The insulation performance of the overhead transmission line is a core indicator for ensuring the safe operation of power systems. There are different methods that can diagnose and measure the insulation strength of it.
1. Insulation resistance tester
An insulation resistance tester, or called a megohmmeter, measures the insulation resistance value between the cable conductor and the insulation layer. It can test the metal shielding layer as well. This indicator reflects the quality of the cable's insulation and is an important basis for determining whether the cable can continue to be used safely.
2. DC hipot tester
The DC hipot tester applies a direct current voltage that is a certain multiple higher than the rated voltage, and the insulation performance of the cable under high voltage is tested. This test can effectively detect local defects in the cable, such as bubbles and impurities.
3. Partial discharge tester
By using sensors such as ultrasonic and UHF sensors, the possible partial discharge phenomena inside the transmission lines' insulation layer can be detected. Partial discharge is an early sign of insulation deterioration, and timely detection can help prevent major failures from occurring.
4. Infrared thermal imaging detector
Use an infrared thermal imager to conduct non-contact temperature measurement on the transmission lines, observing the temperature distribution of the transmission lines during operation. Abnormally high temperatures may indicate overload, poor contact, or aging of the insulation layer of the transmission lines, and further investigation and handling are required.