Emergency Stop (ESTOP): The specific control function of Emergency Stop is defined in industry standards such as NFPA 79, Electrical Standard for Industrial Machinery. Other references include ANSI documents such as B11 and B20 which specifically deal with mechanical equipment and conveyor systems. Various categories of Emergency Stop are defined to accommodate different situations and levels of severity. One characteristic of estop systems is that the function becomes latched until manually reset by a human operator, and that the reset does not automatically restart the affected equipment.
A common issue with control system design is to improperly mix emergency stop functions with those of lockout-tagout procedures. Each function serves a different purpose and must be properly coordinated in both design and operation. An article addressing the combination of LOTO and E-Stop can be viewed here.
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