What Are The Common Faults Of High-voltage Switchgear?

High-voltage switchgear plays a crucial role in power systems, performing switching, control, and protection functions. Its fault types are diverse. According to actual operational statistics, common faults mainly focus on the following aspects:

1. Insulation Faults (Most Common)
Moisture and Condensation: High humidity inside the cabinet causes condensation on the surface of insulating components, leading to creepage, flashover, and even short circuits. This often occurs in poor switchgear environments or when heaters fail.
Insulation Aging or Poor Material Quality: Using inferior insulating materials, such as highly hygroscopic epoxy resin, or long-term operation resulting in decreased insulation performance, causing internal/partial discharge.
Insufficient Creepage Distance and Foreign Objects: Accumulation of dirt, such as dust, salt spray, or foreign objects like small animals or screws, shortens the insulation distance, leading to discharge to ground or between phases.

High-Risk Locations: Through-wall bushings, supporting insulators, contact boxes, busbar compartments.

2. Mechanical Faults
Circuit Breaker Refusal to Operate/False Operation: Jammed operating mechanisms, burnt-out trip coils, deformed transmission components, or poor lubrication can cause the circuit breaker to fail to open when it should open, or fail to close when it should close. Handcart cannot be pushed in/cranked out: Deformed guide rails, jammed position lock plate, or interlocking mechanism not reset, causing difficulty in operating the handcart.

Interlock failure: Failure of mechanical or electrical "five-proof" interlocks, such as accidentally cranking the handcart while the circuit breaker is closed, poses a serious safety hazard.

High-risk areas: Spring operating mechanism, connecting rod, tripping half-shaft, guide rails.

3. Current-Carrying Overheating Faults

Contact Overheating: Poor contact between the moving and stationary contacts of the circuit breaker, such as loose springs, misaligned insertion, or worn silver plating, increases contact resistance, leading to severe overheating or even welding.

Busbar and Cable Connection Overheating: Loose joint bolts, insufficient copper busbar cross-section, or substandard material can cause overheating under heavy loads.

Wall Bushing and CT Overheating: Faults in the internal core or windings of the current transformer, or poor contact at the primary terminals, can lead to localized high temperatures.

High-Risk Locations: Plexicon contacts (connection between moving and stationary contacts of the circuit breaker), isolating switch contacts, busbar lap surfaces, and cable terminals.

4. Operating Mechanism and Control Circuit Faults

Energy Storage Motor Faults: Motor damage, malfunctioning limit switches, or gear jamming prevent the spring operating mechanism from storing energy properly.

Auxiliary Switch Faults: Incomplete switching or poor contact of the auxiliary switch contacts can cause signal errors or affect the secondary circuit logic.

Protection and Control Power Supply Failure: Misoperation of secondary small switches or damage to the power module can cause the switchgear to lose control power, rendering it unable to perform electric operation.

5. Environmental and Other Failures

Internal Arc Failure: An extremely serious accident, usually developing from the aforementioned insulation or current-carrying faults. An arc inside the cabinet generates high-temperature, high-pressure gas; if the pressure relief channel is improperly designed or the cabinet door is not strong enough, it may cause serious consequences such as cabinet explosion.

Interlocking Electromagnet Failure: Burnt-out electromagnets or jammed cores prevent unlocking operations.