An emergency stop button is a button that is used only when the functions of a machine need to be halted immediately. These buttons can be pressed when anything regarding the machine's functions or the operator's surroundings pose a threat to production or safety. They put an end to a machine's current functions, so other machines related to the stopped one might also have to modified when the button is pressed.
As a safety measure, emergency stop buttons are a critical part of potentially dangerous machines that contain electrical circuits. They can be found on gas pumps, saws, mills, cutting devices, and other moving machinery used for industrial purposes, such as conveyor belts. The more complex the machine, the more likely that it will have an emergency stop button. These buttons typically work by cutting off power to the circuit that provides electricity to the machine.
The button is wired into the machine's main and normal circuitry. Once it is pressed, it breaks and opens the circuitry, which, in turn, cuts off the electrical supply and shuts down the machine. The electrical power supply is interrupted and causes the machine to halt its functions immediately.
A standard stop button shouldn't be confused with an emergency one. Stop buttons are usually located next to start buttons and are generally of comparable size to the start button. An emergency button is usually much larger and more obvious, and it's often red. It can be made of metal or plastic and can also come in different forms to suit a particular machine. For example, they can vary in position and release styles; some can require key, push-pull or twist releases. Depending on the size of machine, multiple emergency stop buttons could be found on a single machine.
Operators should be aware that using an emergency stop button can result in the complete shutdown of the machine. Should an operator decide to restart the machine's functions, he or she might have to reset the machine and the stop button manually. After this occurs, the electricity circuit that powers the machine can be closed and restored to full operation.