Hv Disconnector Switch

Hv disconnector switches are switchgear with rated voltages ranging from 12kV to 126kV, suitable for outdoor high-voltage AC circuits. Their core function is to connect and disconnect circuits under no-load current or minimal train current conditions, creating a clear electrical disconnect point and ensuring the safety of maintenance personnel working on power-off equipment. They can also be used in conjunction with grounding switches to ground equipment, further enhancing maintenance safety. Compared to other high-voltage disconnectors, the GW4-110 offers three key advantages: First, its symmetrical dual-column structure allows for a wide contact opening angle when disconnected, ensuring a disconnect distance that meets the insulation requirements of different voltage levels. Second, the conductive parts utilize high-conductivity materials and an optimized contact structure, resulting in low long-term operating temperature rise and high reliability. Third, its overall outdoor-grade corrosion-resistant and sealed design allows for stable operation in a wide operating temperature range of -40°C to +40°C, as well as in adverse weather conditions such as strong winds, heavy rain, and icing, making it suitable for most outdoor high-voltage applications.

(I) Conductive Circuit: Low Resistance, High Efficiency, and Stable Temperature Resistance

The conductive circuit is the core of the disconnector's current transmission system and primarily consists of contacts, conductive rods, terminal blocks, and flexible connectors. The moving contacts are made of copper alloy or copper-clad aluminum (balancing conductivity and lightweight) and are silver-plated (thickness ≥ 5μm) to reduce contact resistance and operating heat. The static contacts have a built-in spring clamping mechanism to ensure tight contact after closing. This maintains stable contact even in outdoor vibration environments, preventing excessive temperature rise caused by poor contact. The conductive rods and contacts are forged in an integrated process, providing high mechanical strength and the ability to withstand electrodynamic shocks at ultra-high voltage levels.

The terminal blocks feature rectangular or circular structures, adapted to the conductor cross-sections of 110kV lines (typically supporting 240mm² to 1200mm² aluminum stranded wire/steel-core aluminum stranded wire). The terminals are tinned for enhanced oxidation resistance. A copper braided flexible connection connects the conductive rods to the terminal blocks, compensating for minor displacements during operation and preventing mechanical stress damage caused by rigid connections while ensuring electrical continuity.

(II) Insulating Supports: High-Voltage Compatible, Outdoor Durable

Insulating supports serve the dual functions of supporting the conductive circuit and providing ground insulation. They utilize specialized outdoor insulation materials and structural designs, including epoxy resin fiberglass reinforced plastic (FRP) or porcelain insulation. Porcelain supports offer enhanced pollution flashover resistance and are suitable for use in dusty and heavily polluted areas (such as industrial and mining areas). They can be sprayed with an anti-pollution flashover coating (such as RTV silicone rubber) to further enhance insulation reliability.

The height of the insulating support is designed based on the insulation distance of the voltage level. The bottom of the support is connected to the base frame with a flange, and a sealing ring is installed at the joint to achieve an IP54 protection level, preventing outdoor rain and dust from intruding into the internal metal components and preventing rust from affecting insulation performance. Some models are equipped with a grading ring at the top of the insulating support to optimize electric field distribution, reduce corona discharge, and reduce operating noise and power loss.

(III) Operating Mechanism: Flexible and Reliable, with Interlocking Safety

The operating mechanism is responsible for driving the opening and closing of the conductive circuit. It is available in manual and electric operation modes to meet different operation and maintenance requirements:

The manual operating mechanism uses a worm gear or gear transmission structure. The operator turns the handwheel (or handle) to drive the mechanism. This mechanism has high transmission efficiency and low operating torque. It also features a self-locking function in the "open/closed" position to prevent position deviation caused by misoperation or external vibration. The mechanism housing is made of cold-rolled steel with a sealed design and built-in waterproof and dustproof structure, suitable for outdoor environments.

Electric Operating Mechanism: Equipped with a dedicated motor and reduction gear, it supports remote control and precisely controls closing and opening times (closing time ≤ 10 seconds, opening time ≤ 8 seconds), meeting the operational requirements of unmanned substations. The electric operating mechanism also features built-in overload protection and travel limiters. If the mechanism becomes stuck or exceeds its travel limit, it automatically cuts off power to the motor to prevent equipment damage. An electrical interlock with the circuit breaker ensures that the disconnector can only be operated after the circuit breaker is opened, fundamentally eliminating the danger of operating the disconnector under load.

(IV) Base Frame and Earthing Switch

The base frame is constructed of welded steel sections (such as angle steel and channel steel) with a hot-dip galvanized surface for corrosion resistance, salt spray resistance, and UV aging resistance, resulting in a service life of over 30 years. Leveling bolts and fixing holes are located at the bottom of the frame to facilitate adjustment of the disconnector's horizontal angle during on-site installation, ensuring smooth operation of the operating mechanism.

Earthing Switch (Optional choice): To meet maintenance safety requirements, the high-voltage disconnector can be equipped with either an internal or external earthing switch. A mechanical interlock is installed between the grounding switch and the disconnector. The grounding switch can be closed only when the disconnector is in the open position. When the grounding switch is closed, the disconnector cannot be closed, preventing the safety hazard of "closing with grounding on." The rated short-time withstand current of the grounding switch matches that of the disconnector, ensuring it can withstand short-term grounding currents during faults.