Experimental study on PTFE ablation in high voltage circuit-breakers

Abstract

The average surface ablation of poly-tetra-fluro-ethylene (PTFE) nozzles in high voltage circuit-breakers was investigated experimentally by means of the specific ablation. Experiments were done with a test device in the current and arcing time range of 2–40 kArms and 5–17 ms, respectively. This allowed determining the dependences of the specific PTFE ablation on current and arcing time. Additionally, the specific PTFE nozzle ablation in commercial high voltage circuit-breakers was analysed in a broad range of current amplitudes and arcing times. For understanding the results more in detail, experiments with a small scale test device were performed. The different experiments yielded consistent values for the PTFE ablation. The ablation depends mainly on the total arc energy. The total ablation is given by the ablation of walls surrounding the arc and by the ablation in regions where plasma from the arc cools down. Different specific ablation values can be observed for the axial blown arc mode and the ablation controlled arc mode.

Influence of Ablation on Differential Arc Resistance

“…Figure 6 shows even more clearly, that for the lower blow pressures the ablation increases sharply above a threshold current. Qualitatively this is similar to the results of Seeger [8]. Comparing the results quantitatively is not possible though, due to the different materials and gases.…”

Perspectives on Research on High Voltage Gas Circuit Breakers

“…This needs careful design of the capacitive electric field, the flow field in the breaker and control of polymeric and contact material ablation (e.g. [11][12][13][14][15]). It has to be noted that CBs have to fulfill certain lifetime requirements, i.e.…”

Numerical and experimental investigations on thermal interaction between thermal plasma and solid polymer powders using induction thermal plasma technique

“…The first of them, PTFE, contains C and F atoms; its structural formula is [-CF 2 CF 2 -] n . It has an extremely low coefficient of friction, a nonreactive character, and high melting temperature of 618 K and evaporation temperature of 809 K. This material is widely used as a nozzle material in high-voltage circuit breakers [4,12,13,14]. Both PMMA and POM include C, H, and O atoms.…”

“…Figure 3 shows the concept and the definition of parameters in this calculation. Inside the particle, thermal conduction due to the radial gradient of the temperature were taken into account for any temperature range as indicated in equations (13) and (14). When the temperature T p (r, t) at a point inside the particle is not equal to the melting temperature T m , the temperature can be changed according to equation (13).…”

“…Inside the particle, thermal conduction due to the radial gradient of the temperature were taken into account for any temperature range as indicated in equations (13) and (14). When the temperature T p (r, t) at a point inside the particle is not equal to the melting temperature T m , the temperature can be changed according to equation (13). If the temperature T p (r, t) is the melting temperature T m , the melting phenomenon occurs to change the liquid fraction χ(r, t) as indicated in equation (14).…”