A 400V/100 V, 10 KVA two-winding transformer is reconnected as an auto-transformer across a suitable

A 400V/100 V, 10 KVA two-winding transformer is reconnected as an auto-transformer across a suitable voltage source. The maximum rating of such an arrangement could be 

A) 50 KVA B) 15 KVA C) 12.5 KVA D) 8.75 KVA
by

1 Answer

Answer :

A 400V/100 V, 10 KVA two-winding transformer is reconnected as an auto-transformer across a suitable voltage source. The maximum rating of such an arrangement could be 50 KVA

by

Related questions

A single-phase, 50 kVA, 250 V/500 V two winding transformer has an efficiency of 95% at full load, unity

Description : 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%

Last Answer : A

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.

If a 220/440 V, 50 Hz, 5 KVA, single-phase transformer operates on 220V, 40Hz supply with secondary winding...

Description : If a 220/440 V, 50 Hz, 5 KVA, single-phase transformer operates on 220V, 40Hz supply with secondary winding open circuited: (A) both the eddy current and the hysteresis losses will decrease ... losses will increase (D) eddy current losses will increase but the hysteresis losses will remain the same

Last Answer : If a 220/440 V, 50 Hz, 5 KVA, single-phase transformer operates on 220V, 40Hz supply with secondary winding open circuited: both the eddy current and the hysteresis losses will decrease

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

A 1100 kVA, 11 kV/1.1 kV conventional two-winding transformer is connected as a 12.1 kV/11 kV step-down ...

Description : A 1100 kVA, 11 kV/1.1 kV conventional two-winding transformer is connected as a 12.1 kV/11 kV step-down auto-transformer. The rating of the auto-transformer is (A) 1000 kVA (B) 1100 kVA (C) 11000 kVA (D) 12100 kVA

Last Answer : A 1100 kVA, 11 kV/1.1 kV conventional two-winding transformer is connected as a 12.1 kV/11 kV step-down auto-transformer. The rating of the auto-transformer is 12100 kVA

KVA of an Auto-transformer of V1/V2 = 220/150 for a load of 100KVA is:

Description : KVA of an Auto-transformer of V1/V2 = 220/150 for a load of 100KVA is: a. 100KVA b. 50KVA c. 33.3KVA d. 20KVA 

Last Answer : KVA of an Auto-transformer of V1/V2 = 220/150 for a load of 100KVA is: a. 100KVA b. 50KVA c. 33.3KVA d. 20KVA 

A 10 kVA, 400 V/200 V single phase transformer with 10% impedance draws a steady

Description : A 10 kVA, 400 V/200 V single phase transformer with 10% impedance draws a steady short-circuit line current of   (a) 250A (b) 50 A (c) 150 A (d) 350 A 

Last Answer : A 10 kVA, 400 V/200 V single phase transformer with 10% impedance draws a steady short-circuit line current of 250A

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

52 A transformer has 1000 primary turns, connected to 250V ac supply. To get 400V secondary voltage the no of secondary turns should be A. 1600 B. 250 C. 400 D. 1250

Description : 52 A transformer has 1000 primary turns, connected to 250V ac supply. To get 400V secondary voltage the no of secondary turns should be A. 1600 B. 250 C. 400 D. 1250

Last Answer : A. 1600

What should be kVA rating of each transformer in V-V bank when three phase balanced load is

Description : 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

Last Answer : 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

An auto transformer is preferred over an ordinary two winding transformer due to: a) Safety of operation b) Availability of taps on secondary c) Copper savings d) All the above

Description : An auto transformer is preferred over an ordinary two winding transformer due to: a) Safety of operation b) Availability of taps on secondary c) Copper savings d) All the above

Last Answer : Ans: C

7 The main advantage of auto transformer over a two winding transformer is A. Hysteresis losses are reduced B. Saving in winding material C. Copper losses are negligible D. Eddy losses are totally eliminated

Description : 7 The main advantage of auto transformer over a two winding transformer is A. Hysteresis losses are reduced B. Saving in winding material C. Copper losses are negligible D. Eddy losses are totally eliminated

Last Answer : A) hysteresis losses is reduced

Compare auto transformer with two winding transformer.

