in two wattmeter method of power consumption ,the two readings are 1kw and 2kw. the reactive power of the circuit is given by................?
Answers
Answer:
Two Wattmeter Method of Power Measurement
Two Wattmeter Method can be employed to measure the power in a 3 phase, three wire star or delta connected the balanced or unbalanced load. In Two wattmeter method the current coils of the wattmeter are connected with any two lines, say R and Y and the potential coil of each wattmeter is joined on the same line, the third line i.e. B as shown below in figure (A).
TWO-WATTMETER-METHOD-OF-POWER-MEASUREMENT-FIG-1
The total instantaneous power absorbed by the three loads Z1, Z2 and Z3, are equal to the sum of the powers measured by the Two wattmeters, W1 and W2.
Contents:
Measurement of Power by Two Wattmeter Method in Star Connection
Measurement of Power by Two Wattmeter Method in Delta Connection
Measurement of Power by Two Wattmeter Method in Star Connection
Considering the above figure (A) in which Two Wattmeter W1 and W2 are connected, the instantaneous current through the current coil of Wattmeter, W1 is given by the equation shown below.
two-wattmeter-method-eq1
Instantaneous potential difference across the potential coil of Wattmeter, W1 is given as
two-wattmeter-method-eq2
Instantaneous power measured by the Wattmeter, W1 is
two-wattmeter-method-eq3
The instantaneous current through the current coil of Wattmeter, W2 is given by the equation
two-wattmeter-method-eq4
Instantaneous potential difference across the potential coil of Wattmeter, W2 is given as
two-wattmeter-method-eq5
Instantaneous power measured by the Wattmeter, W2 is
two-wattmeter-method-eq6
Therefore, the Total Power Measured by the Two Wattmeters W1 and W2 will be obtained by adding the equation (1) and (2).
two-wattmeter-method-eq7Where P – the total power absorbed in the three loads at any instant.
Measurement of Power by Two Wattmeter Method in Delta Connection
Considering the delta connected circuit shown in the figure below.
TWO-WATTMETER-METHOD-OF-POWER-MESUREMENT-FIG-2The instantaneous current through the coil of the Wattmeter, W1 is given by the equation
two-wattmeter-method-eq8
Instantaneous Power measured by the Wattmeter, W1 will be
two-wattmeter-method-eq9
Therefore, the instantaneous power measured by the Wattmeter, W1 will be given as
two-wattmeter-method-eq10
The instantaneous current through the current coil of the Wattmeter, W2 is given as
two-wattmeter-method-eq11
The instantaneous potential difference across the potential coil of Wattmeter, W2 is
two-wattmeter-method-eq12
Therefore, the instantaneous power measured by Wattmeter, W2 will be
two-wattmeter-method-eq13
Hence, to obtain the total power measured by the Two Wattmeter the two equations, i.e. equation (3) and (4) has to be added.
two-wattmeter-method-eq14Where P is the total power absorbed in the three loads at any instant.
The power measured by the Two Wattmeter at any instant is the instantaneous power absorbed by the three loads connected in three phases. In fact, this power is the average power drawn by the load since the Wattmeter reads the average power because of the inertia of their moving system.
Related Terms:
Measurement of Three Phase Power: Three Wattmeter Method
Three Phase Wattmeter
Two Wattmeter Method – Balanced Load Condition
Reactive Power Measurement
Low Power Factor Wattmeter
Explanation: