help me solving this circuit for unknown values

Status
Not open for further replies.
R

rudr_p

Member level 1
Member level 1
Joined
Sep 17, 2010
Messages
35
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Activity points
1,507
The resistance X and Y has to be found out and the only given values are Vd,V and Resistance R.
Untitled.png

I tried but somehow, I cannot figure it out.
and suppose if we have the voltage V when the value of resistance of known resistance R is infinite/open circuit that means the cicuit only contains X and Y. is it possible to find the resistance out, I mean by combining the upper two conditions

The only given values are the value of R,Vd and V.
Its an DC earth leakage detector circuit
Click to expand...



Thank you
 
Last edited:

rudr_p said:
The resistance X and Y has to be found out and the only given values are Vd,V and Resistance R.
Click to expand...
There is no unique solution.
For example, if V = Vd/2, then the voltage across Y is the same as the voltage across R and X. So in that case resistance Y must be equal to the parallel combination of R and X.

rudr_p said:
...and suppose if we have the voltage V when the value of resistance of known resistance R is zero...
Click to expand...
If resistance R is zero then voltage V must be zero.
 

@godfreyl I don't understand your explaination.
If the resistance R is zero then the voltage cannot be zero but there will be some voltage between those point showing the drop in X.
 

You can find the ratio X/Y, but without mmore information there is no way to find actual values.

Let K = 1/(1/R + 1/X) so K is the resistance of X in parallel with R, then the circuit is simply a potential divider V/Vd= K / K+Y, I will leave the algebra to get the actual ratio as an excersise.

And if R is zero then V is zero and all the voltage is dropped across Y, you cannot develop a voltage across zero ohms and R is in parrallel with X.

Regards, Dan.
 

Either you didn't manage to phrase the problem clearly or it has no solution.
 

Omg!!! sorry!!! godfreyl and Dan Mills , I actually wanted to say that resistance R is open as in suppose there is no R in the circuit when measuring the voltage V....
 

Status
Not open for further replies.

Similar threads