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A phase shifting transformer is used in conjunction with Drysdale potentiometer.

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The stator of phase shifting transformer for use in conjunction with an A.C. potentiometer usually has a two-phase winding.

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Explain the procedure to perform Short Circuit test on single phase transformer with circuit diagram.

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A single phase transformer has resistance and reactance of 0.2 pu and 0.6 pu respectively. Its pu voltage regulation at 0.8 pf lagging would he

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A single phase transformer has resistance and reactance of 0.2 pu and 0.6 pu respectively. Its pu voltage regulation at 0.8 pf lagging would he 0.52

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Single phase transformer

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Single phase Transformer Transformer

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Explain construction and working principle of single phase transformer.

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A single phase transformers is an electrical device that accepts single-phase AC power and outputs single-phase AC. PRINCIPLE... The single-phase transformer works on the principle of ... and secondary windings. Thin steel laminations shall be employed to prevent power losses from the core.

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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

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

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Which of the following 3-phase connection of a transformer causes interference with the neighbouring communication lines:  (A) Delta-Star (B) Star-Delta (C) Delta-Delta (D) Star-Star

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Which of the following 3-phase connection of a transformer causes interference with the neighbouring communication lines: Star-Star

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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

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

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In a single phase power factor meter the phase difference between the currents in the two pressure coils is exactly 90°.

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Induction type single phase energy meters measure electric energy in kWh.

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When a V-V three phase transformer system is converted into a Δ-Δ system, increase in capacity of the system is (A) 86.6% (B) 50% (C) 57.7% (D) 73.2%

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When a V-V three phase transformer system is converted into a Δ-Δ system, increase in capacity of the system is 73.2%

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The power factor of a single phase load can be calculated if the instruments available are three ammeters or three voltmeters.

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The two pressure coils of a single phase power factor meter have the same dimensions and the same number of turns.

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For handling greater currents induction wattmeters are used in conjunction with current transformers.

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Why is a capacitor used in a single phase motor and not in three phase motor ?

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In 1-phase induction motor capacitor work is generate the auxiliary winding current than excite the main winding to rotor starts rotate. After rotor start rotating about 75% of their speed than auxiliary ... emf to start the motor.so,in 3-phase induction motor is self start induction motor.

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A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is (A) 216 V (B) 226 V (C) 234 V (D) 236 V

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A 230 V/460 V single-phase transformer operating at 20 A and unity power factor has primary referred resistance of 0.2 Ω and reactance of 0.5 Ω. The approximate primary induced emf is 226 V

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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

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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

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What are the five types of single phase motors used in the industry?

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Explain construction and working of single phase Auto transformer.

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Construction of single phase auto transformer: (i) It has only one winding wound on a laminated circular magnetic core. (ii) The core is made of silicon steel stampings. (iii) The two terminals of the ... help of handle. 5) The same transformer can be used as step-up or step down auto-transformer

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Impedance relays are used for phase faults on long line.

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The thickness of laminations used in a transformer is usually 0.4 mm to 0.5 mm.

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The chemical used in breather for transformer should have the quality of cleansing the transformer oil.

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The core used in high frequency transformer is usually air core .

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Give the operation of single phase full wave bridge controlled converter with RL load with a neat diagram. Also draw its waveform.

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Single phase fully control bridge converter with RL load: 1. During positive half cycle of input voltage, T1 and T2 are forward biased and during negative half cycle, T3 and T4 are forward biased. Therefore, T1-T2 ... cycle till the firing of next pair of SCRs as shown in the waveform.

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With a neat sketch explain working of 1 phase dynamometer type power factor meter.

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Working of 1 phase dynamometer type power factor meter : The current coil is connected in series with load. Two pressure coils marked as A and B are connected across the supply terminals ... becomes stationary and the pointer shows steady deflection corresponding to the power factor of the load. 

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A single core cable is designed to work for a single phase system with a peak voltage of 220 kV. The maximum permissible stress in the dielectric is not to exceed 20 kV/mm. For economical size, the overall core diameter of the cable is (A) 28.2 mm (B) 26.4 mm (C) 24.4 mm (D) 22.0 mm

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A single core cable is designed to work for a single phase system with a peak voltage of 220 kV. The maximum permissible stress in the dielectric is not to exceed 20 kV/mm. For economical size, the overall core diameter of the cable is 22.0 mm

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A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will?

