In an oil filled transformer, oil is provided for

In an oil filled transformer, oil is provided for (A) cooling (B) insulation (C) lubrication (D) both (A) and (B)
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In an oil filled transformer, oil is provided for (A) cooling (B) insulation (C) lubrication (D) both (A) and (B)

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Figure 'B' shown in the illustration represents a/an ____________. EL-0091 A. magnetic amplifier B. Scott-T transformer C. saturable-core reactor D. oil-filled toroid

Description : Figure 'B' shown in the illustration represents a/an ____________. EL-0091 A. magnetic amplifier B. Scott-T transformer C. saturable-core reactor D. oil-filled toroid

Last Answer : Answer: A

Figure 'A' shown in the illustration represents a/an _______________. EL-0091 A. magnetic amplifier B. Scott-T transformer C. saturable-core reactor D. oil-filled toroid

Description : Figure 'A' shown in the illustration represents a/an _______________. EL-0091 A. magnetic amplifier B. Scott-T transformer C. saturable-core reactor D. oil-filled toroid

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Last Answer : Ans: D

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Last Answer : Answer: Option B

A dash pot consists of a cylinder 10 cm in diameter in which slides a piston 12 cm long having a radial clearance of 1 mm. The cylinder is filled with oil having a viscosity of 1 poise. What will be the resistance offered by the piston to sliding with a velocity of 3 cm/sec a.1090 kg b.100 kg c.10900 kg d.10 kg e.50 kg

Description : A dash pot consists of a cylinder 10 cm in diameter in which slides a piston 12 cm long having a radial clearance of 1 mm. The cylinder is filled with oil having a viscosity of 1 poise. What will be the resistance offered ... with a velocity of 3 cm/sec a.1090 kg b.100 kg c.10900 kg d.10 kg e.50 kg

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What are the safety features of oil filled transformers?

Description : What are the safety features of oil filled transformers?

Last Answer : Environmental safety in case of spillage.There has to be a dyke wall for oil containment in case of spillage so that the oil does not get into ground / land.Oil level must be ... tested and minimum value must be maintained.Oil Cooling arrangement must be maintained.No leakage in radiators.

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Description : 07. A closed tank is completely filled with an oil. If it is made to move with a horizontal acceleration, then the pressure at the back end will be more than that at the front end. A) Correct B) Incorrect

Last Answer : A

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Description : It is difficult to maintain oil filled cables. (a) Yes (b) No

Last Answer : (a) Yes

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Description : The advantage of oil filled cables is (a) more perfect impregnation (b) smaller overall size (c) no ionisation, oxidation and formation of voids (d) all of the above

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Description : Cables, generally used beyond 66 kV are (a) oil filled (b) S.L. type (c) belted (d) armoured

Last Answer : (a) oil filled

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Description : For LV applications (below 1 kV), ______________ cables are used. (A) Paper insulated. (B) Plastic. (C) Single core cables. (D) Oil filled.

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Description : Oil-filled cable has a working stress of __________ kV/mm (A) 10 (B) 12 (C) 13 (D) 15

Last Answer : Ans: D This is defined by dielectric strength of mineral oil i.e. 15 kV/mm.

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Description : An Oil-filled cable has a working stress of ___________ kV/mm.  (A) 10 (B) 12 (C) 13 (D) 15

Last Answer : Answer : (D) 15

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Description : The transformer connection which has gained considerable popularity to serve 3-phase equipment and single phase lighting load is • Star/Star • Delta/Delta • Delta/Star • Star/Delta

Last Answer : The transformer connection which has gained considerable popularity to serve 3-phase equipment and single phase lighting load is Delta/Star

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Last Answer : Output transformer is always a Stepdown transformer

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Description : Transformer coupling introduces which type of distortion?

Last Answer : Transformer coupling introduces Cross over distortion.

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Description : In the illustrated 450 VAC system, what should be provided between the bus and the device labeled 'F'? EL-0003 A. a potential transformer B. a current transformer C. an emergency disconnect device D. an audible alarm and indicating light

Last Answer : Answer: A

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Description : How Transformer Protection provided for internal faults?

Last Answer : 1.Bucholz Relay (1st Stage Alarm and 2nd Stage Trip) 2.Sudden Pressure Relay (1st Stage Alarm and 2nd Stage Trip) 3.Pressure Relief Valve (1st Stage Alarm and 2nd Stage Trip) 4.Pressure Switch ... 8.Gas Temperature Indicator (Alarm) 9.Silicon Breather (Passive - no alarm) 10.Smoke Detector (Alarm)

What is the purpose of providing Taps in transformer and where these are provided?

