Understand the interface decision

A coil can lose supply, a mechanism can fail to move, or contacts can remain in an unintended state. The design needs to specify what the feedback represents and how disagreement is handled. An auxiliary contact must be suitable for the credited diagnostic function.

A rotating wind turbine can retain mechanical input while electrical conditions change. Define the complete control action and energy destination together. A component-level response is only one part of the system-level protective function being assessed.

Put these inputs in the review record

Use a project-specific worksheet to capture the following information. For each entry, name the document, revision and person responsible for resolving any uncertainty.

• Contactor command, power-contact function and feedback-contact identity. Identify the exact configuration and the supporting document.
• Expected transition timing and diagnostic conditions. Keep the design assumptions visible in the project record.
• The response to failure to open, close or agree with the command. Name the responsible reviewer and resolve any missing information.
• Any independence or safety characteristics credited by the design. State how this entry will be verified during acceptance.

Define the acceptance boundary

Accept the feedback scheme against the required diagnostic coverage, not simply the presence of an extra wire. Define which mismatch prevents operation or restart. The actual protective response must remain suitable for the turbine’s energy state.

A useful functional test records command, feedback and resulting system state together. Keep simulated-feedback tests distinct from tests that verify the actual contactor mechanism and the related power circuit.