kVA?

Last Answer : Because of core losses and iron losses as core losses are measured in amps and cu losses in voltage ....this is definatly reason for the rating Or kVA is the unit for apparent power. Apparent ... shift between voltage and current). So a transformer has to be rated (and selected) by apparent power.

Define kVA rating of transformer.

Description : Define kVA rating of transformer.

Last Answer : kVA rating of transformer is defined as the product of voltage (V) and current (I) on primary side of transformer or secondary side of transformer divided by 1000. On both side the VA rating remains ... Mathematically kVA rating is given by, kVA rating of transformer = V1I1/1000 =V2I2/1000

A 40 kVA transformer has a core loss of 400 W and a full load copper loss of 800 W. The

Description : 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

Last Answer : 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 0.707

The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be :

Description : 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

Last Answer : The kVA rating of Three-phase transformer with Voltage = 200V and Current = 100A will be : 34.64 kVA

The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is?

Description : The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is?

Last Answer : The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is 6 kVAR.

Can you have a power factor greater than 1?

Description : Can you have a power factor greater than 1?

Last Answer : We cannot have power factor greater than 1. As it is a measure of cosine of angle between voltage and current. 

What is the best power factor?

Description : What is the best power factor?

Last Answer : It is unity power factor but difficult to achieve in dynamic loads

How much is 1 unit of electricity?

Description : How much is 1 unit of electricity?

Last Answer : 1 unit of electricity is equal to 1 kWh.

What is the advantage of high power factor?

Description : What is the advantage of high power factor?

Last Answer : Reduced copper losses Smaller conductor size Improve voltage regulation Increase system capability Less energy bill

What are the main causes of harmonics?

Description : What are the main causes of harmonics?

Last Answer : Harmonic is a non linear load because linear load voltage deviated due to connection of some electrinie device such as converter,inverter

How do you measure power factor?

Description : How do you measure power factor?

Last Answer : P= 1.83*V*I*COS@ where P is power           V is voltage            I is current           COS @ is P.F COS@= P/(1.83*V*I)  in other way cos @ = true power/apparent power

What causes transients?

Description : What causes transients?

Last Answer : Transient is a peak voltage take small period. It will occur due to lightning

What causes lights to dim in house?

Description : What causes lights to dim in house?

Last Answer : While taking a more load from other Equipment

What would cause a power surge in a house?

Description : What would cause a power surge in a house?

Last Answer : If your neibour / other flat owners / your maintainer staff switch on any type of inductive load that can cause power surge / dip  

why power quality is important?

Last Answer : Power quality is important because the electrical appliances will works better and will be safer and less loss in energy. Low energy waste and improves stability of power system .

how to monitor power quality?

Last Answer : By applying various power quality monitoring devices and using telecommunication technique .

what is trickle charging ?

Description : what is trickle charging ?

Last Answer : It is the process of charging a fully charged battery at the rate equal to its own discharge rate. This process ensures that the battery remains fully charged. It is carried out only when the battery is not connected to the load.

what is UPS ?

Description : what is UPS ?

Last Answer : UPS is Uninterrupted Power Source

what is UPS and what are its uses?

Description : what is UPS and what are its uses?

Last Answer : Ups means uninterrupted power supply It supplies power when there is power supply outage. This is done by storing power in battery banks while power is on and then during power outage the DC in battery is converted to a.c by inverters

Assertion : Kilovol-ampere (kVA) and kilowatt-hour have the same dimensions. Reason : Both are the units of energy.

Description : Assertion : Kilovol-ampere (kVA) and kilowatt-hour have the same dimensions. Reason : Both are the units of energy.

Last Answer : Assertion : Kilovol-ampere (kVA) and kilowatt-hour have the same dimensions. Reason : Both are the ... . D. If both Assertion and Reason are false.

What is 10 KVA Online UPS Price in India?

Description : What is 10 KVA Online UPS Price in India?

