What to do if switchgear in heavy rain areas has "water droplets"? 2 low-cost moisture-proof tips, verified by O&M staff.

2025-09-07 17:30:07

The 10kV High-voltage Switchgear of a coastal chemical plant was once affected by internal condensation, resulting in surface creepage of the busbar pillar insulator and ultimately developing into a phase to phase short circuit accident. The massive arc explosion not only destroyed the switchgear, but also caused the entire production line to shut down for three days, resulting in direct losses exceeding one million yuan. After inspection, the humidity inside the cabinet was as high as 95%, and the inner wall was covered with water droplets.

Why do switch cabinets sweat?

The principle is like taking out an ice cold soda can from the refrigerator:

When the temperature inside the cabinet is lower than the dew point temperature of the ambient air, water vapor in the air will condense into water droplets on the cold metal surface and insulation parts.

2 low-cost moisture-proof measures (tested by operation and maintenance personnel)

The following two methods have extremely low costs and can be implemented without power outages, making them particularly suitable for old station buildings with limited budgets or those that cannot be immediately renovated.

Tip 1: Install high-efficiency dehumidification bags (cost: about 20 yuan/cabinet/year)

Operation steps:

1. Material selection: Purchase high-efficiency moisture absorbing bags containing calcium chloride (CaCl ?) (usually 500g-1000g pack), and pay attention to choosing styles with water collection boxes.

2. Installation position: Open the cabinet door and hang or place the moisture absorbing bag in the bottom corner of the cabinet (outside the safe distance) to avoid blocking live parts or obstructing airflow.

3. Regular replacement: Usually 1-2 bags can meet the needs of one switchgear. Check once a month. If the water collection box is full or the moisture absorbing bag becomes hard and clumped, replace it immediately.

Advantages:

-Truly absorb moisture, not just lower the temperature

-No power supply required, absolutely safe

-Extremely low cost, only 1-2 yuan per bag

Tip 2: Paste temperature and humidity monitoring stickers (cost: about 15 yuan/piece, can be used for 2 years)

Operation steps:

1. Material selection: Purchase pointer or digital temperature and humidity monitoring stickers, with an accuracy requirement of within ± 5% RH.

2. Installation position: Paste on the inner side panel (non electrified body) or cabinet door in the middle of the switchgear for easy observation.

3. How to interpret:

-Green Zone (<65% RH): Safe

-Yellow area (65%~80% RH): Warning, need to strengthen patrols

-Red area (>80% RH): Danger, immediate dehumidification measures should be taken

Advantages:

-Visual monitoring, able to determine the internal environment without opening the cabinet

-Record peak values, some models can record the highest humidity over a period of time

-Early warning to identify risks before condensation occurs

Comparison between low-cost solutions and industrial dehumidification solutions

When must industrial dehumidifiers be used?

If you find the following situations, it means that the low-cost solution is no longer able to meet the demand and you must invest in more professional equipment:

1. The dehumidification bag needs to be replaced every week, and the monitoring sticker remains in the red area for a long time

2. Visible water droplets or insulation parts with obvious signs of moisture inside the cabinet

3. Insulation degradation or false alarm caused by moisture has occurred

Key points for selecting industrial dehumidifiers:

-Preferred semiconductor cooling type, more efficient than heating type

-Choose the type of drainage pipe that is externally led, rather than the water storage box type

-Ensure it has automatic start stop function and adjustable humidity threshold

Summary: Combination Fist for Anti Condensation

The most effective strategy is a combination of "monitoring+prevention":

Step 1 (immediate execution): Paste temperature and humidity monitoring stickers on all switchgear to fully understand the situation.

Step 2 (low-cost response): Place calcium chloride absorbent bags in cabinets with high humidity.

Step 3 (fundamental solution): For cabinets that require long-term strong dehumidification, invest in installing industrial dehumidifiers.

Finally, a reminder: Regardless of the method used, regular cleaning of the cabinet, ensuring tight sealing of cable holes, and checking whether the heater (if any) is working properly are all essential basic tasks. Sometimes, a qualified fireproof mud (sealant) can solve problems more fundamentally than expensive dehumidification equipment.