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An induction wattmeter can be used for A.C. 

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Answer :

A dynamometer wattmeter can be used for both D.C. and A.C.

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217 views 1 answer
Description :

An induction type energy meter is found to run fast. Correction for this error can be made by  (A) Over-load compensation. (B) Voltage compensation. (C) Moving the brake magnet away from the centre of the disc. (D) Moving the brake magnet towards the centre of the disc.

Answer :

An induction type energy meter is found to run fast. Correction for this error can be made by Moving the brake magnet away from the centre of the disc.

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112 views 1 answer
Description :

Answer :

The pressure coil of a wattmeter should be connected on the supply side of the current coil when load impedance is high.

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Description :

Answer :

The resistance in the circuit of the moving coil of a dynamometer wattmeter should be high.

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Description :

The torque produced in wattmeter is proportional to

Answer :

A

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688 views 2 answers
Description :

In a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be?

Answer :

In a 3-phase power measurement by two wattmeter method the reading of one of the wattmeter was zero. The power factor of the load must be 0.5.

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201 views 1 answer
Description :

In a 3-phase power measurement by two wattmeter method, both the watt meters had identical readings. The power factor of the load was?

Answer :

In a 3-phase power measurement by two wattmeter method, both the watt meters had identical readings. The power factor of the load was unity.

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699 views 1 answer
Description :

Answer :

In a low power factor wattmeter the compensating coil is connected in series with pressure coil.

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341 views 1 answer
Description :

Answer :

In a low power factor wattmeter the pressure coil is connected to the load side of the current coil.

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177 views 1 answer
Description :

Answer :

An induction meter can handle current up to 100 A.

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Description :

Answer :

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

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Description :

Answer :

if induction motor rotates exceed than its synchronous speed, it acts as a generator.

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54 views 1 answer
Description :

List the different errors in wattmeter & explain compensation for it.

Answer :

Errors in Wattmeter Compensation method Error due to connection method To overcome this error, wattmeters are provided with additional compensating winding which is connected in series with ... due to friction The weight of moving system be reduced to minimum possible.

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6.0k views 1 answer
Description :

Use Voltmeter, ammeter, wattmeter to determine active, reactive and apparent power consumed in given R-L series circuit, draw phasor diagram.

Answer :

Practical Significance In the industry environment Electrical Engineering diploma graduate are expected to measure basic parameters like voltage, frequency, time period etc. for R-L series circuits. Therefore ... /varying L. 7. Draw the phasor diagram for each of reading for verification.

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76 views 1 answer
Description :

State the principle of wattmeter. 

Answer :

Working Principle of Wattmeter: It consists of two stationary coils, called current coils and one moving coil, called voltage or potential coil. The current coils are connected such that they ... experiences a force and tends to move in the direction as per Fleming's left hand rule. 

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137 views 1 answer
Description :

Merits of two wattmeter method

Answer :

Advantages of Two Wattmeter Method for 3-Phase Power Measurement: 1) It is used for balanced as well as unbalanced load. 2) For the star type load, it is not necessary to ... reactive volt-amperes for balanced loads also. 7) The circuit connections are independent of load connection.

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83 views 2 answers
Description :

State the effects of errors in dynamometer type wattmeter due to i) pc- inductance ii) pc- capacitance iii) mutual inductance iv) Connection.

Answer :

Errors in wattmeter:  i) pc - inductance: Pressure coil inductance causes wattmeter to read more power than actual .  ii) pc-capacitance: The wattmeter reads less power.  iii) ... iv) Connection: In uncompensated wattmeter , the reading of wattmeter includes the powerloss in coils. 

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86 views 1 answer
Description :

State any four errors that occur in dynamometer type wattmeter

Answer :

Errors that occur in dynamometer type wattmeter: 1. Errors due to method of connection. 2. Error due to pressure coil inductance. 3. Error due to pressure coil Capacitance. 4. Error due to mutual ... Error due to eddy currents. 7. Temperature error. 8. Error due to vibration of moving system

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173 views 1 answer
Description :

Compare CC and PC of wattmeter on the basis of:- (i) Connection (ii) Status (iii) Number of turns (iv) Gauge of wire.