Last Answer : 10 kva ups price in India is extremely high in the market, and it is tough to sustain. 10 kva online ups price with Nexus is affordable and is available all over India. Thus, visit our website, and your ... search of 10 kva ups price in India at a cheap price, no other can beat the service of Nexus.

How many amps is 7.5 kva?

Description : How many amps is 7.5 kva?

Last Answer : 7.5kVA is a value derived from the voltage multiplied by the current. Without knowing one, you cannot know the other. For example, think of the number 10kVA This could be made by :10kV * 1A or 5kV * 2A or 1kV * 10A or 2kV * 5A. You couldn't possibly know which is the initial pair.

How many amps is 7.5 kva?

Description : How many amps is 7.5 kva?

Last Answer : 7.5kVA is a value derived from the voltage multiplied by the current. Without knowing one, you cannot know the other. For example, think of the number 10kVA This could be made by :10kV * 1A or 5kV * 2A or 1kV * 10A or 2kV * 5A. You couldn't possibly know which is the initial pair.

The division of the reactive KVA load between paralleled AC generators is initiated by the ______________. A. prime mover governors B. voltage regulators C. phase balance relay D. proportioner

Description : The division of the reactive KVA load between paralleled AC generators is initiated by the ______________. A. prime mover governors B. voltage regulators C. phase balance relay D. proportioner

Last Answer : Answer: B

Attempting to parallel an AC generator which is out of phase with the bus will result in which of the following problems? A. The breaker should trip. B. The KVA will decrease. C. The synchronizing lamps will burn out. D. The power factor will be unitized.

Description : Attempting to parallel an AC generator which is out of phase with the bus will result in which of the following problems? A. The breaker should trip. B. The KVA will decrease. C. The synchronizing lamps will burn out. D. The power factor will be unitized.

Last Answer : Answer: A

The unit of apparent power in a purely inductive circuit is called the _____________. A. kva B. var C. emf D. watt

Description : The unit of apparent power in a purely inductive circuit is called the _____________. A. kva B. var C. emf D. watt

Last Answer : Answer: B

What is the maximum current allowed to be drawn from the secondary of a 2 KVA step-down transformer with a turns ratio of four to one if connected across a 440 volt line? A. 1.1 amps B. 4.5 amps C. 18.1 amps D. 22.7 amps

Description : What is the maximum current allowed to be drawn from the secondary of a 2 KVA step-down transformer with a turns ratio of four to one if connected across a 440 volt line? A. 1.1 amps B. 4.5 amps C. 18.1 amps D. 22.7 amps

Last Answer : Answer: C

What is the maximum allowable primary current of a 2 KVA step-down transformer with a four to one turns ratio if connected across a 440 volt line? A. 1.1 amps B. 4.5 amps C. 18.1 amps D. 27.7 amps

Description : What is the maximum allowable primary current of a 2 KVA step-down transformer with a four to one turns ratio if connected across a 440 volt line? A. 1.1 amps B. 4.5 amps C. 18.1 amps D. 27.7 amps

Last Answer : Answer: B

How do we select a cable for a machine as per standards? Is there is any standard to select a cable as per voltage, or as per KVA and as per amps ratings?

Description : How do we select a cable for a machine as per standards? Is there is any standard to select a cable as per voltage, or as per KVA and as per amps ratings?

Last Answer : Cable size depends upon current carrying capacity and voltage to withstand, to select cable size we must have knowledge of load of machine and operating voltage

Why we do 2 types of earthing on transformer i.e.: body earthing & neutral earthing, what is function. I am going to install a 5oo kva transformer & 380 kva DG set what should the earthing value?

Description : Why we do 2 types of earthing on transformer i.e.: body earthing & neutral earthing, what is function. I am going to install a 5oo kva transformer & 380 kva DG set what should the earthing value?

Last Answer : The two types of earthing are Familiar as Equipment earthing and system earthing. In Equipment earthing: body (non conducting part) of the equipment should be earthed to safeguard the human ... earthing will be further classified into directly earthed, Impedance earthing, resistive (NGRs) earthing.

