What Does E-Stop Switch Mean?
An E-stop switch, otherwise known as an emergency stop switch, is a form of fail-safe control. When utilized, an E-stop switch halts the operation of associated equipment and shuts off all potential hazards outside of the equipment’s main power enclosure.
E-stops are typically integrated into the circuitry of a machine or electrical system so that if they are used, the circuit becomes disconnected and cuts off electrical power to the machine. This makes it physically impossible for the machine to be used until the switch is reset and the system undergoes restart procedures.
Safeopedia Explains E-Stop Switch
The purpose of an E-stop switch is to avert or reduce rising and existing hazards to persons, work, or machinery caused by the undesired activity of a machine or electrical system. The presence of a readily accessible E-stop switch on potentially hazardous or otherwise safety-sensitive machinery or controls is a legal requirement in all advanced jurisdictions. As such, E-stop switches must be designed to comply with legally recognized standards that lay out minimum usability and reliability criteria.
ISO 13850 is the most ubiquitously recognized standard describing the proper criteria and usage of an emergency-stop function. Under this standard, the use of an E-stop must be able to be initiated by a single human action during periods when a system’s normal stopping function is inadequate—either due to that normal stopping function being inaccessible, non-operational, or simply too slow for use in an emergency situation.
E-stop switches must function through manual control. The switch may be a traditional toggle-style switch or an alternative form of control device that is recognized by applicable standards. The most common form of E-stop is a push button, usually shaped as either a cone (Europe) or mushroom (North America). According to major consensus standards such as ISO 13850, IEC 60947-5, IEC 60204-1, and NFPA 79, all E-stop button switches must be colored red with a yellow background.
In addition to setting requirements for how an E-stop must function, consensus and government standards also set requirements for the type of systems that must be equipped with E-stops. For instance, CSA Z434-14 requires that all robot control systems provide emergency-stop functionality.
E-stops additionally have a preventative function. For instance, OSHA standard 1910.179, which concerns the use of overhead cranes, requires that emergency switches be open (activated) and locked into that position while the crane is being repaired. This prevents any of the crane’s systems from being accidentally activated during repair procedures.