Improved Breakdown Strength of Polypropylene Film by Polycyclic Compounds Addition for Power Capacitors

Abstract

In this paper, an improved method for the electric performance of polypropylene (PP) film was proposed to promote the safety and stability of power capacitors. Modified PP films containing three different polycyclic compounds were prepared, which showed good thermal properties and decreased DC conductivity. The DC breakdown strength of the modified PP films under both positive and negative voltage is increased compared with that of the original film. The deep traps introduced by polycyclic compounds and the decreased carrier mobility give an explanation of the decreased DC conductivity. A quantum chemistry calculation was further performed to clarify the mechanism for improving electrical performance, presenting that polycyclic compounds with a high electron affinity and low ionization energy can capture high-energy electrons, protecting the PP molecular chain from attack, and then increase the breakdown strength. It is concluded that the modified PP films by polycyclic compounds have great potential in improving the insulating properties of power capacitors.

Dielectric Surface Flashover under Long-Term Repetitive Microsecond Pulses in Compressed Gas Environment

“…1/2 (7) Since the initial charge carriers in the gas/solid flashovers are related to the partial discharge at the triple junction, and the main source of the surface charge is from the gas part, according to Equation ( 7), it can be illustrated that pt delay is also the function of E/p during the flashover process [32]. In order to compare the surface insulation strength at different pressure ranges, the relationship between E/p and pt delay was plotted at different PRFs, in air and SF 6 , respectively, as shown in Figure 19.…”

“…Conventionally, for a dielectric/gas composite insulation system between a couple of parallel-plane electrodes, insulation failures are mostly caused by surface flashover instead of bulk breakdown, since the interface is always the weakest part under RMPs. In previous investigations, factors affecting surface flashover, mainly in gas-insulated switchgears (GISs), were systematically studied [ 3 , 4 , 5 ] and various methods have been developed to improve bulk and surface insulation strengths under AC and DC conditions [ 6 , 7 , 8 ]. When it comes to pulsed flashovers, the physical processes and mechanisms of solid-vacuum surface flashovers have been discussed in detail in pulsed power systems [ 9 , 10 ].…”

“…Materials 2021, 14, x FOR PEER REVIEW 2 of 23 insulated switchgears (GISs), were systematically studied [3][4][5] and various methods have been developed to improve bulk and surface insulation strengths under AC and DC conditions [6][7][8]. When it comes to pulsed flashovers, the physical processes and mechanisms of solid-vacuum surface flashovers have been discussed in detail in pulsed power systems [9,10].…”

Crystallisation regulation of long‐chain branched polypropylene on dielectric performance and energy density for metallised film capacitors

“…However, PP films can only operate stably for a long time below 85°C [6]. In a high-temperature environment, the decrease of the breakdown strength and the increase of the conductivity loss of the PP film can easily accelerate the decay of the capacitance and service life, resulting in frequent failures of MFCs [7,8].…”

Breakdown strength improvement of polypropylene by introducing long-chain branched structures for film capacitors

“…However, the stable operating temperature of PP is only 85 • C [3][4][5]. The breakdown strength of PP drops sharply in a high-temperature environment, which is likely to cause failures such as bulging and explosion of the capacitors [6,7]. With the development of electronic equipment in the direction of larger capacity, higher in leakage current and a decrease in breakdown strength [12].…”