Power consumed by a balanced star connected 3-phase load is measured using the two-wattmeter method. The phase voltage and phase current in the load is 220V and 10 A respectively. What will be the difference in reading (in W) of the two wattmeters, if the power factor of the system is 0.8 Lagging?

SSC JE Electrical 2018 with solution SET-1
Power consumed by a balanced star connected 3-phase load is measured using the two-wattmeter method. The phase voltage and phase current in the load is 220V and 10 A respectively. What will be the difference in reading (in W) of the two wattmeters, if the power factor of the system is 0.8 Lagging?

2861.2

3810.5

2286.3

3048.4

2861.2

3810.5

2286.3

3048.4

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SSC JE Electrical 2018 with solution SET-1
Determine the flux (in Wb) through a coil when the reluctance of the coil is 4 Amp-turns/Wb and the produced mmf is 48 Amp-turns

10

16

12

14

10

16

12

14

ANSWER EXPLANATION DOWNLOAD EXAMIANS APP

SSC JE Electrical 2018 with solution SET-1
Calculate the induced emf (in V) in the inductor of a series RL circuit having the inductance of 1.8 H and resistance of 90 Ohms after 20 milli-seconds when supplied by a 20 V DC source

14.76

10.03

20

7.36

14.76

10.03

20

7.36

ANSWER DOWNLOAD EXAMIANS APP

SSC JE Electrical 2018 with solution SET-1
Which one of the following statement is NOT true about PMMC type instruments?

Stray magnetic errors are small in these types of instruments

These instruments are suitable for both AC and DC currents

PMMC type Instruments have uniformly divided scale

The cost of PMMC instruments is high

Stray magnetic errors are small in these types of instruments

These instruments are suitable for both AC and DC currents

PMMC type Instruments have uniformly divided scale

The cost of PMMC instruments is high

ANSWER EXPLANATION DOWNLOAD EXAMIANS APP

SSC JE Electrical 2018 with solution SET-1
Which one of the following is a passive element to an electric circuit?

Resistors

Voltage source

Battery

Current source

Resistors

Voltage source

Battery

Current source

ANSWER EXPLANATION DOWNLOAD EXAMIANS APP

SSC JE Electrical 2018 with solution SET-1
Which of the following is a static exciter?

Amplidyne

Metadyne

Rectifier

DC Separately excited generator

Amplidyne

Metadyne

Rectifier

DC Separately excited generator

ANSWER EXPLANATION DOWNLOAD EXAMIANS APP

An AC or DC generator requires direct current to energize its magnetic field. The DC field current is obtained from a separate source called an exciter. Either rotating or static-type exciters are used for AC power generation systems. There are two types of rotating exciters: brush and brushless. The primary difference between brush and brushless exciters is the method used to transfer DC exciting current to the generator fields. Static excitation for the generator fields is provided in several forms including field-flash voltage from storage batteries and voltage from a system of solid-state components. DC generators are either separately excited or self-excited.
EXCITATION SYSTEMS in current use include direct-connected or gear-connected shaft-driven DC generators, belt-driven or separate prime mover or motor-driven DC generators, and DC supplied through static rectifiers.
Static Excitation System
As the name indicates, all the components in this type of excitation system are static. A set of rectifiers is fed from a transformer that steps down the main generator or auxiliary bus voltage. The rectifiers supply the main generator excitation current directly through slip rings and they may be controlled or uncontrolled.

An external source of DC is necessary for the initial excitation of the field windings. On engine-driven generators, the initial excitation may be obtained from the storage batteries used to start the engine or from control voltage at the switchgear.
The main advantage of the static exciter is improved response as the field current is controlled directly by the thyristor rectifier but, of course, if the generator terminal voltage is depressed too low then excitation power will be lost. It is again possible to provide the power supply from both voltage and current transformers at the generator terminals but it is doubtful whether the improved response of the static exciter over a permanent magnet brushless scheme can be justified for many small embedded generators.

SSC JE Electrical 2018 with solution SET-1

SSC JE Electrical 2018 with solution SET-1 Determine the flux (in Wb) through a coil when the reluctance of the coil is 4 Amp-turns/Wb and the produced mmf is 48 Amp-turns

SSC JE Electrical 2018 with solution SET-1 Calculate the induced emf (in V) in the inductor of a series RL circuit having the inductance of 1.8 H and resistance of 90 Ohms after 20 milli-seconds when supplied by a 20 V DC source

SSC JE Electrical 2018 with solution SET-1 Which one of the following statement is NOT true about PMMC type instruments?

SSC JE Electrical 2018 with solution SET-1 Which one of the following is a passive element to an electric circuit?

SSC JE Electrical 2018 with solution SET-1 Which of the following is a static exciter?

SSC JE Electrical 2018 with solution SET-1
Determine the flux (in Wb) through a coil when the reluctance of the coil is 4 Amp-turns/Wb and the produced mmf is 48 Amp-turns

SSC JE Electrical 2018 with solution SET-1
Calculate the induced emf (in V) in the inductor of a series RL circuit having the inductance of 1.8 H and resistance of 90 Ohms after 20 milli-seconds when supplied by a 20 V DC source

SSC JE Electrical 2018 with solution SET-1
Which one of the following statement is NOT true about PMMC type instruments?

SSC JE Electrical 2018 with solution SET-1
Which one of the following is a passive element to an electric circuit?

SSC JE Electrical 2018 with solution SET-1
Which of the following is a static exciter?