A wattmeter is an instrument for measuring the electrical power in watts for any given circuit....

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A wattmeter is an instrument for measuring the electrical power in watts for any given circuit. Figure 1 shows a small scale wattmeter in a laboratory. One day, a researcher used the wattmeter to measure the electrical power of a device that supposed to be 28W. However, the reading indicated on the wattmeter was not the same. The wattmeter is connected to a Thevenin signal source, Eth of resistance, Rth with specification given in Table 1. R1- 160 ohm |R2= 120 ohm |R3=130 ohm R4= 140 ohm Eth= 0.03 V 10 20 Figure 1. Scale 30 Table 1. Specification of the instrument 40 Number of coil turns=90 Coil resistance- 210 ohm Coil area= 10+ m² Magnetic flux density=130 Wbm-² Spring stiffness- 10-4 Nmrad-¹ (a) Solve Thevenin resistance, Rth. (b)Based on the current situation, find steady-state sensitivity, K. (c)Compute the reading indicated on the wattmeter. (d)Draw the scale with the arrow appointing at the reading obtained in 1(c). (e)Suppose that the power of the device is 28W. Find the steady-state sensitivity Kd for the desired reading. (f)Add an extra resistor, Rx into the circuit, to obtain desired steady-state sensitivity, Kd answered in 1(e). Compute the value of Rx and explain its arrangement in the circuit. (g)Based on 1(f), sketch the adjusted circuit. A wattmeter is an instrument for measuring the electrical power in watts for any given circuit. Figure 1 shows a small scale wattmeter in a laboratory. One day, a researcher used the wattmeter to measure the electrical power of a device that supposed to be 28W. However, the reading indicated on the wattmeter was not the same. The wattmeter is connected to a Thevenin signal source, Eth of resistance, Rth with specification given in Table 1. R1- 160 ohm |R2= 120 ohm |R3=130 ohm R4= 140 ohm Eth= 0.03 V 10 20 Figure 1. Scale 30 Table 1. Specification of the instrument 40 Number of coil turns=90 Coil resistance- 210 ohm Coil area= 10+ m² Magnetic flux density=130 Wbm-² Spring stiffness- 10-4 Nmrad-¹ (a) Solve Thevenin resistance, Rth. (b)Based on the current situation, find steady-state sensitivity, K. (c)Compute the reading indicated on the wattmeter. (d)Draw the scale with the arrow appointing at the reading obtained in 1(c). (e)Suppose that the power of the device is 28W. Find the steady-state sensitivity Kd for the desired reading. (f)Add an extra resistor, Rx into the circuit, to obtain desired steady-state sensitivity, Kd answered in 1(e). Compute the value of Rx and explain its arrangement in the circuit. (g)Based on 1(f), sketch the adjusted circuit.

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Option D is correct Given that 50 kVA 3300230 V 1o trans... View the full answer