Recent questions tagged wattmeter

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

Last 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.

Description : State the principle of wattmeter. 

Last 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. 

Description : Merits of two wattmeter method

Last 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.

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

Last 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. 

Description : State any four errors that occur in dynamometer type wattmeter

Last 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

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

Last 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

Description : With neat diagram explain constructional details of dynamometer type wattmeter.

Last 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. 

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

Last 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.

Description : State various types of errors in wattmeter.

Last 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.

Description : Explain construction & working of electrodynamometer type wattmeter.

Last 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.

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

Last 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.

Description : List one advantage and one disadvantage of one wattmeter method. 

Last 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. 

Description : The torque produced in wattmeter is proportional to

Last Answer : A

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%

Last 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%

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?

Last 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.

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?

Last 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.

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

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

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

Last Answer : An induction wattmeter can be used for A.C. 

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

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