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A capacitor-start single phase induction motor is switched on to supply with its capacitor replaced by an inductor of equivalent reactance value. It will not start at all.

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The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be?

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The running winding of a single phase motor on testing with meggar is found to be ground. Most probable location of the ground will be at the slot edge where coil enters or comes out of the slot.

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Explain MCB and ELCB with connection diagram supplying single phase load. 

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OR OR Explanation: * MCB provides short circuit protection. * MCB provides overload protection * ELCB provides earth fault protection. * MCB is in series with ... occurs, the ELCB cuts off the power within the time of 0.1 sec. automatically to protect the personnel. 

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Explain with neat circuit diagrams the procedures to perform no load and blocked rotor tests on three phase induction motor.

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Describe with neat diagram phase sequence indicator.

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Phase Sequence Indicator: There are two types of phase sequence indicators: (a) Rotating type phase sequence indicator (b) Static type phase sequence indicator (a) Rotating Type Phase Sequence ... of the supply is reversed or altered, then the lamp 1 will glow brighter than the lamp 2.

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Define phase sequence of three phase supply with waveforms. What is normal phase sequence? Which 3 standard colours are used to denote the phase sequence?

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It  is  sunnosoidal  sequence.

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Explain the principle of ON-OFF control and phase control of AC voltage controller with suitable circuit and waveforms.

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The integral cycle control (on-off control) and phase angle control are the two types of AC voltage controller. The principle of ON-OFF control: The on-off control is also called an integral cycle ... control. In phase control, the switch is on for some period of each cycle.  

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State the four major parts of Transformer and material used for their construction.

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IDMT relays are used to protect the transformer against :  (A) Internal short -circuits (B) Open circuits (C) External short circuits (D) Oil leakage

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IDMT relays are used to protect the transformer against : External short circuits

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

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Material used for construction of transformer core is usually silicon steel.

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Explain the electrical losses of magnetic materials used for the cores of inductors and transformer.

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Reduction in core losses and increase in permeability are obtained with transformer employing?

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Reduction in core losses and increase in permeability are obtained with transformer employing core built-up of laminations of cold rolled grain oriented steel.

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Why does a transformer only work with an AC supply?

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The transformer work depends on the induction as main principle ,for that AC is the right means

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Write selection criteria of distribution transformer with any four points.

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Selection Criteria for Distribution Transformer:  i) Ratings - The kVA ratings should comply with IS:2026 ( Part l )-1977*. The noload secondary voltage should be 433 volts for transformers to be ... is not necessary. vi) Cooling - The transformers covered in this group are generally ONAN, AN

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Which of the following is true with an auto transformer? A) It has only one winding  B) It has two separate windings namely primary winding and secondary winding C) It has two primary windings and one single secondary winding D) None of these

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Which of the following is true with an auto transformer? A) It has only one winding  B) It has two separate windings namely primary winding and secondary winding C) It has two primary windings and one single secondary winding D) None of these

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To protect the power transformer (Y-Y with neutral grounded) against fault, what type of connection do the CTs have ?

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To protect the power transformer (Y-Y with neutral grounded) against fault, what type of connection do the CTs have ? Δ-Δ connection

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In a 3-phase converter circuit during commutation when one SCR in one phase is turned on to turn-off an SCR in another phase, results in (A) voltage notching (B) harmonic distortion (C) voltage sag (D) voltage swell

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In a 3-phase converter circuit during commutation when one SCR in one phase is turned on to turn-off an SCR in another phase, results in voltage notching

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The disc of a single phase Induction-type energy meter makes 60 revolutions in 6 minutes. Meter Constant is 1200 rev/kWh. Power consumption in the load is (A) 1.2 kW (B) 1 kW (C) 600 W (D) 500 W

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The disc of a single phase Induction-type energy meter makes 60 revolutions in 6 minutes. Meter Constant is 1200 rev/kWh. Power consumption in the load is 500 W

Description :

In a three-phase supply floating neutral is undesirable because it way give rise to?

Answer :

In a three-phase supply floating neutral is undesirable because it way give rise to unequal line voltages across the load.

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