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In a power or distribution transformer about 10 percent end turns are heavily insulated to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns.

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Answer : The transformer laminations are insulated from each other by thin coat of varnish.

Answer : High voltage winding in a transformer has more number of turns.

Description : Increasing the number of turns of wire on the secondary of a transformer will  (A) Decrease the secondary current (B) Increase the primary current (C) Have no effect on the secondary current (D) Increase the secondary current

Answer : Increasing the number of turns of wire on the secondary of a transformer will Decrease the secondary current 

Answer : yes High Voltage side of Transformer winding have more number of turns. and low voltage side of Transformer winding have less number of turns.

Description : Write selection criteria of distribution transformer with any four points.

Answer : 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

Answer : In a distribution system, in order to improve power factor, the synchronous capacitors are installed at the receiving end.

Answer : The power transformer is a constant main flux device.

Description : The maximum load that a power transformer can carry is limited by its?

Answer : The maximum load that a power transformer can carry is limited by its voltage ratio.

Description : lt the length, number of turns and area of a coil are  doubled, the inductance of the coil

Answer : lt the length, number of turns and area of a coil are  doubled, the inductance of the coil is quadrupled

Description : Turns ratio

Answer : Turns ratio formula

Description : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage:  (A) Eddy Current and Hysteresis losses will be ... Current will be too much high  (C) Transformer may start to smoke and burn  (D) No effect

Answer : What would happen if a power transformer designed for operation on 50 Hz (frequency) were connected to a 500 Hz (frequency) source of the same voltage:  (A) Eddy Current and Hysteresis losses will be ... will be too much high  (C) Transformer may start to smoke and burn  (D) No effect

Description : A transformer has negative voltage regulation when its load power factor is   (1) Zero (2) Unity (3) Leading (4) Lagging

Answer : Leading

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

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

Description : Explain transformer isolated drive circuits providing both signal and power.

Answer : The maximum efficiency of a distribution transformer is at 50% full load.

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

Answer : A transformer cannot raise or lower the voltage of a D.C. supply because Faraday's laws of electromagnetic induction are not valid since the rate of change of flux is zero.

Answer : The efficiency of a power transformer is of the order of 98 percent.

Description : State the losses in secondary distribution system. 

Answer : The losses in secondary distribution system: a) Technical losses: 1. Due to poor voltage 2. Due to unbalance load 3. Due poor quality of transformer & its components 4. Due to poor quality ... of induction type of energy meter. 3. Lack of administration. 4. Energy theft 5. Unmetered supply

Description : Explain following techniques related to energy conservation in transmission and distribution system. (i) By balancing phase currents (ii) Variable technical losses (I2R losses).

Answer : (i) Balancing Phase currents: Proper (healthy balanced) three phase loads always draw equal currents in all lines but single phase loads in the 3 phase 4 wire system or loads connected between two ... . 11) Minimize I2R losses. 12) Balance the load currents. 13) Regulate the system voltages.

Description : The permissible voltage variation in transmission and distribution system is:  (A) ± 0.1% (B) ± 1% (C) ±10% (D) ± 25%

Answer : The permissible voltage variation in transmission and distribution system is: ±10%

Description : The skin effect in conductors is due to non uniform distribution of current in it and major portion of current is near the _______ of conductor.  (1) Surface (2) Center (3) Complete cross section area (4) Axis

Answer : The skin effect in conductors is due to non uniform distribution of current in it and major portion of current is near the Surface of conductor. 

Description : Grid distribution system

Answer : Grid distribution system:-  In this system, when the feeder or loop or ring is charged (energized) by two or more than two substations from two or more than two different generating stations then it is known as “Grid distribution system. In this system only one feeder is utilized at a time. 

Description : Define: primary and secondary distribution system 

Answer : i) Primary Distribution:  It is a 3-phase, 3-wire transmission line connected in between receiving substation to Distribution substation. OR It is link between receiving substation & ... substation to consumer line. OR It is link between distribution transformer substation & consumer. 

Description : State the condition for selecting site for distribution substation. 

