Terry Woods
Member
- Join Date
- Apr 2002
- Posts
- 3,170
This is for Wolfy... and anyone else that might be interested.
A couple of weeks ago, Wolfy sent a PM to me...
"Wolf here, I was wondering if you could help me with the following question....
I understand now how to find for voltage drop, but what about voltage rise.
Using the same diagram you drew the last time, with the following changes.
R=29 Ohms
L=360H
E=760V
If the switch is in position B and the inductor is fully discharged. Calculate the number of time constants after the switch is set to position A for the resistor to rise to 640V?
PS I need the to find Tau!"
I've provided the solution to this problem at the end.
But first, a bit of a recap with an earlier problem...
Let's say that the inductor is fully charged with maximum current flow occurring. Then the switch, S1, is switched from position "a" to position "b". The energy contained in the inductor now becomes the power source. However, that power begins declining immediately according to the discharge formula. Since the inductor is the source and the resistor is the load, the entire voltage from the inductor is dropped across the resistor. As the energy in the inductor declines, the current through the resistor and the voltage across the resistor also declines. The following question asks... how long does it take for the voltage across the resistor to drop from the initial value to some particular value.
A couple of weeks ago, Wolfy sent a PM to me...
"Wolf here, I was wondering if you could help me with the following question....
I understand now how to find for voltage drop, but what about voltage rise.
Using the same diagram you drew the last time, with the following changes.
R=29 Ohms
L=360H
E=760V
If the switch is in position B and the inductor is fully discharged. Calculate the number of time constants after the switch is set to position A for the resistor to rise to 640V?
PS I need the to find Tau!"
I've provided the solution to this problem at the end.
But first, a bit of a recap with an earlier problem...
Let's say that the inductor is fully charged with maximum current flow occurring. Then the switch, S1, is switched from position "a" to position "b". The energy contained in the inductor now becomes the power source. However, that power begins declining immediately according to the discharge formula. Since the inductor is the source and the resistor is the load, the entire voltage from the inductor is dropped across the resistor. As the energy in the inductor declines, the current through the resistor and the voltage across the resistor also declines. The following question asks... how long does it take for the voltage across the resistor to drop from the initial value to some particular value.