Answer :

Particulars Current coil (CC) Pressure coil (PC) Connection Connected in series with load Connected in parallel with load Status It is fixed coil in wattmeter It is moving coil in ... number of turns It is having more number of turns Gauge of wire Less More

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257 views 1 answer
Description :

With neat diagram explain constructional details of dynamometer type wattmeter.

Answer :

Working Principle of Wattmeter: It consists of two stationary coils, called current coils and one moving coil, called voltage or potential coil. The moving coil is mounted on the spindle, in the gap ... experiences a force and tends to move in the direction as per Fleming's left hand rule. 

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171 views 3 answers
Description :

State any two disadvantages of one wattmeter method of measurement of 3 phase power.

Answer :

State any two disadvantages of one wattmeter method of measurement of 3 phase power. Disadvantages of one wattmeter method:- 1. Only used for balanced load 2. It can not be used for ... connection then neutral point must be available 4. Delta connection must be opened to connect current coil.

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1.4k views 1 answer
Description :

State various types of errors in wattmeter.

Answer :

Types of Error in wattmeter: 1. Errors due to method of connection. 2. Error due to pressure coil inductance. 3. Error due to pressure coil Capacitance. 4. Error due to mutual inductance effect. 5. ... . Error due to eddy currents. 7. Temperature error. 8. Error due to vibration of moving system.

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81 views 1 answer
Description :

Explain construction & working of electrodynamometer type wattmeter.

Answer :

Electrodynamometer Type Wattmeter:  Construction: It essentially consists of the fixed and moving coil. The fixed coil is split into two equal parts which are placed close together and parallel to each other. ... hence these instruments can be used for measurement of A.C. & D.C. power.

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738 views 1 answer
Description :

List one advantage and one disadvantage of one wattmeter method. 

Answer :

Advantages:  1) Only one wattmeter is used.  2) Less number of connections.  3) Cost required is less.  Disadvantages:  1) Used only for 3- Φ balanced load and not for ... be accessible for connecting the Pressure coil.  3) Delta connection must be opened to connect current coil. 

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828 views 1 answer
Description :

The potential coil of a single phase dynamometer wattmeter has 4840 Ohm resistance. Voltage across the load is 220 V. With the potential coil connected on the load side, the meter indicates 100 W. Approximate percentage error due to wattmeter connection is (A) 11% (B) 9% (C) 1.1% (D) 3%

Answer :

The potential coil of a single phase dynamometer wattmeter has 4840 Ohm resistance. Voltage across the load is 220 V. With the potential coil connected on the load side, the meter indicates 100 W. Approximate percentage error due to wattmeter connection is 11%

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279 views 1 answer
Description :

Answer :

Yes, Induction heating is used for both magnetic and non-magnetic materials.

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87 views 1 answer
Description :

The synchronous speed of an 8 pole induction motor supplied power from a 50 Hz source will be ?

Answer :

Ns         equals        f/pair pole 50/4      - 12.5

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136 views 2 answers
Description :

State starters used for i) 3-Ph squirrel cage induction motor (3HP) ii) D.C. motor 

Answer :

Name the starters used for following motors : i) 3 H.P. 3-Ph squirrel cage I.M: i) DOL starter OR ii) Star-Delta Starter OR ii) Auto transformer starter OR iii) Soft start starter.  ii) D.C Shunt Motor : 1) Armature resistance starter (Three Point Starter) OR 2) Four Point Starter 

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125 views 1 answer
Description :

Answer :

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

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281 views 1 answer
Description :

Why starter is required for starting an induction motor?

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102 views 0 answers
Description :

how can we reverse the direction of rotation of three phase induction motor ?

Answer :

The direction of rotation of three phase induction motor can be reversed by plugging i.e by changing any two out of three phases of the supply to the stator of the Induction motor terminal.

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108 views 1 answer
Description :

State the function and shape of following parts used in induction type energy meter: i) Series magnet ii) Shunt magnet iii) Al disc iv) Brake magnet

Answer :

i) Series magnet: produce flux proportional to current (load current) of circuit and interact in the aluminum disc with flux produced by voltage magnet for torque production. Its shape is like letter U.  ii) ... : brakes the motion of the aluminum disc or slows it down. Its shape is like letter C. 

