HPSSSB JE Electrical Mock Test

HPSSSB JE Electrical Mock Test our mock help you prepare for the upcoming JE electrical exam of HPSSC

HPSSSB JE Electrical Solved Question Paper 2021

1) The basic function of a transformer

A) The level of voltage
B) the power level
C) the power factor
D) Transient

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A) The level of voltage
Exp-: In a transformer, the energy transfer takes place with a change of voltage supply frequency of output remains the same as that of the input. Power factor level are almost the same on both sides of the transformer.

2) The efficiency of a power transformer is around

A) 50%
B) 60%
C) 80%
D) 95%

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D) 95%
Exp-:Transformer is a static machine owing to absence of rotating parts are no there are no friction or windage losses. Further the other losses are also relatively low, so that the efficiency of transformer. is high

3) In a transfomer electrical power is transferred from primary to secondary

A) through air
B) By magnetic flux
C) through insulating medium
D) electrically linked

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B) by magnetic flux
Exp-: The transformer work on the principle of faraday law of electro-magnetic induction which state that when the rate of change of flux linking change there is emf induce therefore the flux is created by the primary also link with secondary and the flux of secondary interact with primary then there is a emf induce and power is transfer form primary to secondary through magnetic flux

4) The flux is created by the current flowing through the primary winding induces emf in

A) Primary winding onnly
B)Secondary winding only
C)Transformer core only
D)both primary and secondary windinngs

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D) Both primary and secondary windings
Exp-: Because the flux created by the primary also link with secondary and the rate of change of flux linking is change and emf is induce in both the winding bcoz of interaction of primary and secondary flux

5) On no load phasor diagram of transformer, the core loss component of the current ramains in phase with

A) No load current
B) Primary supply voltage
C) Core flux
D) primary induced voltage

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B) Primary supply voltage
Exp-: The Working component or core less component or active component is in phase with the applied voltage. It supplies the iron losses and a small primary copper loss.

6) The power factor of a power transformer on no load will be about

A) unity
B) .75
C) .5
D) .35

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D) .35
Exp-: The exciting or no-load current I_O is made up of a relatively large magnetizing component I_m and a comparatively small in-phase or energy componennt I_e so the power factor of a transformer on no load is very small and it is due to magnetising reactance of the transformer

7) The core flux of a practical trannsformer with a resistance load

A) is strictly constant with load changes
B) increases linerly with load
C) increase as the square root of the load
D) decrease with increase of load

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A) Is strictly constant with load changes
Exp-: core flux is directly proportional to supply voltage and inversly proportional to supply frequency so it independent of load

8) The flux in a transformer

A) increases with load
B) decrease with load
C) remains constant irrespective of load
D) none of the above

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C) Remain constant irrespective of load
Exp-: Since the secondary flux φ₂ produced by seconndary mmf N₂I₂ is neutralized by the flux φ^'₁ produced by mmf N₁I^' set up by conterbalancing primary current I ^'₁  , the flux in the transformer core remains constant from no load to full load

9) The condition for maximum efficiency of the transformer is that

A) copper losses are half of the iron loss
B) coper losses are square of the iron losses
C) copper losses are equal to the iron losses
D) copper losses are zero

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C) Copper loss are equal to iron losses

10) The use of higher flux density in the transformer design

A) reduce the weight per KVA
B) increase the weight per KVA
C) has no relation with with the weight of transformer
D) increase the weight per KW

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A) Reduce the weight per KVA
flux density=φ/A Therefore flux density is inversely proportional to area, weight will reduces for higher flux density.

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