ONPOW Clarifies Emergency Stop Circuit Design
Manufacturer ONPOW has released a guide for reviewing dual-channel NC circuit diagrams for emergency stops. The guide emphasizes that normally closed contacts alone do not ensure machine safety.
ONPOW Push Button Manufacture Co., Ltd. has released guidance on the design of emergency stop circuits. The guide specifically addresses the use of dual-channel, normally closed (NC) contacts and the interpretation of diagrams to ensure machine safety.
The company emphasizes that a red emergency stop button and a broken wire alone are insufficient. Achieving a safe machine requires careful design of contact states, safety input channels, reset conditions, controlled outputs, and feedback. ONPOW stresses the importance of first conducting a machine risk assessment and adhering strictly to safety controller instructions. A dual-channel diagram can aid review, but two NC contacts by themselves do not guarantee safety.
The manufacturer reminds users that the emergency stop function is part of a broader risk reduction strategy and does not replace guarding, safe access procedures, or energy isolation. The design must differentiate between normal stopping and emergency stopping, and the technical specifications and contact configurations for each component must be confirmed from manufacturer documentation. ONPOW specifically urges users to request the exact ordering code, wiring diagram, and applicable documentation before approving a component for a safety-critical circuit.
The guide details how to read button contacts in their defined state, what the two channels should check, and how reset and restart are handled as separate actions. The company cautions against generalizing fault detection and urges clear documentation of design assumptions, as well as separating safety input channels from ordinary indication or process control circuits.