What are the precautions for on-site testing of Variable Frequency AC Resonant Test System

　　The Variable Frequency AC Resonant Test System is suitable for various occasions that require AC withstand voltage.It can meet the withstand voltage requirements of high voltage and large capacity products,as well as the withstand voltage test requirements of small capacity and high voltage.It is widely used in high-voltage power detection tests. 　　Precautions before testing the Variable Frequency AC Resonant Test System

　　1)Check the appearance of the test object to understand whether the non-destructive testing items of the test equipment are qualified.If there are defects or abnormalities in the test object,the test should be carried out after elimination;

　　2)The testing site should be surrounded by railings,warning signs for ongoing testing should be hung,and a dedicated person should be assigned to monitor;

　　3)Wipe the insulation surface of the test equipment clean,and reliably ground the test equipment,the outer shell of the test object,and the non test winding.

　　For multi oil equipment,the oil should be allowed to stand still for a certain period of time according to relevant regulations before conducting the test.For example,for large capacity transformers,the oil should be allowed to stand still for 12-24 hours;For transformers ranging from 3 to 10kV,the oil should be kept stationary for 6-12 hours;

　　4)Adjust the gap between the protective balls to a discharge voltage of 105%~110%of the test voltage.Conduct two consecutive tests without significant differences,and check the reliability of the overcurrent protection device's operation;

　　5)After connecting the wires according to the test wiring diagram,professional personnel should check and confirm that there are no errors(including the distance between the lead and ground,safety distance,etc.)before preparing for pressurization;

　　6)Before pressurization,check if the regulator is in the desired position and confirm that it is in the exposed position before pressurization.The operation can only be carried out after shouting"high pressure";

　　Matters to be noted in the series resonance withstand voltage test equipment test

　　For the boosting speed,it can be slightly faster when the test voltage is below 30%.Afterwards,the boosting should be uniform,and the boosting should be carried out at about 5%of the test voltage/s,or the rated test voltage should be raised for 10-15 seconds;

　　During the boosting process,there should be no sudden increase or decrease.The changes in the voltmeter and other instruments should be monitored.When the rated test voltage is 0.5 times,the capacitance current of the tested equipment should be read.When the rated voltage is reached,the time should be calculated and the capacitance current should be re read.After the time is up,the voltage should be slowly reduced to zero before disconnecting the power supply;

　　If during the experiment,it is found that the pointer of the voltmeter swings greatly,the subject emits an abnormal sound,the indication of the milliampere meter increases sharply,and the subject emits smoke,fire,or continuous spark discharge on the insulation surface,the voltage should be immediately lowered.After hanging a ground wire on the high-voltage side,the cause should be identified;

　　For devices without clear regulations,the general withstand voltage time is 1 minute;The pressure resistance time of tools such as the insulated green rod is 5 minutes.After the experiment is completed,the ground wire should be hung in a timely manner,and then the relevant parts should be contacted without any heating phenomenon;

　　Precautions after the experiment

　　The insulation resistance and absorption ratio of the tested equipment should be measured before and after the experiment,and there should be no significant difference between the two measurement results.