Question Forum,
We have a motor in our plant that's run on 13.8kV (8500 hp). We recently took it down because we thought there might be electrical issues developing. We called in a tech and he claimed that because the IR readings stayed the same after one minute compared to ten minutes, that there might be condensation or other materials in the windings. In short, it failed the PI test.
My question is, can higher voltages skew the PI test? What I think might be going on is that because the IR readings were taken using a higher voltage, the insulation polarized quicker than one minute, thus making it appear that it failed the test. What if, we used a lower test voltage (5000v DC), would the insulation take longer to polarize, thus passing the PI test?
Let me know, thanks
We have a motor in our plant that's run on 13.8kV (8500 hp). We recently took it down because we thought there might be electrical issues developing. We called in a tech and he claimed that because the IR readings stayed the same after one minute compared to ten minutes, that there might be condensation or other materials in the windings. In short, it failed the PI test.
My question is, can higher voltages skew the PI test? What I think might be going on is that because the IR readings were taken using a higher voltage, the insulation polarized quicker than one minute, thus making it appear that it failed the test. What if, we used a lower test voltage (5000v DC), would the insulation take longer to polarize, thus passing the PI test?
Let me know, thanks
