# The current coil of a wattmeter is connected to the CT of R-phase....

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The current coil of a wattmeter is connected to the CT of R-phase. The potential coil is connected across Y and B phases. The wattmeter measures

The current coil of a wattmeter is connected to the CT of R-phase. The potential coil is connected across Y and B phases. The wattmeter measures Reactive power of R phase.

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The current coil of a wattmeter is connected to the C.T. of R phase. Its potential coil is connected across Y & B phases. The wattmeter measures (a) active power in R phase (b) active power of Y-phase (c) reactive power in R-phase (d) power proportional to 3-phase power if the load is balanced

Two wattmeter method is employed to measure power in a 3 -phase balanced system with the current coil connected in the A and C lines. The phase sequence is ABC. If the wattmeter with its current coil in A -phase line reads zero, then the power factor of the 3 -phase load will be

A two-phase generator is connected to two 90Ω load resistors. Each coil generates 120 V ac. The value of current flowing through the common neutral line will be: A. 1.33 A B. 1.88 A C. 2.66 A D. 1.77 A

A coil having 90 turns is connected to a 120 V, 60 Hz source. If the effective value of the magnetizing current is 4 A. Calculate the inductance of the coil.  (A) 79.6 mH (B) 121.2 mH (C) 32.2 mH (D) 83.16 mH

A series R-L circuit is suddenly connected to d.c. voltage source of V volts. The current in this series circuit, just after the switch is closed, is equal to (1) Zero (2) V/L (3) V/C (4) V.L/C

When a resistor R is connected to a current source, it consumes a power of 18 W. When the same R is connected to a voltage source having the same magnitude as the current source, the power absorbed by R is 4.5 W. The magnitude of the current source and the value of R are  (A) √18A and 1Ω (B) 3A and 2Ω (C) 1A and 18Ω (D) 6A and 0.5Ω

The pressure coil of a dynamometer type wattmeter is  A) Highly inductive B) Highly resistive C) Purely resistive D) Purely inductive

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%

A dynamometer type wattmeter with its voltage coil connected across the load side of instrument reads 250 W. If the load voltage be 200 V, what power is being taken by load? The voltage coil has resistance of 2000 Ω. (1) 200 W (2) 215W (3) 230 W /(4) 245 W

A balanced Delta connected load supplied with 440 V 50 Hz three phase AC supply has R=10 Ohm and L=0.6 mH in is each arm. Calculate line and phase current, active power.

The minimum number of wattmeter(s) required to measure 3-phase, 3-wire balanced or unbalanced power is  A) 1 B) 2 C) 3 D) 4

Consider the following statements  1) 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) (i) is true but (ii) is false B) (i) is false but (ii) is true C) Both (i) and (ii) are true D) Both (i) and (ii) are false

In dynamometer type of wattmeter, which of the coil is split up into two parts?

A 750 Hp, 250 V, 1200 r/min DC motor is connected to a 208 V, 3 phase, 60 Hz, line using a 3 phase bridge converter. The full load armature current is 2500 A and the armature resistance is 4 m ohm. Calculate the required firing angle under rated full load conditions.  (A) 45 deg (B) 208 deg (C) 27 deg (D) 32 deg

If a dynamometer wattmeter is connected in an ac circuit, the power indicated by the wattmeter will be (a) volt-ampere product (b) average power (c) peak power (d) instantaneous power

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

In an R-C phase shift oscillator, the minimum no. of R-C networks to be connected in cascade will be -

An R-L series AC circuit has R = 10 ohm and XL = 10 ohm. It is connected to an AC voltage source, the phase angle between voltage and current is (a) 30° (b) 45° (c) 60° (d) 36.8°

The magnetic field intensity at the centre of a current carrying coil of diameter J m is K. The current flowing in the coil is

The sequence components of current of a single-phase load connected to a 3-phase system are (A) equal positive and negative sequence components (B) equal positive, negative and zero sequence components (C) vector sum of sequence currents is zero (D) algebraic sum of sequence currents is zero

In the measurement of power of balanced load by two wattmeter method in a 3-phase circuit, The readings of the wattmeters are 4 kW and 2 kW respectively, the later is being taken after reversing the connections of current coil. the power factor and reactive power of the load is A) 0.2 & 6 kVAR B) 0.2 & 6 √3 kVAR C) 0.32 & 2 kVAR D) 0.32 & 2 √3 kVAR

While measuring power in a three phase load by two wattmeter method, the reading of two wattmeter are equal and opposite, when (a) load is balanced (b) power factor is unity (c) phase angle is between 60° to 90° (d) the load is purely inductive

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?

The current coil of a single-phase energy meter is wound on (a) One limb of the laminated core (b) Both the limbs of the laminated core with same number of turns (c) Both the limbs of the laminated core with different number of turns (d) The centre of the limb on the laminated core

The primary coil of a transformer is connected to a 60 V ac source. The secondary coil is connected to a 330 ohms load. The turns ratio is 3:1. What is the secondary voltage? A.2 V B.20 V C.180 V D.18 V

Measurement of power and power factor of a 3-phase system by two wattmeter method can be obtained in case of  1. Balanced load and balanced source  2. Balanced source with 3-phase 3-wire unbalanced load  3. Unbalanced source with 3-phase 3-wire balanced load  4. Balanced source with 3-phase 4-wire unbalanced load  5. unbalanced and unbalanced source    (a) 1 only (b) 2, 3 and 5 (c) 1, 2, 3, 4 and 5 (d) 1, 2, 3 and 5

Moving coil in dynamometer wattmeter connected : - a) in series with fixed coil b) across supply c) in series with load d) across load

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

The ammeter reading connected across a CT secondary is 3 A and the voltage reading connected across a PT is 90 V. If the specification of the CT and PT are respectively 1000 A/5 A and 6.6 kV/110 V, What is the actual current and voltage of the line?

The current in a 200 mH coil increases from 2 to 5 A in 0.1 Second. What is rate of change of current? A. 30 A/s B. 20 A/s C. 10 A/s D. none of these

A step voltage E is applied to a series R-L circuit. The rate of change of current is maximum at t = _:  (1) Zero (2) Infinity (3) L/R (4) R/L

The r.m.s. value of a sinusoidal A.C. current is equal to its value at an angle of______degrees.

For power measurement of three phase circuit by two wattmeter method, when the value of power factor is less than 0.5 lagging:

The power consumed by a coil is 300 W when connected to a 30 V dc source and 108 W when connected to a 30 V ac source. The reactance of the coil is

The voltage induced across a certain coil is 200 mV. A 1200 resistor is connected to the coil terminals. The induced current will be: A. 1.7 mA B. 16 mA C. 12 mA D. 120 mA

The power delivered to a three-phase load can be measured by the use of 2 wattmeter only when the A. Load is balanced B. 3 -phase load is connected to the source through 3 wires C. Load is unbalanced D. 3 -phase load is connected to the source through 4 wires

If the fault current is 6000 A, the relay plug setting is 150% and the CT ratio is 400/5, the plug setting multiplier will be

If the fault current is 2000 A, the relay setting is 50% and CT ratio is 400:5, the plug setting multiplier will be

A PMMC instrument has FSD of 100 μA and a coil resistance of 1 kΩ. To convert the instrument into an ammeter with full scale deflection of 100 mA, the required shunt resistance is (A) 1 Ω (B) 1.001 Ω (C) 0.5 Ω (D) 10 Ω