1. Two wattmeters are used to measure the power in a 3-phase balanced system. What is the power factor of the load when one wattmeter reads twice the other?
2. 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 wattmeters reads half of the other (both positive), then the power factor of the load is
3. A wattmeter is connected as shown in the figure. The wattmeter reads
- Zero always
- Total power consumed by Z1 and Z2
- Power consumed by Z1
- Power consumed by Z2
5. In a two-wattmeter method of measuring power in a balance 3-phase circuit, the ratio of the two wattmeter reading is 1 : 2. The circuit power factor is
6. 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
- 0.2 & 6 kVAR
- 0.2 & 6 √3 kVAR
- 0.32 & 2 kVAR
- 0.32 & 2 √3 kVAR
7. In a balanced 3-phase 200 V circuit, the line current is 115.5 A. When the power is measured by two wattmeter method, one of the wattmeter reads 20 kW and the other one reads zero. What is the power factor of the load?
8. The minimum number of wattmeter(s) required to measure 3-phase, 3-wire balanced or unbalanced power is
9. In a three-phase supply driving a load, what is the minimum number of single-phase watt meters required to measure the power and power factor?
10. In two wattmeter method of measuring 3 phase power, the power factor is 0.5, then one of the wattmeters will read
- 0.577 W
- 1.414 W