QUESTION
An 600 mH inductor and a 3 W resistor are connected in series with a 1200-V dc power
supply.
Determine the time constant of the circuit. (5 pts)
At what time is the current equal to 1/3 of the maximum current?
Answer
Time constant :
t = 1.25μs
Time the current equal to 1/3 of maximum current;
t = 4.15x10-7 s
Explanation
t = L /R
Solve for R
P = V2 /R
3 = 12002/ R
R = 480000 ohms
Now solve for time constant
t = L /R
= 600 mH /480000
t = 1.25μs
Solve for current
I = V/R
= 1200/480000
Imax = 0.0025 A
Solve for Imax/3 :
Imax/3 = 0.0025/3
= 0.00083 A
Solve for time
t = L /(V/I)
= 600 mH /( 1200/0.00083)
t = 4.15x10-7 s
An 600 mH inductor and a 3 W resistor are connected in series with a 1200-V dc power
supply.
Determine the time constant of the circuit. (5 pts)
At what time is the current equal to 1/3 of the maximum current?
Answer
Time constant :
t = 1.25μs
Time the current equal to 1/3 of maximum current;
t = 4.15x10-7 s
Explanation
t = L /R
Solve for R
P = V2 /R
3 = 12002/ R
R = 480000 ohms
Now solve for time constant
t = L /R
= 600 mH /480000
t = 1.25μs
Solve for current
I = V/R
= 1200/480000
Imax = 0.0025 A
Solve for Imax/3 :
Imax/3 = 0.0025/3
= 0.00083 A
Solve for time
t = L /(V/I)
= 600 mH /( 1200/0.00083)
t = 4.15x10-7 s
