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Triple Frequency Induction Withstand Voltage Tester is a device that confirms no current flows through the circuit by applying an external voltage. Therefore, when there is no current phenomenon due to disconnection of the connecting cable, poor contact, etc., it may be mistakenly considered as PASS, which means that the voltage on the tested object may be unrelated to the rated voltage. On the surface, a withstand voltage test has been performed, but in reality, the measured voltage is too low. Even if it is a defective product, the withstand voltage tester may incorrectly judge it as non-defective and display PASS. As a result, defective products flow into the market as qualified products. However, since the withstand voltage test is a safety standard test, if it is not done correctly and accurately, it can cause various fatal failures and disputes in the market.
Checking the equipment before starting work can reduce misjudgments in withstand voltage tests caused by test equipment issues. However, with the increasing automation of testing equipment, it must be noted that even if a daily inspection is performed at the beginning of work and work starts without any problems, poor contact caused by a malfunction of an automatic mechanical device may go unnoticed until the next inspection. In the worst case, defective products may be mixed into the entire day's production.
How can we avoid the above situations with the Triple Frequency Induction Withstand Voltage Tester? Here, we introduce several practical operation methods and the advantages and disadvantages of each method.
1. Method using a relay
First, close the relay to perform the withstand voltage test. Since the relay is closed, a short-circuit current flows, and the withstand voltage test results in FAIL. Displaying FAIL indicates that there is no disconnection or poor contact, and current is flowing. Then open the relay (OFF) and test again. Since the initial test was FAIL, confirming that the test equipment is normal, it can be concluded that the withstand voltage test has been achieved.
This method is effective, but it requires two withstand voltage tests per tested object, increasing contact time.
2. Method of setting the current passing through a qualified product as the lower limit of the withstand voltage test current
Set the current passing through a qualified product as the lower limit of the withstand voltage test current. When the current detected by the withstand voltage tester is lower than this value, it can be confirmed that there are phenomena such as disconnection or poor contact.
Basically, withstand voltage testers can set the lower limit current, so this method is very effective when a certain amount of current passes through a qualified product. However, if the current passing through a qualified product is very small or basically does not pass, it cannot be distinguished from leakage current from cables, etc., and thus it may not be possible to detect abnormalities such as disconnection or poor contact.
3. Method of confirming the short-circuit current flowing through each port and then performing the withstand voltage test
Operate SW1 and SW3, or SW2 and SW3, to form a loop including the test port. After confirming that a short-circuit current flows, perform the withstand voltage test. If no short-circuit current flows, then the wiring of that port is abnormal.
Since the wiring is checked before the withstand voltage test, even if it takes only a little time, it still increases contact time, which is a drawback of this method.
4. Monitoring the voltage at the voltage application part
The voltage displayed by the Triple Frequency Induction Withstand Voltage Tester is the voltage at the generating end, not the voltage at the voltage application part of the tested object. Therefore, if the wiring is normal, the voltage at the generating end and the voltage at the voltage application part should be the same. If there is a disconnection or poor contact, the voltage at the voltage application part will be less than the voltage at the generating end, and it can be determined that the wiring is abnormal. Since it can detect wiring abnormalities during the withstand voltage test and has little impact on the contact time of the production line, this is convenient. However, unlike other methods, a small current flows through the voltmeter connected in parallel to the measured object, so this method cannot be used when measuring insulation resistance before and after the withstand voltage test.
Note: The above information and technical parameters are compiled and released by Yangzhou Darni Electric Co., Ltd.
