Set up: Using the Multisim software, implement the following circuit
Rx WM
R1
15kΩ
R2 2000Ω
25Ω
Idc: 25.0uA
The ammeter denoted by the green circled Ietfer (A) will play the role of the PMMC with an FSD current of Im=50A. The coil resistance is R=50Ω and the multiplier resistor R=15KΩ. The shunt resistor R is a variable one with a maximum resistance of 200Ω. Its value can be adjusted to correct for any drop in the source voltage, which will affect the correctness of the measurement.
Questions:
1. Set the variable resistor to R=50Ω (25% of its full resistance). Calculate the values of R at FSD, 0.75FSD, 0.5FSD, and 0.25FSD. Theoretically, Coil Current I Resistance R, 0.25FSD 0.5FSD 0.75FSD FSD
2. After implementing the circuit on Multisim, vary the value of R, as listed in the table below, and measure the PMMC current corresponding to each value. Given that the FSD current is Im = 50A, state the FSD percentage corresponding to each measured value.
R, PMMC Current % of FSD
0Ω
5KΩ
10KΩ
15KΩ
UNOS
45KΩ
100MΩ
4. Theoretically, calculate the required adjustment in R if the source voltage drops to 1.2V. Use R=15KΩ in your calculations.