# what are the uses of current transformer ?

what are the uses of current transformer ?

Uses of current transformer are as follows :

A current transformer is use to measure Alternating current.

A current transformer is used in meters.

A current transformer is used in ammeters.

Current transformer is use with compensator.

Current transformer is use in power factor meters.

Current transformer is use in watthour meters.

Current transformer is use with relay.

Current transformer is use with circuit breaker.

Current transformer is use for overcurrent fault protection.

## Related questions

Description : The core of a transformer (medium size) uses to provide high flux densities (a) diamagnetic (c) ferromagnetic core (b) paramagnetic (d) none of these

Answer : The core of transformer is made up colled rolled grain oriented. It is a ferromagnetic material..

Description : Computation of branch current uses: A. Kirchhoff's voltage and current laws B. Thevenin's theorem and Ohm's law C. Kirchhoff's current law and Ohm's law D. Superposition theorem and Thevenin's theorem

Answer : Computation of branch current uses: Kirchhoff's voltage and current laws

Answer : A fridge uses 220 watts from 110 V power source. The Fridge then draws a current from the source equal to 2 amps.

Description : a single phase full wave midpoint thyristor converter uses a 230/200V transformer with centre tap on the secondary side. The P.I.V per thyristor is   (A) 100V (B)141.4V (C)200V (D)282.8V

Description : With the help of neat diagram, explain the construction of current transformer.

Answer : Construction of current transformer:   C.T. has bar type conductor, which behaves as primary winding. The primary of C.T. carries large current Ip which is to be measured, so the bar ... sectional area is small. An ammeter of small range is connected across the secondary as shown in figure.

Description : For a traction transformer circuit breaker state: 1) Rated current and rupturing capacity 2) Any two tests it should be capable of withstanding 3) Overall tripping time and relay time.

Answer : Ans: 1) Rated current --- 750 A and Rupturing capacity --- 500 MVA  2) Any two tests it should be capable of withstanding --- Breaking test , Reclosing test , Endurance test ( any two )  3) Overall tripping time --- 0.14 sec and Relay time --- 0.04 sec

Description : 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.

Description : Step-down transformer converts high voltage and low current into:  (A) How voltage and high current (B) High voltage and low current (C) Low voltage and high current (D) None of the above

Answer : Step-down transformer converts high voltage and low current into: Low voltage and high current

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

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

Description : A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are (A) 140 W (B) 180 W (C) 240 W (D) 480 W

Answer : A transformer at 25 Hz develops 20 W hysteresis loss and 50 W eddy current loss. If the applied voltage and frequency are doubled, the new core losses are 240 W

Description : Eddy current losses in transformer cores can be reduced by the use of  1. Solid cores  2. Laminated cores  3. Ferrites  Select the correct answer using the codes given below : (a) 2 and 3 only (b). 1 and 2 only (c) 1 and 3 only (d) 1, 2 and 3

Answer : Eddy current losses in transformer cores can be reduced by the use of  1. Solid cores  2. Laminated cores  3. Ferrites  Select the correct answer using the codes given below : (a) 2 and 3 only (b). 1 and 2 only (c) 1 and 3 only (d) 1, 2 and 3

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

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

Description : In case of a power transformer, the no load current in terms of rated current is (1) 10-20% (2) 15-30% (3) 2-6% (4) 30-50%

Description : The ratio error in current transformer is due to:  (1) Power factor of primary. (2) Wattless component of the current in the primary (3) Exciting current (4) Leakage flux

Answer : The ratio error in current transformer is due to: Exciting current.

Description : A large transformer operating at no load draws an exciting current Io of 5A, when the primary is connected to a 120 V, 60 Hz source. From a wattmeter test, it is known that iron losses are equal to 180 W. Calculate ... power absorbed by the core.  (A) 600 var (B) 572 var (C) 180 var (D) 360 var

Description : How eddy current is produced in a transformer?

Description : The doorbell on your house requires a 12 volt alternating current. A transformer having a primary winding of 1,600 turns is to be used to step down your house's 110-volt alternating current. How many turns are there on the secondary winding?

Answer : The inverse definite mean time relays are used for over current and earth fault protection of transformer against internal short-circuits.

Description : What are the uses of Thermistors ?

Answer : Thermistors are frequently used in electronic circuits in which it is desired to provide temperature measurement, temperature control, and temperature compensation.

Answer : Uses of ceramic capacitors is as follows :The ceramic capacitor is use in DC to DC converter.The ceramic capacitor is use with band pass and band stop filter.Ceramic capacitor ... The ceramic capacitor is uses in high frequency circuits.Ceramic capacitors are use for biasing applications.

