What is the purpose of cross-strapping power supplies in a multi-channel protection system?

• A. To reduce EMI on the system
• B. To calibrate sensors automatically
• C. To speed up trip processing
• D. To ensure independent operation of channels even if one power supply fails

Answer: (D)

Cross-strapping power supplies is about maintaining channel independence and reliability in a multi-channel protection system. By tying the power feeds of multiple supplies in a cross-linked arrangement, if one supply fails or sags, the other supplies can continue to power the affected channels. This prevents a single point of failure from taking down multiple channels and helps ensure each channel can still perform its protection function, preserving isolation and overall system availability. EMI reduction, automatic sensor calibration, and faster trip processing aren’t the primary goals here—the cross-strap arrangement focuses on keeping protection channels powered and operable even in the event of a power-supply fault.