HF-WC-633 Disconnector Contact Pressure Tester

High-voltage switchgear is widely adopted in power systems. Outdoor disconnectors are exposed to atmospheric environments and vulnerable to climatic conditions, leading to harsh operating conditions and frequent mechanical or electrical faults. The contact surfaces are easily eroded by rainwater, dust and harmful gases, resulting in poor contact and overheating. The contact pressure springs may undergo thermal annealing, reducing contact pressure and triggering a vicious cycle of overheating, which can eventually burn out contacts and cause accidents.

During maintenance, technicians usually only replace obviously failed or broken springs. However, degraded springs without visible damage cannot be identified. During subsequent operation, uneven current distribution among contacts arises due to inconsistent pressure, which further causes poor contact and overheating. Thermal deterioration spreads across all contacts. In addition, many disconnectors feature adjustable contact pressure; insufficient or inconsistent pressure adjustment will lead to the same defects.

At present, most maintenance personnel judge conductor contact status only by measuring loop resistance. They assume maintenance is qualified once the loop resistance meets standards. In fact, the loop resistance consists of terminals, conductive tubes and contact resistance, featuring wide tolerance ranges. It merely proves the circuit is conductive and cannot directly reflect variations of contact resistance. Tests verify that loop resistance can remain qualified regardless of whether two or four pairs of contacts are engaged. Similarly, varying contact pressure barely changes loop resistance.

Relevant maintenance codes and standards specify contact pressure measurement. Spring balances are the traditionally recommended tool, yet they are inconvenient, inaccurate and unsafe for high-altitude field work. For certain disconnector structures such as shear-type switches, contact pressure cannot be measured by spring balances at all.

a. GH6106A Disconnector Contact Pressure Tester measures and stores contact pressure data for all types of disconnectors rated 100kV and below. Data can be compared with standard values and historical records to draw conclusions and guide maintenance operations.
b. Test data can be uploaded to a computer and automatically exported as WORD or EXCEL documents for statistics and analysis.
c. Test reports can be automatically generated when operated with supporting PC software.