warickwrx
Electrical
- Mar 19, 2013
- 34
I see a closed thread from an earlier date, which reads as follows:
" CDG16 (Electrical)(OP)20 Jan 05 23:31
We have two 132kV lines on the same towers for about 100km. In the past we have used a portable transformer and generator to test ZSMC on parallel lines by injecting around 140A on the one line, while the other one was first isolated and earthed, and with the next test un-earthed. Two setting groups were then prepared for the line based on the two different Z1 and Z0 measurements.
However, we have purchased the CPC100 and CU20 units from Omicron and would like to use these as they are very accurate and lightweight. But, we can only inject around 5A at 300V during this specific test. I have a feeling that the current will not be enough to see the effect of mutual coupling and that the only difference seen will be because of better earth return when the other line is earthed at both ends. This CPC100 can inject the current at different frequencies, so noise due to system frequency could be ignored.
(1) Is any body aware of such testing and how do you normally do it?
(2) Will the injected 5A be enough to detect this ZSMC? "
My question is similar as I have conducted exactly the same tests, except on a parallel 22kV distribution line of 6km in length and the wooden H pole, the structures are 8m apart with a 3 phase flat conductor and double overhead ground wire configuration. After completing the tests I obtained a Mutual coupling impedance Z0M of zero sequence of 3.681 ang 21.67°, what is this value meant to represent could it be used to show at certain values of phase currents induction will take place in the opposing lines ?
" CDG16 (Electrical)(OP)20 Jan 05 23:31
We have two 132kV lines on the same towers for about 100km. In the past we have used a portable transformer and generator to test ZSMC on parallel lines by injecting around 140A on the one line, while the other one was first isolated and earthed, and with the next test un-earthed. Two setting groups were then prepared for the line based on the two different Z1 and Z0 measurements.
However, we have purchased the CPC100 and CU20 units from Omicron and would like to use these as they are very accurate and lightweight. But, we can only inject around 5A at 300V during this specific test. I have a feeling that the current will not be enough to see the effect of mutual coupling and that the only difference seen will be because of better earth return when the other line is earthed at both ends. This CPC100 can inject the current at different frequencies, so noise due to system frequency could be ignored.
(1) Is any body aware of such testing and how do you normally do it?
(2) Will the injected 5A be enough to detect this ZSMC? "
My question is similar as I have conducted exactly the same tests, except on a parallel 22kV distribution line of 6km in length and the wooden H pole, the structures are 8m apart with a 3 phase flat conductor and double overhead ground wire configuration. After completing the tests I obtained a Mutual coupling impedance Z0M of zero sequence of 3.681 ang 21.67°, what is this value meant to represent could it be used to show at certain values of phase currents induction will take place in the opposing lines ?
