In the circuit shown,  and . It is supplied by a three phase  source with the phase sequence being R-Y-B. Assume the watt meters  and  to be ideal. The magnitude of the difference between the readings of  and  in watts is _______ (rounded off to 2 decimal places).

A 3-phase, star-connected, balanced load is supplied from a 3-phase,  (rms), balanced voltage source with phase sequence R-Y-B, as shown in the figure. If the wattmeter reading is  and the line current is  (rms), then the power factor of the load per phase is

Two wattmeter method is used for measurement of power in a balanced three-phase load supplied from a balanced three-phase system. If one of the watt-meters reads half of the other (both positive), then the power factor of the load is  

The load shown in the figure is supplied by a 400 V (line-to-line), 3-phase source (RYB sequence). The load is balanced and inductive, drawing 3464 VA. When the switch S is in position N, the three watt-meters  read 577.35 W each. If the switch is moved to position Y, the readings of the watt-meters in watts will be:

A 3-phase balanced load which has a power factor of 0.707 is connected to a balanced supply. The power consumed by the load is 5kW. The power is measured by the two-wattmeter method. The reading of the two watt meters are

The coils of a wattmeter have resistance 0.01 and 1000; their inductances may be neglected. The wattmeter is connected as shown in the figure, to measure the power consumed by a load, which draws 25 A at power factor 0.8. The voltage across the load terminals is 30 V. The percentage error on the wattmeter reading is __________.

Power consumed by a balanced 3 – phase, 3 – wire load is measured by the two wattmeter method. The first wattmeter reads twice that of the second. Then the load impedance angle in radians is

While measuring power of a three-phase balanced load by the two-wattmeter method, the readings are 100W and 250W. The power factor of the load is_____________.

An LPF wattmeter of power factor 0.2 is having three voltage settings 300V, 150V and 75V, and two current settings 5A and 10A. The full scale reading is 150. If the wattmeter is used with 150V voltage setting and 10A current setting, the multiplying factor of the wattmeter is______________.

For the circuit shown in the figure, the voltage and current expression are  and

The average power measured by the wattmeter is

Consider the following statements:

(i) The compensating coil of a low power factor wattmeter compensates the effect of the impedance of the current coil.

(ii) The compensating coil of a low power factor wattmeter compensates the effect of the impedance of the voltage coil circuit.

A wattmeter is connected as shown in the figure. The wattmeter reads

The figure shows a three-phase delta connected load supplied from a 400V, 50 Hz, 3-phase balanced source. The pressure coil (PC) and current coil (CC) of a wattmeter are connected to the load as shown, with the coil polarities suitably selected to ensure a positive deflection. The wattmeter reading will be

A sampling wattmeter (that computes power from simultaneously sampled values of voltage and current) is used to measure the average power of a load. The peak to peak voltage of the square wave is 10 V and the current is a triangular wave of 5A p-p as shown in the figure. The period is 20ms.  The reading in W will be

Two wattmeters, which are connected to measure the total power on a three phase system supplying a balanced load, read 10.5 kW and -2.5 kW, respectively. The total power and the power factor, respectively, are

The circuit in figure is used to measure the power consumed by the load. The current coil and the voltage coil of the wattmeter have 0.02Ω and 1000Ω resistances respectively. The measured power compared to the load power will be

A single-phase load is connected between R and Y terminals of a 415 V, symmetrical, 3-phase, 4-wire system with phase sequence RYB. A wattmeter is connected in the system as shown in figure. The power factor of the load is 0.8 lagging. The wattmeter will read

A wattmeter reads 400 W when its current coil is connected in the R phase and its pressure coil is  connected between this phase and the neutral of asymmetrical 3-phase system supplying a balanced star connected 0.8p.f. inductive load. The phase sequence is RYB. What will be the reading of this wattmeter if its pressure coil alone is reconnected between the B and Y phases all other connections remaining as before

The line-to-line input voltage to the 3 phase, 50 Hz, ac circuit shown in figure is 100 V rms. Assuming that the phase sequence is RYB, the watt-meters would read.

The minimum number of wattmeter (s) required to measure 3-phase, 3-wire balanced or unbalanced power is

The two wattmeter method is used to measure active power on a three phase, three wire system. If the phase voltage is unbalanced, then the power reading is:

A three-phase load operates with balanced voltages applied to its terminals, and draws balanced currents. The potential coil of a moving coil wattmeter is connected from R to Y terminals of the load. The current coil of the meter is connected in series with phase B. Then the quantity indicated by this wattmeter is proportional

A dynamometer type wattmeter responds to the

The moving coil in a dynamometer wattmeter is connected

A symmetrical star connected three-phase load is made of three identical coils having an internal resistance of 12 Ohm and inductance of 142mH. The power taken by this load when connected to a balanced three-phase three-wire supply of 400V, 50Hz is measured using the two wattmeter method. The watt meters used are similar and are of type of 400V, 5A, UPF, class 1 accuracy.

,  and  are the balanced instantaneous line to neutral voltages and ,  and  are instantaneous line currents in a balanced three phase circuit, the computation  will yield a quantity proportional to?

Two identical watt-meters are connected to measure power in a 3-phase 3-wire balanced load. What is the load power factor if

(a)

(b) Either  is zero ____________