The reason for the moisture failure of the lightning arrester is the inspection of the DC surge protector

May 23, 2022

Moisture inside the signal arrester is a relatively common fault phenomenon. The specific performance is that the insulation resistance is lower than 2500MΩ, and the power frequency discharge voltage drops.

1) The loosening of the fastening nut on the top of the lightning arrester leads to water leakage; the gasket of the sealing bolt on the top of the porcelain sleeve is not welded, and the gasket will age after long-term use, and it is not surprising that moisture and moisture penetrate into the cavity along the screw seam ;

2) The small hole of the bottom sealing test is not welded or blocked, causing moisture or water vapor to enter;

3) Many factors such as the rupture of the porcelain sleeve, the presence of sand holes, the cracks in the gluing of the skirt, etc. will lead to the entry of moisture and moisture;

4) The rubber gasket is aged and cracked after long-term use, and loses its sealing effect;

5) There is a gap in the fan-shaped iron sheet used for pressing at the bottom, and it is not plugged tightly. The position of the bottom sealing rubber gasket is not correct, causing moisture to penetrate into the gap;

6) The joint between the porcelain sleeve and the flange is not smooth or the porcelain sleeve has cracks.

What aspects should be checked for the installed DC surge protector

1. Appearance quality

The appearance surface of the DC surge protector should be smooth and scratch-free, and there should be no deformation, and the surface color should be uniform without obvious changes in depth; the logo on the DC surge protector should be complete and clearly visible, and the nameplate should be stable. There is no sign of movement.

2. Warning function

The DC surge protector has a certain warning function. In the case of normal or faulty conditions, different signs or indicators of different colors will appear, making it clear at a glance.

3. Protective grounding

When the DC surge protector is properly installed and connected, all metal parts of the surge protector that are not live and accessible on the DC surge protector should form a whole and be effectively connected to the protective earth terminal.

4. Installation process

Check the product model of the surge protector, and the products tested by the nationally recognized testing laboratory should be used; check the technical parameters of the surge protector to see if they meet the requirements of lightning protection testing specifications. The parameters generally include technical parameters such as the maximum continuous working voltage UC, nominal discharge current, maximum discharge current, and voltage protection level; check whether the installation position of the surge protector is consistent with the design requirements, whether the wiring method is correct, and whether the connecting line is straight. Whether the diameter and length of the grounding wire meet the requirements, and whether the grounding wire is firmly connected.

5. Flame retardant properties

Use non-contact to quickly measure the surface temperature of the surge protector in the low-voltage power distribution system, check the requirements for flame retardant in the manual, etc.
Uchi is a leading manufacturer and solution provider of lightning arresters and surge protectors, providing lightning protection equipment such as DC and AC power surge protectors - computer room network monitoring signal and video two-in-one arresters to the world.