Draft technical article for editorial review. General educational information, not a site-specific procedure or safety instruction.
Verify the intended connection
Ratio and polarity tests confirm that the instrument transformer matches its intended circuit configuration. Wiring errors can affect metering accuracy and protection behavior even when an individual CT is healthy.
Assess the protection context
Excitation characteristics, winding resistance and secondary circuit burden provide additional evidence. Results should be evaluated against nameplate data and the requirements of the protection design.
Respect secondary circuit safety
Never open-circuit the secondary of an energized current transformer. Testing must be performed under an approved isolation procedure by qualified personnel using suitable instruments.
Connect knowledge with the right solution
Discuss the asset, operating history and testing objectives with an engineer before selecting a test scope or instrument.