Indoor Load Switch Common Faults | Causes, Diagnosis & Preventive Maintenance Guide

Common operational faults of indoor load switches primarily concentrate on three core aspects: mechanical operation, electrical performance, insulation, and arc extinguishing. These issues can be broadly categorized as follows and are often related to component aging, environmental influences, or improper operation.

1.Mechanical Faults The most typical issue is abnormal operation during opening and closing. This includes excessive resistance, jamming, or even refusal to operate when manually turning the handle. For motor-operated switches, common problems include no response after receiving a command or incorrect position indication after operation (e.g., "false open" or "false closed"). These faults are usually caused by wear or rust in the transmission linkage, fatigue in the spring mechanism (reduced elasticity or breakage), installation misalignment, or solidification of lubricating grease. Another issue is poor contact at the contacts, manifested as abnormal heating of the switch body during operation, unusual discharge sounds, or excessive contact voltage drop. This is typically due to long-term contact wear and oxidation, loosening of the contact pressure springs, or excessive operation exceeding the mechanical lifespan.

2. Electrical and Safety-Related Faults First, insulation degradation or failure can occur, leading to nuisance tripping of leakage protection devices, a significant drop in insulation resistance, or, in severe cases, breakdown and carbonization of insulating components (e.g., epoxy resin parts, insulating pull rods). These problems are often caused by high humidity, natural aging of insulating materials, or the accumulation of contaminants like dust and oil inside the switch, forming conductive paths. Second, failure of the arc-extinguishing function may happen, characterized by intense arcing, a pungent ozone smell during load interruption, and, in extreme cases, contact welding or switch body burnout. The main causes include aging and leakage in the arc-extinguishing device (e.g., compressed-air or vacuum interrupters), decreased vacuum levels, or interruption currents exceeding the switch's rated capacity.

3. Indirect Faults Caused by Environmental and Operational Factors Additionally, faults can be indirectly triggered by adverse environmental conditions or improper operation. For example, high temperatures accelerate component aging, while low temperatures can cause mechanical transmission systems to jam. Frequent interruption of fault currents or failure to follow proper operating procedures further exacerbates wear and damage to mechanical and electrical components.