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An emergency switch in Japan. On railways, [1] an emergency stop is a full application of the brakes in order to bring a train to a stop as quickly as possible. [2] This occurs either by a manual emergency stop activation, such as a button being pushed on the train to start the emergency stop, or on some trains automatically, when the train has passed a red signal or the driver has failed to ...
Safety relays must always be designed in such a way that, if wired correctly, neither a fault in the device nor an external fault caused by the sensor or actuator will lead to the loss of the safety function. [8] A normal relay uses a wire coil and the mechanical movement of the metal contacts to switch the load on and off.
Its function is distinct from that of pressure relief valves, which are passive devices opening if pressure reaches a value above the process safety trip, but still below the design pressure of the equipment. Relief valves complement the PSD. A process plant is typically divided into isolatable sections by emergency shutdown valves (ESDVs).
Interest in dead man's controls increased with the introduction of electric trams (streetcars in North America) and especially electrified rapid transit trains. The first widespread use came with the introduction of the mass-produced Birney One-Man Safety (tram) Car, though dead-man equipment was fairly rare on US streetcars until the successful PCC streetcar, which had a left-foot-operated ...
In electric power systems and industrial automation, ANSI Device Numbers can be used to identify equipment and devices in a system such as relays, circuit breakers, or instruments. The device numbers are enumerated in ANSI/IEEE Standard C37.2 Standard for Electrical Power System Device Function Numbers, Acronyms, and Contact Designations.
To make a PLC fail-safe the system does not require energization to stop the drives associated. For example, usually, an emergency stop is a normally closed contact. In the event of a power failure this would remove the power directly from the coil and also the PLC input. Hence, a fail-safe system.
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SCRAM button at the Experimental Breeder Reactor I in Idaho. Sometimes the switch will have a flip cover to prevent inadvertent operation. A scram or SCRAM is an emergency shutdown of a nuclear reactor effected by immediately terminating the fission reaction.