I need to work out the required value of a parallel shunt resistor to shunt a meter.
I have been given the maximum incoming current of 200A (I), the resistance of the meter (Rm) which is 0.1 Ohm and been told that the maximum the meter can read is 1mA (Im).
I've gone down this route:
Voltage = I x Rm = 200 x 0.1 = 20V
Then worked out the current that the meter is pulling = 20V/Rm = 200A
Correct me if i'm wrong, but doesn't that mean that the shunt resistor (Rs) is effectively 0? So the shunt current (Is) be 20/0 = 20A?
Any pointers would be appreciated.
Thanks for your reply.
Ok, I take it you mean the wording in the question.
"Determine the required value of the shunt resistance if the maximum value of the current I is 200A. The meter can read a maximum of 1mA and has a resistance of 0.1Ohm."
There is a diagram which basically consist's of a meter and a shunt resistor in parallel.
So, 0.001 x 0.1 = 0.1mV
Therefore, Rtotal = 0.1mV/200A = 0.0000005 Ohm
Rmeter - Rtotal = 0.999995 Ohm?
Yes, I purposely didn't include notation.
Are there any programs you recommend that would enable me to write equations on the computer and copy them into the forum etc?
Sorry about my lack of knowledge, I'm a complete noob to all of this.