Mechanical Operation Faults
These faults account for the highest proportion and are the most common issues encountered in the field.
Sticking or Failure to Operate (Opening/Closing): Components such as pivot pins, bearings, and connecting rods suffer from long-term corrosion due to rain and contamination. Combined with a lack of lubrication, this causes a sharp increase in operating resistance, leading to jamming or complete failure to move.
Incomplete Travel or Non-simultaneous Operation: Improper installation adjustments, deformed connecting rods, or shifted limit switch travel result in unsynchronized action across the three phases; for instance, one phase may close fully while another retains a gap. Forced operation can cause stress concentration and component damage.
Damage to Transmission Components: Operational impact forces can deform pivot pins, break crank arms, or bend connecting rods. Additionally, mechanical interlock failures between the main blade and the grounding blade create a direct risk of maloperation.
Electric Mechanism Failure: Issues such as motor burnout, broken control circuit wiring, or aging/damp auxiliary contacts render the electric opening/closing function completely inoperative, necessitating reliance on manual emergency operation.
Conductive Circuit Overheating Faults
These faults are often concealed and can easily lead to serious accidents.
Poor Contact at Contacts: Contact pressure between moving and stationary contacts becomes insufficient due to compression spring fatigue, annealing, rust, or breakage. Oxidation, ablation, or contamination on contact surfaces causes a sharp rise in contact resistance, leading to continuous heat generation during operation.
Loose Connections: Insufficient tightening torque on terminal pad bolts causes them to loosen under the repeated impact of load currents and short-circuit electromagnetic forces. Contact point temperatures rise rapidly; in severe cases, contacts can glow red or even melt through.
Structural Design Defects: Some early models utilized a "point contact" design, resulting in insufficient contact area and current-carrying capacity. This leads to intensified heating when carrying heavy loads or short-circuit currents, potentially causing the contacts to weld together.