This is an automated archive.
The original was posted on /r/electricians by /u/InvestigatorNo730 on 2024-01-12 06:10:43+00:00.
So I have a bit of a theory question for yall.
So we did some ATS testing the other day a simple IR scan and cleaning, an contact resistance testing via checking voltage drop and circuit amperage.
My question is if the resistance stays constant shouldn't you voltage change based off change of amperage? We had a situation where one of the ATS we tested had a voltage drop across the contactsof roughly 0.011Vac at a current of 22A for phase A and B how ever phase C had a voltage drop of 0.011Vac at 40A.
Following ohms law A and B are 500micro ohms
While C is 275 micro ohms. By NETA standards A and B fail contact resistance, yet our neta4 tech and EE said just to note it down since we couldn't doctor the connection and nothing popped up on thermal. I know via multimeters and clamps were getting an RMS reading not a peak reading, but if contact resistance is similar I should see a difference in voltage right?