Description : Compare auto transformer with two winding transformer.

Last Answer : Autotransformer and Two winding transformer

An Auto-transformer (which has only one winding) may be used as a ______ .

Description : An Auto-transformer (which has only one winding) may be used as a ______ .  (A) Both Step-Up and Step-Down transformer (B) Step-Down Transformer (C) Step-Up Transformer (D) None of these

Last Answer : An auto-transformer may be used as: A. Both Step-Up and Step-Down transformer An auto-transformer is a type of transformer that has only one winding and can be used as a step-up or ... size. Therefore, an auto-transformer is a versatile transformer that can be used for a variety of applications.

Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to

Description : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be

Last Answer : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be 25 N -m

A 100 kVA, 415 V(line), star-connected synchronous machine generates rated open circuit voltage of 415 V

Description : A 100 kVA, 415 V(line), star-connected synchronous machine generates rated open circuit voltage of 415 V at a field current of 15 A. The short circuit armature current at a field current of 10 A is equal to the ... unit saturated synchronous reactance is  (A) 1.731 (B) 1.5 (C) 0.666 (D) 0.577

Last Answer : 0.6

What causes a voltage to be developed across the secondary winding of a transformer?

Description : What causes a voltage to be developed across the secondary winding of a transformer?

Last Answer : The magnetic lines generated by the current in the primary cut

The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Description : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Last Answer : (C) 3.0 V.

The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary

Description : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be (A) 3.6 V. (B) 2.5 V. (C) 3.0 V. (D) 6.0 V.

Last Answer : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be 3.0 V.

The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary ...

Description : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be; (A) 3.6 (B) 2.5 V (C) 3.0 V (D) 6.0 V

Last Answer : The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The secondary output voltage will be: 3.0 V

The low voltage winding of a 400/230 V, 1-phase, 50 Hz transformer is to...

Description : The low voltage winding of a 400/230 V, 1-phase, 50 Hz transformer is to be connected to a 25 Hz, the supply voltage should be

Last Answer : The low voltage winding of a 400/230 V, 1-phase, 50 Hz transformer is to be connected to a 25 Hz, the supply voltage should be 115 V.

When two transformer of different kVA rating are connected in parallel they share the load in proportion to

Description : 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:

Last Answer : 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: P u impedance are equal

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.

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

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

[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

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

A 50 KVA transformer has iron loss 2 kW on full load. Calculate its iron loss at 75% of full load.

Description : A 50 KVA transformer has iron loss 2 kW on full load. Calculate its iron loss at 75% of full load.

Last Answer : Iron loss is dependent on voltage and independent of load. Hence iron loss at 75% of Load = Iron loss at full load = 2 kW

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 500 kVA, 3-phase transformer has iron losses of 300 W and full load copper losses of 600 W. The percentage

Description : 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%

Last Answer : 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%

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

A 4000 kVA, 11 kV/132 kV delta-star connected 3-phase transformer has reactance, x1 = 0.12 p.u.

Description : 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

Last Answer : 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 3.63 Ω

The kVA rating required for a transformer that must handle a maximum load current of 8 A with a ...

Description : The kVA rating required for a transformer that must handle a maximum load current of 8 A with a secondary voltage of 2 kV will be: A. 4 kVA B. 0.25 kVA C. 16 kVA D. 8 kVA

Last Answer : The kVA rating required for a transformer that must handle a maximum load current of 8 A with a secondary voltage of 2 kV will be: 16 kVA

One 200 KVA transformer has an iron loss of 1 KW and full load Cu loss of 2 KW. Its load KVA corresponding...

Description : 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 

Last Answer : 100

A single phase transformer rated at 3000 kVA, 69 kV 4.16 kV, 60 Hz has a total internal impedance Zp of 127...

Description : 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 

Last Answer : 543A

why transformer rating is measured in KVA?

