The core of maintaining combined instrument transformers involves regular visual inspections, checks on wiring and insulation, and proper cleaning, while strictly adhering to the fundamental safety rules: current transformers must not be open-circuited, and voltage transformers must not be short-circuited.
Visual and connection inspection: Check connectors for signs of overheating or discoloration, loose screws, or burnt odors; inspect porcelain bushings for cleanliness and check for damage, cracks, or discharge marks.
Operational status monitoring: Verify that three-phase voltage (or current) readings are within permissible limits and assess whether the unit is operating under overload conditions; listen for abnormal sounds indicating internal discharge or mechanical vibration.
Insulation and grounding inspection: Periodically verify insulation integrity; check secondary windings for open circuits (or short circuits) and ensure grounding connections are secure, free from looseness or breakage.
Cleaning and maintenance: Regularly clean the exterior using dry cleaning tools to prevent the accumulation of contaminants that could trigger electrical discharge.