Humid environments are a common challenge for electrical systems. Terminal blocks, as core components of circuit connections, directly determine system safety through their insulation performance and contact stability. If terminal blocks are exposed to humid environments for extended periods, moisture can penetrate the terminals through infiltration and condensation, leading to oxidation and corrosion of the metal contact surfaces, forming oxide layers or rust. These corrosion products increase contact resistance, causing localized overheating and, in severe cases, even terminal burn-out. Simultaneously, moisture reduces the dielectric strength of insulating materials, creating conductive paths between previously insulated components, resulting in leakage or short-circuit faults, threatening equipment operation and personnel safety. Therefore, a comprehensive protection system must be constructed from multiple dimensions, including design, installation, protection, and maintenance, to ensure the reliable operation of terminal blocks in humid environments.
During the design phase of terminal blocks, corrosion-resistant materials should be prioritized. For example, contacts can be made of chrome-plated, nickel-plated, or stainless steel. These materials have dense surfaces that effectively prevent the intrusion of moisture and corrosive substances. Insulating components should be made of weather-resistant engineering plastics, such as polycarbonate (PC) or polyamide (PA), whose stable molecular structure makes them less prone to deformation or decreased insulation performance due to moisture absorption. Furthermore, the terminal structure needs to be optimized to avoid gaps, holes, and other areas prone to water accumulation, reducing the space for moisture retention.
Proper installation is crucial for protective effectiveness. Terminal blocks should be installed in dry, well-ventilated locations, away from water sources, steam pipes, and other sources of moisture. If installation in a damp area is unavoidable, a sealed enclosure or protective cover must be used for isolation. The enclosure material should be waterproof and dustproof, and the interfaces must be sealed to prevent moisture from seeping in through gaps. During installation, ensure that terminals are neatly arranged and avoid overlapping to reduce moisture accumulation between components.
For installed terminal blocks, auxiliary protective devices can be added to enhance their moisture resistance. For example, installing an anti-condensation heater inside the terminal box can raise the internal temperature and reduce relative humidity, thereby inhibiting condensation. Alternatively, an automatic dehumidification device can be configured, such as a humidity sensor-activated exhaust fan that automatically dehumidifies when humidity exceeds a threshold, keeping the box dry. Additionally, moisture-absorbing materials, such as silica gel desiccants, can be placed around the terminals and checked and replaced regularly to continuously absorb moisture from the environment.
The quality of electrical connections directly affects the moisture-proof performance of terminal blocks. During connection, ensure a tight contact between the wires and terminals, avoiding looseness or poor connections, as poor contact can cause arcing and accelerate terminal corrosion. Simultaneously, the wire stripping length should be appropriate to avoid excessive exposed portions that increase the risk of moisture contact. After connection, exposed areas should be wrapped with insulating tape or heat-shrink tubing for double protection. Furthermore, for multi-strand wires, cold-pressed terminals or welding processes should be used to ensure a secure connection and stable conductivity.
Regular maintenance is crucial for ensuring the long-term reliable operation of terminal blocks. A detailed inspection plan is required, with regular checks of terminal appearance for rust, discoloration, or overheating. Insulation resistance testers should be used to measure the insulation resistance between terminals and between terminals and ground. If the insulation value is lower than the standard value, the cause must be investigated and addressed immediately. Simultaneously, dust and dirt on the terminal surface must be cleaned, as these substances easily absorb moisture and form conductive paths. For corroded terminals, the contact surface should be sanded to remove the oxide layer before reconnection, and conductive paste should be applied to enhance corrosion resistance.
In extremely humid environments, higher-level protective technologies can be considered. For example, terminal blocks can be potted, completely encapsulating the terminals with insulating materials such as epoxy resin to create a sealed space that completely isolates moisture; or vapor phase corrosion inhibitors can be used to form an invisible protective film on the terminal surface, inhibiting oxidation. While these technologies are more expensive, they significantly improve the moisture resistance of the terminals and are suitable for scenarios with extremely high reliability requirements.
