This article describes the norms and measures to be followed when using Hipot tsters using the instrument. When using this instrument, special care must be taken to ensure safety.
Warning: This hipot tester has a test high voltage output of 10KVA. If you operate the instrument incorrectly or wrongly, it will cause accidents or even death! Therefore, for your own safety, please read the precautions in this article carefully and keep in mind to avoid accidents.
Wearing Insulation Gloves
Wear insulated gloves when using the instrument to protect yourself from high voltage, but try not to touch live conductors with your hands during high voltage testing.
There is a safety ground terminal on the rear panel of the tester. Please use a suitable tool to connect this ground to the electrical ground (safety ground, earth ground). If there is no good grounding, when the circuit of the power supply is short-circuited to the ground or the connection wire of any equipment is short-circuited to the ground, there may be high voltage in the chassis of the test instrument, which is very dangerous, as long as anyone touches the instrument chassis in the above state, an electric shock may occur. So make sure the safety ground terminal is connected to the ground.
Test lead connection
First press the [STOP] key, make sure that the DANGER indicator is off, and then connect the test leads. When connecting the DUT with a test lead, please connect the DUT with the test lead at the RTN / LOW end first. If the test leads on the RTN / LOW end are not completely connected or dropped, it is very dangerous, because the entire DUT may be filled with high voltage. After inserting the high-voltage plug of the high-voltage test line into the HV, it must be turned 90 degrees clockwise to lock it to prevent the test line from falling off.
Before the test, you must check whether the test leads on the HV or RTN / LOW end are connected properly, no loose or detached.
Abort (Suspend) the test
To change the test conditions, first press the STOP switch once to make the 10 kVA hipot tester exit the test preparation state and make sure that the DANGE Rlight is off. If you need to take a break or leave the test place, please turn off the power switch to prevent safety hazard by accidentally touching the start switch.
Special care should be taken when using the instrument in remote control mode operation, because the start and stop of the high voltage is controlled remotely, and the operator cannot know the actual working status of the hipot tester through the interface. Pay special attention to the reliable remote control connection:
- The “STOP” button, it must be connected reliably. Press the “STOP” button before replacing the DUT.
- When working in a crowded work environment, the remote control switch must have an “INTLOCK” interlock switch and a high-voltage indicator. Disconnect the “INTLOCK” interlock switch before replacing the DUT.
- When testing the voltage output, do not allow the operator or other personnel to touch the DUT, test leads, probes, output terminals and the surrounding area.
Test completion confirmation
If you have to touch the high-voltage area such as the DUT, test lead, probe, or output terminal due to reconnection or other test-related conditions, please confirm:
- The power switch has been turned off or the working status displayed by the instrument is not a test status, and the DANGER light is off.
- The DUT may be filled with a high voltage on it after the test. Pay special attention to whether the DUT is completely discharged.
High voltage test discharge
In a high-voltage test, the test leads, test probes, and DUT are charged with high voltage. The hipot tester has a discharge circuit, and sometimes it still needs to be discharged after the output is cut off. There is still a danger of electric shock during discharge. Do not touch any place that may cause electric shock. At the end of the test, the discharge circuit of the instrument begins to force discharge. Do not remove the DUT during the test and before the discharge is completed.
The time for which the voltage is completely discharged is determined by the test voltage used and the characteristics of the DUT itself. During the test, the discharge of the DUT is achieved through the secondary side of the transformer (about 2K resistor). The discharge of 6000V voltage from 10uF capacitor to 30V takes about 0.1S. The instrument’s fixed discharge time of 0.2S can ensure that the discharge is complete. The internal filter capacitor of the instrument is discharged through the discharge circuit, which can ensure that the discharge is complete within 0.2S.
Assuming that high voltage is applied to the DUT is equivalent to high voltage applied to a 0.01uF capacitor in parallel with a 100MΩ resistor circuit, if the DUT is separated during the test or before the discharge is completed, the DUT is discharged to a voltage of 30V, it takes about 5S for a test voltage of 5000V and 3.5S for a 1000V.
Calculation formula of discharge time: t = -ln (30 / U) × R × C
t: discharge time
30: Residual discharge safety voltage 30V
U: Test set voltage
R: discharge impedance of the DUT, about 2KΩ resistance
C: capacitance of the DUT
If the time constant of the DUT is known, the time required for discharging to 30V can be obtained by the above formula after the output is cut off.
Turn the power switch on or off
Once the power switch is cut off, if you want to turn it on again, you need to wait for a few seconds. Do not turn the power switch on and off continuously to avoid erroneous actions. It is very dangerous to continuously switch on and off especially when there is high voltage output.
When turning the power on or off, do not connect anything to the high-voltage output to avoid danger caused by abnormal high-voltage output.
In the test state, do not touch the high voltage area
When the10kVA hipot tester is in the test state, the high-voltage output end, high-voltage test lead, high-voltage probe, DUT, and their exposed conductors all contain dangerous high-voltage electricity. Do not approach or touch these areas.
Warning: Do not touch the alligator clips on the test line. When thehipot tester is in the test state, the rubber skin on the alligator clip is not enough insulation. Touching it is very dangerous!