Study of Partial Discharge Inception Voltage in Inverter Fed Electric Motor Insulation Systems

Abstract

This article performs a thorough evaluation of different environmental and electrical waveform characteristics affecting PDIV on electric motor winding insulation. Temperature received special attention, as it clearly affects PDIV. Additionally, the PDIV models found in the literature were reviewed. Considering that the winding of the electric motor can reach 180 ∘C during operation, the experiments were performed at high temperatures in order to evaluate the performance of PDIV models. Several models were studied regarding their accuracy at high temperatures and the advantages and disadvantages of each one were identified. Based on the analysis, a simple analytical model to estimate the PDIV of twisted pairs depending on the temperature was proposed. All in all, the proposed model was the best compromise between computational requirements and PDIV estimation accuracy at high temperatures. Finally, future lines were identified. Further studies are necessary that consider the humidity, rise time, and pulse width effect on PDIV. Moreover, new models regarding both, environmental and waveform characteristics are necessary to accurately estimate PDIV. Extended volume–time theory seems to be a good basis for that.

Static breakdown threshold modeling of quasi-uniform gas gaps with a focus on the PDIV of contacting enameled wire pairs

“…[46][47][48]), even though the above concerns have not been addressed conclusively, if at all. Moreover, there is no agreement among reported values of the secondary electron emission coefficient γ, even for the same coating material [20,21]. In fact, γ is mostly used as a 'fit factor', i.e.…”

“…• Can secondary electrons be liberated efficiently from the dielectric cathode? [17,19,20] • Is the Townsend criterion valid in the slightly non-uniform electric field occurring in configurations of the type shown in figure 1(a)? [17,[19][20][21] • Can a Townsend discharge generate a sufficient discharge current magnitude (i.e.…”

“…[17,19,20] • Is the Townsend criterion valid in the slightly non-uniform electric field occurring in configurations of the type shown in figure 1(a)? [17,[19][20][21] • Can a Townsend discharge generate a sufficient discharge current magnitude (i.e. measureable by standard PD measurement techniques) before the discharge is quenched by charge deposition on the insulating coatings?…”

Pressure scaling laws for partial discharges in wedge-shaped, dielectric-bounded gas gaps

“…The observed difference between the measured data points based on two different measurement methods will be discussed in section 5. The dotted line in figure 6 is the approximate estimate given in equation (18), while the continuous line is the exact iterative solution of equation (17). It can be seen that the approximation ( 18) is fairly accurate and, in fact, leads to accurate predictions of the PDIV as shown in figure 5.…”

“…The above equation for p • d PDIV can be solved iteratively. The first approximation is obtained by setting (α/p) ∞ /K = C 0 = 213 mm −1 bar −1 in equation (17).…”