Concept explainers
In Fig. 12.73, two wattmeters are properly connected to the unbalanced load supplied by a balanced source such that with positive phase sequence.
- (a) Determine the reading of each wattmeter.
- (b) Calculate the total apparent power absorbed by the load.
(a)
Find the readings of wattmeter
Answer to Problem 71P
The readings of wattmeter
Explanation of Solution
Given data:
Refer to the Figure 12.73 in the textbook, which shows the unbalanced load circuit with two-wattmeters.
The balanced source connected the circuit has the line to line voltage
Formula used:
Consider the positive phase sequence.
Write the expression to find the line to line voltage
Here,
Write the expression to find the line to line voltage
Write the expression to find the line to line current
Here,
Write the expression to find the line to line to current
Here,
Write the expression to find the line to line current
Here,
Write the expression to find the line current
Write the expression to find the line current
Write the expression to find the power
Here,
Write the expression to find the power
Here,
Calculation:
The magnitude of the phase voltage
Substitute
Substitute
Substitute
Substitute
Substitute
Substitute
Substitute
Substitute
Write the expression to find the voltage
Substitute
Substitute
Conclusion:
Thus, the readings of wattmeter
(b)
Find the total apparent power absorbed by the unbalanced load.
Answer to Problem 71P
The total apparent power absorbed by the unbalanced load is
Explanation of Solution
Formula used:
Write the expression to find the total real power is,
Here,
Write the expression to find the total reactive power is,
Write the expression to find the total complex power is,
Write the expression to find the magnitude of the total apparent power is,
Here,
Calculation:
Substitute
Substitute
Substitute
Substitute
Conclusion:
Thus, the total apparent power absorbed by the unbalanced load is
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Chapter 12 Solutions
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