Description : What is the purpose of providing Taps in transformer and where these are provided?

Last Answer : In order to attain the required voltage, taps are provided, normally at high voltages side(low current).

What is the speciality of the inverter output transformer? Why it is provided?

Description : What is the speciality of the inverter output transformer? Why it is provided? 

Last Answer : a) This eliminates all 3rd harmonics in the output voltage. b) Solid earthed neutral is required for the inverter output, hence the interconnected star winding is essential. c) ... will cause circulating current between inverters during unbalanced faults. The inverters cannot withstand this. 

In a tap changing transformer, the tappings are provided on (a) primary winding (b) secondary winding (c) high voltage winding (d) any of the above

Description : In a tap changing transformer, the tappings are provided on (a) primary winding (b) secondary winding (c) high voltage winding (d) any of the above

Last Answer : (b) secondary winding

In an IF amplifier, the IF transformer is provided with tapping to

Description : In an IF amplifier, the IF transformer is provided with tapping to  (a) increase the voltage gain (b) increase the bandwidth of the resonance circuit (c) increase the impedance ... resonance circuit to the following cascaded amplifier (d) increase the quality factor of the resonance circuit 

Last Answer : In an IF amplifier, the IF transformer is provided with tapping to increase the voltage gain

Laminations in the transformer core are provided to avoid

Description : Laminations in the transformer core are provided to avoid (a) continuous air gap (c) to reduce exiting current (b) to reduce the weight (d) to reduce copper losses

Last Answer : To reduce eddy current and hysterisis losses

In a transformer the tappings are generally provided on?

Last Answer : In a transformer, the tappings are generally provided on low voltage side.

Skimming tanks are A. Used to remove the grease and oil B. Those from which sludge is skimmed out C. Tanks provided with self- cleansing screens D. Improved version of grit chambers

Description : Skimming tanks are A. Used to remove the grease and oil B. Those from which sludge is skimmed out C. Tanks provided with self- cleansing screens D. Improved version of grit chambers

Last Answer : ANS: A

Mostly long span rail-cum road bridges are provided with a) rocker & roller bearings b) segmental roller with oil bath* c) Sliding bearings d) centralised bearings

Description : Mostly long span rail-cum road bridges are provided with a) rocker & roller bearings b) segmental roller with oil bath* c) Sliding bearings d) centralised bearings

Last Answer : b) segmental roller with oil bath

The calories provided by 100 grams of oil is: a. 700 Kcal b. 800 Kcal c. 900 Kcal d. 990 Kcal

Description : The calories provided by 100 grams of oil is: a. 700 Kcal b. 800 Kcal c. 900 Kcal d. 990 Kcal

Last Answer : c. 900 Kcal

What is the function of oil in transformer ?

Description : What is the function of oil in transformer ?

Last Answer : The job of transformer oil is to cool the transformer. So that the transformer does not get hot and burn.

What is the weight of one gallon of transformer oil?

Description : What is the weight of one gallon of transformer oil?

Last Answer : 7.6 pounds/gallon

Which type of oil is used as a transformer oil?

Description : Which type of oil is used as a transformer oil?

Last Answer : Transformer oil, or insulating oil, is usually a highly-refined mineral oil that is stable at high temperatures and has excellent electrical insulating properties. It is used in oil filled ... life, readily biodegradable, and have a lower volatility and higher flash points than mineral oil.

What is the function of transformer oil?

Description : What is the function of transformer oil?

Last Answer : A. Transformer Oil serves mainly two purposes 1. It acts as liquid insulation in electrical power transformer 2. It dissipates heat of the transformer i.e acts as coolant. In addition to these ... acid (C7, C8) esters are also becoming increasingly common as alternatives to naphthenic mineral oil.

Why transformer oil is used as a cooling medium?

Description : Why transformer oil is used as a cooling medium?

Last Answer : When transformer oil is used as a coolant the heat dissipation by convection is 10 times more than the convection due to air. Hence transformer oil is used as a cooling medium.

What is the function of transformer oil in a transformer ?

Description : What is the function of transformer oil in a transformer ?

Last Answer : Transformer oil provides , (i)good insulation and (ii)cooling . Nowadays instead of natural mineral oil, synthetic oils known as ASKRELS (trade name ) are used. They are non-inflammable ... an electric arc do not decompose to produce inflammable gases. PYROCOLOR oil possess high dielectric strength.

What is oil immersed type transformer?

Description : What is oil immersed type transformer?

Last Answer : In this type of transformer, oil is used as coolant. Entire assembly including core and windings is kept immersed in oil. The developed heat is transferred to the walls of tank through oil. Finally the heat is transferred to the surrounding air from tank wall by radiation.

