A data acquisition system is to be used to measure the value of a maximum 120-V
ID: 1814416 • Letter: A
Question
A data acquisition system is to be used to measure the value of a maximum 120-V line voltage. The maximum input voltage to the data acquisition system is 8 V and its input impedance is 1 mega ohm. The output impedance of the power line circuit is 0.5 ohms.
a) Determine the value forresistorR2 in figure if R1 has a value of 100 kilo ohms.
b) Determine the power dissipated by the two resistors.
c) Determine the loading error of the line voltage at the attenuator input
Explanation / Answer
Vin = 120 v
Vout = 8 V
form circuit ::: Vout = Vin*R2/(R1+R2)
8 =12*R2/(100 +R2)
800 + 8R2 =12R2
R2 = 200 k ohm
b)
power dissipiation = Vin^2/(R1+R2)
= 120^2/(100+200)
=0.048 w