Mission Brief

Prove the Eyes Before You Trust the Brain

A new 138 kV feeder bay is nearly ready to energize. Before the protection relay can be trusted, the CTs that feed it must be proven — a swapped polarity or a core that saturates too early makes even a perfect relay lie. Your job: run the full CT test card on the analyzer, read the excitation curve, and either clear the CT for service or condemn it.

• Verify turns ratio and polarity (S1/S2) of a protection CT
• Measure the excitation curve and derive the knee-point (IEC 10%/50%)
• Check the knee against the value the application requires (no early saturation)
• Confirm secondary winding resistance and connected burden
• Issue a pass/fail CT test record