Analysis Of The Causes And Operating Status Of High-voltage Disconnecting Switches Failing To Close Or Open.

During the operation and maintenance of substations, the operating status of High Voltage Disconnect Switch directly affects the electrical isolation effect between equipment. Field operation records show that some equipment exhibits insufficient closing/opening travel and incomplete contact positioning after operation. These anomalies are often related to the mechanism's condition, transmission structure, and contact conditions, requiring technical analysis in conjunction with the equipment structure. If the contacts are not fully closed, the contact resistance may increase significantly, further causing localized temperature rise or arcing.

Mechanical Transmission Structure-Related Incomplete Actions

In years of field maintenance experience, problems with the mechanism and transmission system are among the common causes of incomplete closing/opening of high-voltage disconnectors. The operation of the disconnector relies on the linkage of components such as connecting rods, crank arms, and pins. If any part of these components is worn or corroded, the mechanism's travel may deviate.

In long-term operating environments, if the mechanism box becomes damp or infiltrates with water, bearings and rotating parts are prone to corrosion, leading to increased operating resistance and insufficient switch movement. After years of operation, some equipment may experience issues such as loosening of connecting rods or decreased strength of connecting components, preventing the transmission stroke from reaching the designed position, resulting in incomplete opening or closing.

Insufficient closing stroke caused by abnormal contact

The condition of the contact structure also affects the operating position of the high-voltage disconnector. When the insertion depth of the moving contact is lower than the design value, the contact pressure decreases, the contact surface resistance increases, and localized heating is likely to occur.

Common situations include:

• Aging or deformation of the contact finger spring: Reduced elasticity leads to insufficient clamping force and loose contact between the moving and stationary contacts.

• Oxidation or wear of the contact surface coating: Damage to the conductive surface increases contact resistance.

• Structural assembly deviation: Positioning errors during installation or maintenance result in insufficient contact insertion depth.

Under the influence of operating current, these contact problems will gradually amplify, the contact surface temperature will continue to rise, and in severe cases, it may induce arcing or insulation degradation.