Can Transformers be Reconnected as Autotransformers to Increase Their KVA Rating?

Description : Can Transformers be Reconnected as Autotransformers to Increase Their KVA Rating?

Last Answer : ANSWER: Several of standard single phase transformers can be connected as autotransformers. The KVA capacity will be greatly increased when used as an Autotransformer, in comparison to the ... This voltage is normally used for operating fluorescent lamps or similar devices requiring 277 volts

Why alternators are rated in KVA?

Description : Why alternators are rated in KVA?

Last Answer : The KVA rating of ac machine depends on the power factor of the load. The power factor in turn depends on the operating conditions. The operating conditions differ from place to place. Therefore the KVA rating is specified for all ac machines.

Why are Alternators rated in kVA and not in kW?

Description : Why are Alternators rated in kVA and not in kW?

Last Answer : The continuous power rating of any machine is generally defined as the power the machine or apparatus can deliver for a continuous period so that the losses incurred in the machine gives rise to a ... generator , the Alternators have only their apparent power in VA/kVA/MVA as their power rating.

why transformers are rated in kVA ?

Description : why transformers are rated in kVA ?

Last Answer : A:Copper loss of a transformer depends on current and iron loss on voltage . Hence total losses depends on Volt- Ampere and not on the power factor. That is why the rating of transformers are in kVA and not in kW.

Current employed in resistance welding ranges from __________ kVA/cm2. (A) 1.2 to 2.5 (B) 4.5 to 6.2 (C) 7.5 to 8.5 (D) 10.5 to 15.5

Description : Current employed in resistance welding ranges from __________ kVA/cm2. (A) 1.2 to 2.5 (B) 4.5 to 6.2 (C) 7.5 to 8.5 (D) 10.5 to 15.5

Last Answer : Option B

For which of the following ratings of the transformer differential protection is recommended ? (a) above 30 kVA. (b) equal to and above 5 MVA (c) equal to and above 25 MVA (d) none of the above

Description : For which of the following ratings of the transformer differential protection is recommended ? (a) above 30 kVA. (b) equal to and above 5 MVA (c) equal to and above 25 MVA (d) none of the above

Last Answer : (b) equal to and above 5 MVA

Why are motor ratings given in KW and that of alternator and transformer given in KVA?

Description : Why are motor ratings given in KW and that of alternator and transformer given in KVA?

Last Answer : kW is the output mechanical power of a motor and is expressed in kW. kVA is the net (apparent) power input to the transformer. This input power is the output + losses. kW = kVA x system power factor

What is KVA?

Description : What is KVA?

Last Answer : Kilo volt-ampere (kVA) is the unit used for the apparent power in an AC electrical circuit. It is the product of root-mean-square (RMS) voltage and RMS current. It is given by S = P + jQ Where S is the apparent power in kVA P is the real power in kW and Q is the reactive power in kVAr

The term missing in the following equation (kVA) 2 = (kVA cos phi) 2 + ( ? )2 is a) cos phi b) sin phi c) kVA sin phi d) kVArh

Description : The term missing in the following equation (kVA) 2 = (kVA cos phi) 2 + ( ? )2 is a) cos phi b) sin phi c) kVA sin phi d) kVArh

Last Answer : c) kVA sin phi

Which of the following statements are true? i) reactive current is necessary to build up the flux for the magnetic field of inductive devices ii) some portion of reactive current is converted into work iii) the cosine of angle between kVA and kVAr vector is called power factor iv) the cosine of angle between kW and kVA vector is called power factor a) i & iv b) ii & iii c) i & iii d) iii & iv

Description : Which of the following statements are true? i) reactive current is necessary to build up the flux for the magnetic field of inductive devices ii) some portion of reactive current is converted into work iii) the cosine of angle ... called power factor a) i & iv b) ii & iii c) i & iii d) iii & iv

