CHOICE OF THE FORM OF THE TEST SWITCHING PULSE AND AMENDMENTS ON ATMOSPHERIC CONDITIONS FOR UHV EXTERNAL INSULATION

摘要

Experimental data of electric strength of insulation structures of UHVAC equipment (voltageabove 800 kV) are resulted at change of time to peak of positive polarity switching impulsefrom tens up to 5500 μs.It is shown, that at time to peak of aperiodical impulse τp in interval 400 μs – 800 μs externalinsulation of 1000 kV-1200 kV equipment possesses the minimal electric strength.In this range of time to peak of an impulse τp electric strength of concrete UHV insulationstructure depends a little on time to peak of an impulse.For test of external insulation of UHV electric equipment (1000 kV-1200 kV) it is offered toaccept as a standard switching impulse of aperiodical form with time to peak 500 μs and/or anunipolar oscillatory impulse with time to peak 1000 μs.Results of experimental researches on influence of atmospheric conditions on electric strengthof UHV external insulation at stress of unipolar oscillatory switching impulses of positivepolarity are also presented.Essential decrease in discharge voltage of external insulation in process of decrease ofnegative air temperature (T < 0 °C) is revealed. It is established, that correction factors onatmospheric conditions recommended by IEC Publication 60060-1 which are valid for area ofpositive air temperatures, cannot be widespread to area of negative air temperatures. Withreference to this area of atmospheric air temperatures correction factors on atmosphericconditions are offered for discussion.