Accuracy and temperature
Sustained overload can increase measurement error and heating in instrument transformers. Abnormal noise may indicate loading, loose components or insulation-related problems that need investigation.
Secondary-circuit faults
Open CT secondary circuits and short-circuited VT secondary circuits present different hazards. Loose wiring and failed protective devices may also interrupt the signals used by meters and protection relays.
System-level consequences
Loss of a voltage or current signal can affect protection performance. Inspection, fault assessment and any change to protection arrangements belong within the approved maintenance procedures for the installation.