shunt rigging [RE-wrenches]

[R. Sparks Scott]

> he needs up to 1000 amp readouts.
>It lists a standard 50/500 shunt on the meter. If he puts 2 of them in
>series and takes the voltage drop readings from the ends can he just double
>the dial readings?

	Bob;

	For this to work, the shunts will have to be in *parallel*, not series.
Think about it, what he needs is a 50 mv/1000 A shunt. Running 1000 amps
through just one 50/500 shunt will produce 100 mv, overloading the meter.
Two shunts in series will prduce 200 mv, really pinning the meter. Two
shunts in parallel will drop a total of 50 mv at 1000 amps, and then the
full scale reading on the meter would need to be doubled for a correct
reading.
	Another way of doing this if he wants to try it with only one 50/500 shunt
(and make the current measurement quick) is to insert a potentiometer in
series with the meter and calibrate the reading while drawing a known
amount of current. It might not be as exactly accurate as two shunts, but
it will be very close. Of course, there will be a very small calibration
error due to changes in temperature of the resistor, but when you're in the
1K amp range, a few milliamps one way or the other aren't going to matter
much on the reading.
	Good luck.

	-S

- - - - - - -
To send a message:
 RE-wrenches at topica.com

The archive of previous messages: 
 http://www.topica.com/lists/RE-wrenches/

To unsubscribe send a message to: 
 RE-wrenches-unsubscribe at topica.com

To check out the other RE-Wrench participants:
 www.mrsharkey.com/wrenches/index.html

Hosted by Home Power magazine: 
 www.homepower.com

For info contact list moderator by email:
 michael.welch at homepower.com

___________________________________________________________
T O P I C A  http://www.topica.com/t/17
Newsletters, Tips and Discussions on Your Favorite Topics