Last Answer : a) i & iv

A building intended to be used for commercial purpose will be required to follow Energy conservation building code under Energy Conservation Act, 2001 provided its a) connected load is 120 kW and above b) contract demand is 100 kVA and above c) connected load is100 kW and above or contract demand is 120 kVA and above

Description : A building intended to be used for commercial purpose will be required to follow Energy conservation building code under Energy Conservation Act, 2001 provided its a) connected load is 120 kW and above b) ... and above c) connected load is100 kW and above or contract demand is 120 kVA and above

Last Answer : c) connected load is100 kW and above or contract demand is 120 kVA and above

[75] Two transformers are connected in parallel. These transformers do not have equal percentage impedance which results A. Short-circuiting of the secondaries B. Power factor of one of the transformers is leading while that of the other lagging C. Transformers having higher copper losses will have negligible core losses D. Loading of the transformers not in proportion to their kVA ratings.

Description : [75] Two transformers are connected in parallel. These transformers do not have equal percentage impedance which results A. Short-circuiting of the secondaries B. Power factor of one of the ... have negligible core losses D. Loading of the transformers not in proportion to their kVA ratings.

Last Answer : D. Loading of the transformers not in proportion to their kVA ratings

55 When a 400Hz transformer is operated at 50Hz its KVA rating is A. Reduced to 1/8 B. Increased 8 times C. Unaffected D. Increased 64 times 56

Description : 55 When a 400Hz transformer is operated at 50Hz its KVA rating is A. Reduced to 1/8 B. Increased 8 times C. Unaffected D. Increased 64 times

Last Answer : A. Reduced to 1/8

54] In operating a 400hz transformer at 50Hz A. Only voltage is reduced in the same proportion as the frequency B. Only KVA rating is reduced in the same proportion as the frequency C. Both voltage and KVA rating are reduced in the same proportion as frequency d. None of the above

Description : 4] In operating a 400hz transformer at 50Hz A. Only voltage is reduced in the same proportion as the frequency B. Only KVA rating is reduced in the same proportion as the frequency C. Both voltage and KVA rating are reduced in the same proportion as frequency D. None of the above

Last Answer : B. Only KVA rating is reduced in the same proportion as the frequency

47 Cross over windings are used in A. Low voltage side of high kVA rating transformers B. Current transformers C. High voltage side of high kVA rating transformers D. High voltage side of low kVA rating transformers

Description : 47 Cross over windings are used in A. Low voltage side of high kVA rating transformers B. Current transformers C. High voltage side of high kVA rating transformers D. High voltage side of low kVA rating transformers

Last Answer : D. High voltage side of low kVA rating transformers

[23] Transformers are rated in KVA instead of KW because A. load power factor is often not known B. KVA is fixed whereas KW depends on load power factor C. Total transformer loss depends on volt ampere D. It has become customary

Description : [23] Transformers are rated in KVA instead of KW because A. load power factor is often not known B. KVA is fixed whereas KW depends on load power factor C. Total transformer loss depends on volt ampere D. It has become customary

Last Answer : C. Total transformer loss depends on volt ampere

A 220/440 V, 50 Hz, 5 KVA, single phase transformer operates on 220V, 40Hz supply with secondary winding open circuited. Then (A) Both eddy current and hysteresis losses decreases. (B) Both eddy current and hysteresis losses increases. (C) Eddy current loss remains the same but hysteresis loss increases. (D) Eddy current loss increases but hysteresis loss remains the same.

Description : A 220/440 V, 50 Hz, 5 KVA, single phase transformer operates on 220V, 40Hz supply with secondary winding open circuited. Then (A) Both eddy current and hysteresis losses decreases. (B) Both ... same but hysteresis loss increases. (D) Eddy current loss increases but hysteresis loss remains the same.

Last Answer : (A) Both eddy current and hysteresis losses decreases.

The transformer ratings are usually expressed in terms of A. Volts B. Amperes C. kW D. kVA

Description : The transformer ratings are usually expressed in terms of A. Volts B. Amperes C. kW D. kVA

Last Answer : D) KVA