- #1
kenneth edmiston
- 45
- 2
- TL;DR Summary
- Coworker measured the output voltage of a zero sequence CT for a ground fault relay. This seems wrong.
I don’t know the ratio of the CT. I’m just looking for an explanation on this. I thought in order to measure output voltage you need to pass the current through a resistor and read the voltage drop.
A co worker put 400a through the CT and measured 130v. Something just seems off to me. Can you just hook up your DMM and test the output voltage? The intent was just to see if the CT was operating, not for a quantitative measurement.
But this seems dangerous. A modern voltmeter has an input impedance of around a megohm or maybe 10. Seems like the CT output voltage could get away from you quickly.
Any insight will help. Thanks!
A co worker put 400a through the CT and measured 130v. Something just seems off to me. Can you just hook up your DMM and test the output voltage? The intent was just to see if the CT was operating, not for a quantitative measurement.
But this seems dangerous. A modern voltmeter has an input impedance of around a megohm or maybe 10. Seems like the CT output voltage could get away from you quickly.
Any insight will help. Thanks!