The amp rating on a shunt is the upper limit, exceed it too much and it becomes a fuse.
Also, the hotter the resistor gets, generally the higher the resistance goes and your measurement will become less accurate. I would guess the amp limit may be way below the fuse limit but is set to keep the resistance in spec with temperture. If you draw 4 amps, no harm in using a 100 or 500 amp shunt but the higher you go, normally the lower the resistance and the lower the voltage drop. That may cause you to lose measurement precision. But yeah, bigger than any conceivable surge current. From: Paul McCall Sent: Thursday, January 29, 2015 7:21 AM To: af@afmug.com Subject: [AFMUG] Shunt ratings Guys, Its been a few years since I looked at the shunts that we use. So, I have dumb questions on which of Forrest’s shunts to use … If a tower typically draws 3 to 4 AMPs… we should use a 5 AMP shunt? And, a tower that even sometimes draws over 5 AMPs, we should use a 10 AMP shunt? Paul McCall, Pres. PDMNet / Florida Broadband 658 Old Dixie Highway Vero Beach, FL 32962 772-564-6800 office 772-473-0352 cell www.pdmnet.com pa...@pdmnet.net
