Fatally flawed?

摘要

Products and systems used within E-STOP applications must fulfil the protective goals specified in BS EN 60204-1 and BS EN 418. Section 4.1.2 of BS EN 418 says, 'The control device and its actuator shall apply the principle of positive mechanical action'. This positive mechanical action (also known as positively driven or direct driven) is defined in BS EN 60947-5-1 (third part, sub clause 2.2) as 'the achievement of contact separation as the direct result of a specified movement of the switch actuator through non-resilient members (such as those not dependent upon springs)'.