Indoor High-Voltage AC Earthing Switch

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 1. Product Overview

The indoor high-voltage AC earthing switch is an essential safety auxiliary equipment dedicated to 40.5 kV indoor power distribution systems. It is mainly installed inside high-voltage switch cabinets to provide reliable grounding protection for high-voltage equipment during power-off maintenance, and delivers safety isolation against system faults.

Compliant with GB 1985-2004 and IEC 129 international standards, the product adopts optimized structural design with integral metal frame, silicone rubber composite insulators and stable mechanical operating assembly. It features compact layout, reliable contact performance, precise interlock function and convenient maintenance, widely matching indoor high-voltage switchgear for industrial, civil and power station power distribution occasions.

2. Core Working Principle

Before maintenance of high-voltage equipment, the circuit must be fully de-energized and verified voltage-free. Operate the earthing switch to close the three-phase moving contacts onto the fixed grounding terminals, so that the live parts of the equipment are reliably connected to the earth grid. This structure can release residual induced electricity on power equipment, avoid accidental electric shock hazards caused by sudden power transmission, and limit overvoltage during system failures to protect operators and electrical devices. After maintenance work finishes, the switch shall be opened to separate the grounding circuit completely before power recovery.

3. Main Technical & Structural Features

1). Safe and reliable insulation Equipped with high-performance silicone rubber insulators, adapting to ambient temperature range of -25℃ ~ +40℃, pollution class II, seismic resistance up to grade 8, applicable to working altitudes below 1000 m. Excellent anti-aging and anti-fouling performance, stable insulation capacity under high humidity.

2). Stable contact & grounding performance Three-phase independent contact structure with thickened conductive contact parts, tight fitting during closing to ensure low grounding resistance. Standard flexible copper connections (240 mm in length; customized lengthening available) guarantee unobstructed conductive loops.

. Anti-misoperation interlock design Built-in mechanical interlock device, which locks the switch in closed state automatically after grounding, effectively preventing mistaken opening during maintenance; interlocked with the main circuit breaker to prohibit grounding operation under live conditions. Equipped with visual open/close indicator for clear status identification.

4). Flexible and durable operating mechanism Horizontal linkage transmission structure with smooth rotation without jamming. Manual rotary operation mode: clockwise for closing, counterclockwise for opening. Rotating parts are pre-lubricated for long-term flexible operation, resistant to rust and mechanical wear.

5). Easy installation & low maintenance Integrated mounting base, directly fixed inside standard 40.5 kV switch cabinets. Simple daily inspection and cleaning procedures; only regular lubrication for rotating joints required, no complex disassembly.

4. Applicable Operating Environment

Ambient temperature: -25°C ~ +40°C

Altitude: ≤1000 m

Humidity: Daily average relative humidity ≤95%, monthly average ≤90%

Site conditions: No fire/explosion risks, severe dust, corrosive gas or violent vibration; pollution grade II, seismic intensity ≤ Grade 8

5. Main Application Scenarios

1). Power grid substation indoor high-voltage cabinet power-off maintenance grounding

2). Supporting matching for 40.5 kV indoor complete high-voltage switchgear

3). High-voltage power distribution rooms of factories, mines, commercial complexes and civil buildings

4). Special industrial high-voltage power distribution systems requiring safety isolation protection

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