Breakdown characteristics of HFO1234ze(E)/N₂ gas mixture in non-uniform electric field under lightning impulse voltage

As a new environment friendly gas, Trans-1,3,3,3-tetrafluoroprop-1-ene (HFO1234ze(E)) has the potential to replace SF₆. In order to study the breakdown characteristics of HFO1234ze(E)/N₂ gas mixture in an extremely nonuniform electric field under the lightning impulse voltage, The lightning impulse voltage test platform was set up and an extremely nonuniform electric field with a needle-plate electrode was established. According to the test results, the effects of pressure and mixing ratio on the 50% discharge voltage U_50% of HFO1234ze(E)/N₂ gas mixture were analyzed. The results show that the U_50% of HFO1234ze(E)/N₂ gas mixture shows a “hump phenomenon” with the increase of pressure; the U_50% first decreases and then increases with the increase of the mixing ratio under positive polarity impulse voltage, however, the variation trend of 50% discharge voltage with mixing ratio under negative polarity impulse voltage is related to pressure, the variation trend of U_50% at high pressure is consistent with that under positive polarity impulse voltage, while the U_50% increases with the increase of mixing ratio at low pressure. By comparing the insulation strength of the gas mixture, it can be seen that the U_50% of 40% HFO1234ze(E)/60% N₂ gas mixture is generally higher than that of 20% SF₆/80% N₂ gas mixture.