Description : What is the name of the device used to convert alternating current into direct current ? (1) Ammeter (2) Galvanometer (3) Rectifier (4) Transformer

Description : What is the line current of a circuit when the current transformer of 1000 : 5 rating measures 4 amp? (A) 5000 amp (B) 1000 amp (C) 400 amp (D) 800 amp

Answer : What is the line current of a circuit when the current transformer of 1000 : 5 rating measures 4 amp? (A) 5000 amp (B) 1000 amp (C) 400 amp (D) 800 amp

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

Answer : Transformer noise is generated due to vibration of core and winding this is because of magnetostriction and magnetomotive force.

Description : what are the types of transformer ?

Answer : Power transformer, instrument transformer, pulse transformer, RF transformer, IF transformer, audio transformer, distribution transformer etc. are the types of transformer.

Description : Two light bulbs are connected in series across a 120 V battery. Bulb 1 uses 40 W of power and Bulb 2 uses 20 W of power. If bulb 1 alone is connected to the 120 V source, then it will consume (A) 90 W (B) 80 W (C) 60 W (D) 180 W

Answer : Two light bulbs are connected in series across a 120 V battery. Bulb 1 uses 40 W of power and Bulb 2 uses 20 W of power. If bulb 1 alone is connected to the 120 V source, then it will consume 90 W

Description : A transformer works with (1) alternating current only (2) direct current only (3) both AC and DC (4) any signal

Description : Alternating current is converted into direct current by a (1) transformer (2) dynamo (3) oscillator (4) rectifier

Description : “Secondary of current transformer should not be open”. Justify.

Answer : Secondary of a CT should not be Open Circuited: If secondary of CT is open circuited ,then current through secondary becomes zero hence the ampere-turns produced by secondary which generally opposes primary ... opeartor point of view as well. So secondary of a CT should not be open circuited.

Description : Even at no-load, a transformer draws current from the mains. Why?

Description : Explain over-current protection of transformer.

Answer : Over-Current Protection of Transformer: Simple over-current & earth fault protection of transformer against external shortcircuit and excessive overloads is shown in the above figure. The ... trip command to the circuit breaker and the transformer is disconnected from load or fault.

Description : Define: 1) voltage ratio, 2) current ratio, 3) transformation ratio of transformer.

Answer : 1) Voltage ratio: The voltages in primary and secondary winding is proportional to number of turns in primary and secondary respectively. So, the voltage ratio is same as transformation ratio. V2/V1 = N2 ... as transformation ratio of transformer. It is denoted by K. K = N2/N1

Description : The current transformer that is used to measure a 100 A current by 5 A ammeter is a_____.

Answer : The current transformer that is used to measure a 100 A current by 5 A ammeter is a step up transformer

Description : A current transformer must at all times have (a) a secondary load (b) short circuited secondary (c) either (a) or (b) (d) none of these

Description : The burden of protective Current Transformer (CT) is specified in

Answer : The burden of protective Current Transformer (CT) is specified in Volt - Ampere

Description : 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

Answer : 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 20, 36

Description : For a constant load current, transformer maximum efficiency occurs at   (a) any power factor (b) zero power factor leading (c) zero power factor lagging (d) unity power factor

Answer : For a constant load current, transformer maximum efficiency occurs at unity power factor

Description : The operating point of a protective current transformer is near the

Answer : The operating point of a protective current transformer is near the Ankle point

Description : The inrush current of a transformer at no load is maximum if the supply voltage is switched on  (1) at peak voltage value (2) at zero voltage value (3) at half voltage value (4) at 0.866 time voltage value

Answer : At 0.866 time voltage value

Description : In a single-phase transformer, the magnetizing current is (A) in phase with the no-load current (B) in quadrature with the no-load current (C) the product of no-load current and power factor (D) in phase with the flux in the core

Answer : In a single-phase transformer, the magnetizing current is in phase with the flux in the core

Description : No load current in a transformer: (A) lags the applied voltage by 90° (B) lags the applied voltage by somewhat less than 90° (C) leads the applied voltage by 90° (D) leads the applied voltage by somewhat less than 90°

Answer : No load current in a transformer: lags the applied voltage by somewhat less than 90°

Answer : The no load current in a transformer lags behind the applied voltage by an angle of about 75°.

Answer : No-load current of a transformer has small magnitude and low power factor.

Answer : The magnetising current of a transformer is usually small because it has small air gap.

Description : When secondary of a current transformer is open-circuited its iron core will be?

Answer : When secondary of a current transformer is open-circuited its iron core will be hot because of heavy iron losses taking place in it due to high flux density.

Description : The secondary of a current transformer is always short-circuited under operating conditions because it?

Answer : The secondary of a current transformer is always short-circuited under operating conditions because it avoids core saturation and high voltage induction.

Description : For a transformer, operating at constant load current, maximum efficiency will occur at?

Answer : For a transformer, operating at constant load current, maximum efficiency will occur at unity power factor.

Description : In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of?

Answer : In a step-down transformer, there is a change of 15 A in the load current. This results in change of supply current of less than 15A.