Answer : Following condition should be considered while selecting site for distribution sub-station:-  1. Near load center :  Sub-station should be located near load center to reduce cost of Transmission and ... free from earthquake :  To avoid damage to sub-station area should be free earth quake. 

Description : State the classification of distribution substation. 

Answer : The classification of distribution substation. 1. Pole mounted distribution substation 2. Plinth mounted distribution substation 3. Compact/prefabricated distribution substation 4. ... Indoor distribution substation 6. Outdoor distribution substation 7. Mobile distribution substation 

Description : Advantages of Grid distribution scheme

Answer : Advantages of Grid distribution scheme 1. Supply to distribution transformer center is given through two different generating stations or major generating stations 2. It has highest reliability to ... highest reliability to maintain supply even when there was maintenance on any one feeder. 

Description :  different types of distribution scheme.  

Answer : According to scheme of connection: -  a) Radial (Tree) distribution system  b) Ring mains (Loop) distribution system  c) Grid (interconnected) distribution system OR Types of ... distribution system  b) Ring mains (Loop) distribution system  c) Grid (interconnected) distribution system

Description : comparison between Feeder and Distribution

Answer : Sr.No Feeder Distributor 1 It is link between receiving substation & distribution transformer   It is link between distribution transformer substation & consumer  2 ... loading point is at substation only   Distributors loading point is throughout its length. 

Description : requirements of a distribution system

Answer : Following requirements of a distribution system.  1. Layout should be simple in design. 2. It should have less initial cost 3. The distribution system should have minimum distribution ... stability of existing distribution system. 15. Time required for completion of work should be less. 

Description : Why radial distribution system used for short distance ? 

Answer : Because of following disadvantages radial distribution system is not used for long distance:  Since there is only one feeder to DTC feed at one point so, 1) There is no reliability ... more time for fault finding & repairing Hence radial distribution system is used for short distance.

Description : Explain with schematic diagram direct distribution of solar energy.

Answer : Explain with schematic diagram direct distribution of solar energy: Solar energy reaching earth's surface consists of two components: i) Direct solar energy, ii) Diffused solar energy. Direct solar energy ... radiation. It is very intense radiation and it can produce sun burns and shadows.

Description : The main criterion for selection of the size of a radial distribution system is

Answer : The main criterion for selection of the size of a radial distribution system is voltage drop

Description : Precise control of reactive current flow entering the transmission and distribution systems can be minimized by using (A) synchronous condenser (B) static VAR capacitor (C) capacitor bank (D) thyristor switched reactor in parallel with capacitor

Answer : Precise control of reactive current flow entering the transmission and distribution systems can be minimized by using (A) synchronous condenser (B) static VAR capacitor (C) capacitor bank (D) thyristor switched reactor in parallel with capacitor

Answer : Service mains are the conductors, which connect the consumer's terminals to the distribution.

Description : A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts applied to the primary. What is the voltage across the secondary?  (A) 30 Volts (B) 480 Volts (C) 120 Volts (D) 60 Volts

Answer : A certain transformer has 200 turns in the primary winding, 50 turns in the secondary winding and 120 volts applied to the primary. What is the voltage across the secondary?  (A) 30 Volts (B) 480 Volts (C) 120 Volts (D) 60 Volts

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

Answer : The transformer ratings are usually expressed in terms of kVA.

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

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

Description : In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are?

Answer : In a given transformer for a given applied voltage, losses which remain constant irrespective of load changes are hysteresis and eddy current losses.

Answer : No-load current in a transformer lags behind the voltage by about 75°.

Answer : The purpose of providing an iron core in a transformer is to decrease the reluctance of the magnetic path.

Answer : In the transformer low voltage winding has got more cross-sectional area.

Answer : In a transformer, routine efficiency depends upon load current and power factor of load.

Answer : Transformer breaths in when load on it decreases.

Answer : The purpose of providing iron core in a step-up transformer is to decrease the magnitude of magnetizing current.

Answer : The use of higher flux density in the transformer design reduces weight per kVA.

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

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

Answer : conservator or a reservoir tank for insulating oil in transformer which used for balanced the onload oil level with help of oil level indicator which mount on middle part of reservoir tank.

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