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80 views 1 answer
Description :

The range of frequencies used in induction heating is :  (A) 0-25 Hz  (C) less than 200 Hz  (B) 50 to 100 Hz  (D) more than 1 kHz

Answer :

The range of frequencies used in induction heating is : more than 1 kHz

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76 views 1 answer
Description :

Answer :

The repulsion-start induction-run motor is used because of high starting torque.

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66 views 1 answer
Description :

The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be

Answer :

The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be 0.5 Ohm

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133 views 1 answer
Description :

The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be?

Answer :

The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be 4.

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80 views 1 answer
Description :

A change of 4% in the supply voltage to an induction motor will produce a change of approximately

Answer :

A change of 4% in the supply voltage to an induction motor will produce a change of approximately 8% in the rotor torque

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296 views 1 answer
Description :

In an induction motor if the flux density is reduced to one-half, of its normal value then the torque will  (1) reduce to one-half (2) reduce to one-fourth (3) remain unchanged (4) increase four times

Answer :

In an induction motor if the flux density is reduced.to one-half, of its normal value then the torque will reduce to one-fourth

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245 views 1 answer
Description :

An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is (A) 5.06 kW (B) 0.3 kW (C) 100 kW (D) 83.33 kW

Answer :

An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is 83.33 kW

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143 views 1 answer
Description :

In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is (A) 0.2 Ω (B) 0.3 Ω (C) 0.4 Ω (D) 0.5 Ω

Answer :

In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is 0.3 Ω

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111 views 1 answer
Description :

Answer :

The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it helps in reducing the tendency of the rotor teeth to remain under the stator teeth.

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124 views 1 answer
Description :

A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?

Answer :

A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because stator supply is not required to produce magnetic field.

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93 views 1 answer
Description :

Answer :

An induction motor has relatively high power factor at near full load.

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67 views 1 answer
Description :

Consider the following statements with regard to induction type wattmeter :  1. Can be used on both ac and dc systems.  2. Power consumption is relatively low.  3. It is accurate only at stated frequency and temperature.  Which of the above statements is/are correct ?  (a) 1 only (b) 2 only (c) 3 only (d) 1, 2 and 3

Answer :

Consider the following statements with regard to induction type wattmeter :  1. Can be used on both ac and dc systems.  2. Power consumption is relatively low.  3. It is accurate only at stated frequency and temperature. ... correct ?  (a) 1 only (b) 2 only (c) 3 only (d) 1, 2 and 3

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147 views 1 answer
Description :

Explain energy conservation technique “by improving power quality” for induction motor.

Answer :

Energy conservation method in induction motor by improving power quality: Electrical energy can be conserved by improving the power quality. It can be achieved by avoiding voltage unbalance, maintaining ... losses can be minimized by using harmonic filter thus reducing the harmonics in the system.

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3.0k views 2 answers
Description :

List any four errors in induction type energy meter. Give method of compensation for each.

Answer :

Errors in Induction Type Energy Meter with their Compensation:  1) Error due to friction: This error can be compensated by the additional shading band provided on the shunt electromagnet.  2) Phase ... error: This error can be compensated by providing a flux diverter' to the current magnet. 

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997 views 1 answer
Description :

A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for

Answer :

A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for 4 poles

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157 views 1 answer
Description :

Explain the working principle of induction motor. 

Answer :

Working principle of induction motor: * When the motor is excited with three-phase supply, three-phase stator winding carries three-phase currents & produces a rotating magnetic field of constant magnitude and ... , which tend to move the rotor in the same direction as the rotating magnetic field. 

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82 views 1 answer
Description :

Explain the activities carried out during weekly maintenance of 3 ph. Induction motor. 

Answer :

Activities Carried out During Weekly Maintenance of 3 ph. Induction Motor:  1) Check belt tension. In cases where this is excessive it should immediately be reduces and in the case of sleeve ... and cooled by oil mist systems its important to check the oil mist flow paths/pressure components.

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89 views 1 answer
Description :

State the function of following parts in Induction motor. (i) Stator (ii) Slip rings

Answer :

Name of part Function Stator 1) Stator frame supports the core, terminal box and protects the inner parts. 2) Stator core houses stator winding. 3) Stator winding ... ) Provides facility to connect external resistance to rotor circuit through brushes for starting and control.

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72 views 1 answer
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