Which of the following tests is not done for transformer oil? (A) Flash point and acid value (B) Aniline point (C) Dielectric strength (D) Copper strip corrosion test

Description : Which of the following tests is not done for transformer oil? (A) Flash point and acid value (B) Aniline point (C) Dielectric strength (D) Copper strip corrosion test

Last Answer : (B) Aniline poin

What are the types of oil used for in transformer for cooling?

Description : What are the types of oil used for in transformer for cooling? 

Last Answer : Paraffin based and naphtha based (in INDIA)  

Why there is no mixing of oil of tap changer and transformer?

Description : Why there is no mixing of oil of tap changer and transformer?

Last Answer : When the tap changing takes place arc is struck between the contacts. Due to this the oil inside the tap changer will be highly carbonised. If both oil get mixed up the quality of transformer tank oil will come down. This is not advisable. Hence both oils are kept separately. 

What is the requirement oil in a transformer?

Description : What is the requirement oil in a transformer?

Last Answer : Oil is used removal of heat produced in the transformer and also as insulating medium. 

Mention the properties of transformer oil.

Description : Mention the properties of transformer oil.

Last Answer : Properties of transformer oil are, a) Colour – pale yellow. b) Moisture content -

What is the normal value of moisture content allowed in transformer oil?

Description : What is the normal value of moisture content allowed in transformer oil? 

Last Answer :

What is gap between the electrodes in transformer oil testing kit?

Description : What is gap between the electrodes in transformer oil testing kit?

Last Answer : 0.1 Inch.

Which of the following has the lowest Prandtl number? (A) Molten sodium (a coolant used in fast breeder reactor) (B) Water (C) Transformer oil (D) Dilute H2SO4

Description : Which of the following has the lowest Prandtl number? (A) Molten sodium (a coolant used in fast breeder reactor) (B) Water (C) Transformer oil (D) Dilute H2SO4

Last Answer : (A) Molten sodium (a coolant used in fast breeder reactor)

The total permittivity of a dielectric transformer oil (relative permittivity is 2.2) will be (in order 10 -11 ) a) 1.94 b) 19.4 c) 0.194 d) 194

Description : The total permittivity of a dielectric transformer oil (relative permittivity is 2.2) will be (in order 10 -11 ) a) 1.94 b) 19.4 c) 0.194 d) 194

Last Answer : a) 1.94

Find the electric flux density surrounding a material with field intensity of 2xyz placed in transformer oil ( εr = 2.2) at the point P(1,2,3) is (in 10 -10 units) a) 2.1 b) 2.33 c) 2.5 d) 2.77

Description : Find the electric flux density surrounding a material with field intensity of 2xyz placed in transformer oil ( εr = 2.2) at the point P(1,2,3) is (in 10 -10 units) a) 2.1 b) 2.33 c) 2.5 d) 2.77

Last Answer : c) 2.5

Find the electric field intensity of transformer oil (εr = 2 approx) with density 1/4π (in 10 9 units) a) 2.5 b) 3.5 c) 4.5 d) 5.5

Description : Find the electric field intensity of transformer oil (εr = 2 approx) with density 1/4π (in 10 9 units) a) 2.5 b) 3.5 c) 4.5 d) 5.5

Last Answer : c) 4.5

Find the force of interaction between 60 stat coulomb and 37.5 stat coulomb spaced 7.5cm apart in transformer oil(εr=2.2) in 10 -4 N, a) 8.15 b) 5.18 c) 1.518 d) 1.815

Description : Find the force of interaction between 60 stat coulomb and 37.5 stat coulomb spaced 7.5cm apart in transformer oil(εr=2.2) in 10 -4 N, a) 8.15 b) 5.18 c) 1.518 d) 1.815

Last Answer : d) 1.815

D. Loading of the transformers not i76 The changes in volume of transformer cooling oil due to variation of atmospeheric temperature during day and night is taken care of by which part of transformer? A. Conservator B. Breather C. Bushings D. Buchholz relay

Description : 76 The changes in volume of transformer cooling oil due to variation of atmospeheric temperature during day and night is taken care of by which part of transformer? A. Conservator B. Breather C. Bushings D. Buchholz relay

Last Answer : A. Conservator

67 The chemical used in breather for transformer should have the quality of A. Ionizing air B. Absorbing moisture C. Cleansing the transformer oil D. Cooling the transformer oil

Description : 67 The chemical used in breather for transformer should have the quality of A. Ionizing air B. Absorbing moisture C. Cleansing the transformer oil D. Cooling the transformer oil

Last Answer : B. Absorbing moisture