What is a start interlock in a multi-motor system?

• A. It prevents starting one motor while another is running to avoid simultaneous operation.
• B. It ensures all motors start together for efficiency.
• C. It delays start until manual approval.
• D. It monitors motor temperature during startup.

Answer: (A)

A start interlock prevents starting one motor while another is already running, so only one motor can start at a time. This sequencing protects against large inrush currents, voltage drops, and mechanical stress that can occur if multiple drives try to start simultaneously. In practice, the control circuit uses interlocking logic (relays or PLC logic) to keep the start command blocked for any motor whenever another motor is running, until the running motor finishes or is stopped.

The other ideas describe different protections or control actions that aren’t about sequencing starts. It wouldn’t ensure all motors start together, it wouldn’t require manual approval to start, and it isn’t about monitoring temperature during startup.