Transformer partial discharge in power
Substation a multiterminal substation a so-called multiterminal measurement is mainly used to determine partial discharge area is a coil to ground or inside the coil. Because in the case of the two kinds of wiring, UU14 two phase support a phase connection remains the same. Have more reduce the induction ratio Et the latter than the former, such as partial discharge before and after data are basically identical, therefore, the location of partial discharge was more likely to end, such as partial discharge data before and after the change is bigger, the partial discharge location inside the coil (especially between interturn, bread, interlayer).
Compared to (a) and (b) two cases, though, in the two phase support a phase induction voltage ratio significantly decreased, but the potential sites of the U1 phase winding or remain the same, or have a certain rise.
So generalisations "support or not there is no change of partial discharge, the presence of partial discharge in terminal" is a bit inappropriate. Just the usual transformer in addition to the end, the insulation structure, insulating distance have a certain margin, therefore, more likely to end there is a problem.
Winding relations with potential under two kinds of connection mode it is worth noting that using two phase is supported a phase without using a phase of the reason: U1 phase, for example, when the single phase excitation, V1, W1 short answer or not, because of the magnetic circuit length is differ, V1, W1 phase voltage is not consistent, so have UV1 > UW1, such as using a phase support can cause voltage of the U1 voltage, higher or lower than the original comparative test is not strong. And using two phase support, V1, sub W1, forced UV1 = UW1, so the magnetic flux in two magnetic circuit to get the average allocation, namely uu1 UV1 = UW1 = 015. So as to make the test voltage can be calculated to ensure that the before and after the comparative.
A phase support two-phase V1 is a transformer partial discharge test, the measured V1 that partial discharge quantity is 2000 PCS, at the same time measured W1 phase partial discharge quantity is 3000 PCS, the UV1 = 015 um, U1/11732, UW1 = 0125 um, U1/11732, UV12W1 = 0175 um, U1/11732. After analyzing suspects partial discharge power exists in V1, W1 phase, therefore, to take such as connection mode, makes UV12W1 = 0, UV1 = UW1 = 018 um, U1/11732, measured V1, W1 phase discharge are less than 100 PCS. Test confirmed that the partial discharge power and the V1, W1 end support electricity 6 a phase two connect status has nothing to do, and with V1, the potential difference between W1. Check V1, W1 alternate with, found that W1 phase adhesion with metal particles on the folding screen, clean up after, fault disappear.