Description : Transformer generally rated in KVA

Last Answer : The power of transformer is apparent power because it has no power factor and it is the product of voltage and current.

I need help with paying my past due gas bill in order to have it reconnected. I am on disability?

Description : I need help with paying my past due gas bill in order to have it reconnected. I am on disability?

Last Answer : If you contact your gas company and let them know your situation many will work with you, especially because you're on disability. Also the Christian Ministries or Salvation Army in your area may be able to assist you or be able to connect you with others who can assist you.

Batteries 'A' and 'B' shown in the illustration are 6 volts each and batteries 'C' and 'D' are 24 volts each. If 'A' and 'B' were reconnected to be in series-opposing to 'C' and 'D' respectively, the result would be _______________. EL-0039 A. 18 volts, negative at the top terminal B. 18 volts, positive at the top terminal C. 30 volts, negative at the bottom terminal D. 30 volts, positive at the bottom terminal

Description : Batteries 'A' and 'B' shown in the illustration are 6 volts each and batteries 'C' and 'D' are 24 volts each. If 'A' and 'B' were reconnected to be in series-opposing to 'C' and 'D' ... at the top terminal C. 30 volts, negative at the bottom terminal D. 30 volts, positive at the bottom terminal

Last Answer : Answer: A

If a CSD overheat warning is shown: a. The CSD can be disconnected and the pilot must control the alternator himself b. The pilot must throttle back to reduce the load on the alternator c. The CSD can be disconnected then reconnected later when the temperature has reduced d. The CSD can be disconnected but not used for the rest of the flight

Description : If a CSD overheat warning is shown: a. The CSD can be disconnected and the pilot must control the alternator himself b. The pilot must throttle back to reduce the load on the alternator c. The ... temperature has reduced d. The CSD can be disconnected but not used for the rest of the flight

Last Answer : d. The CSD can be disconnected but not used for the rest of the flight

If a CSD overheat warning is shown: a. The CSD can be disconnected and the pilot must control the alternator himself b. The pilot must throttle back to reduce the load on the alternator c. The CSD can be disconnected then reconnected later when the temperature has reduced d. The CSD can be disconnected but not used for the rest of the flight

Description : If a CSD overheat warning is shown: a. The CSD can be disconnected and the pilot must control the alternator himself b. The pilot must throttle back to reduce the load on the alternator c. The ... temperature has reduced d. The CSD can be disconnected but not used for the rest of the flight

Last Answer : d. The CSD can be disconnected but not used for the rest of the flight

N resistors of each of resistance R when connected in series offer an equivalent resistance of 50 ohm and when reconnected in parallel the effective resistance is 2 ohm the value of R is

Description : N resistors of each of resistance R when connected in series offer an equivalent resistance of 50 ohm and when reconnected in parallel the effective resistance is 2 ohm the value of R is

Last Answer : 25 ohms

How to connect two heating coils to three 400V phases?

Description : Hello. I need to connect two heating coils to three 400V phases. Don't know how? Thank you

Last Answer : Need Answer

Two voltmeters have the same range 0-400V. The internal impedance ...

Description : Two voltmeters have the same range 0-400V. The internal impedance are 30,000 Ohms and 20,000 Ohms. If they are connected in series and 600V be applied across them, the readings are

Last Answer : Two voltmeters have the same range 0-400V. The internal impedance are 30,000 Ohms and 20,000 Ohms. If they are connected in series and 600V be applied across them, the readings are 360V and 240V.

If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor

Description : If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor field with respect to stator filed is:

Last Answer : If a 3-phase, 400V, 50Hz, 4 pole induction motor is running at a slip of 5% then the relative speed of rotor field with respect to stator filed is: zero

The power input to the rotor of a 400V, 50 Hz 6 pole three phase induction motor is 20kW. The slip is 3%...

Description : The power input to the rotor of a 400V, 50 Hz 6 pole three phase induction motor is 20kW. The slip is 3%. The frequency of rotor currents is: (A) 1 Hz (B) 1.5 Hz (C) 2 Hz (D) 1 2 Hz

Last Answer : C