Emergency stop switched

Emergency stop switches could be provided in a safe position, adjacent to the aerials, to switch off the scanners and transmitters. 

Critical components are any components that may influence the safety of a product, such as those that operate at mains supply (120/230/400 Vac) or hazardous voltages (> 50 Vac or 60 Vdc). Examples of critical components are inlets, filters, switches, motors, circuit breakers, power supplies, and transformers. Components that may operate at lower voltages (i.e., 12 or 24 V) and may affect safety are also considered critical components and examples include emergency stop switches, door interlocks, relays, secondary fuses, thermal cutouts, fans, and sensors. 

Emergency stop (E-stop) switches, common to machinery and some products, use red mushroom buttons on a yellow background, which is universally recognized by operators and service personnel. E-stop devices have special requirements such as, positive opening, manual reset, fail-safe, and should be type-approved as E-stops (see Emergency Stop Switches section). 

There are several possible E-stops. The palm, or mushroom head type is the most popular. The actuator must be readily visible and easily reached by the operator from the working and operating positions. Several E-stop devices may be required to cover all the machines working or operating positions. The mushroom head or other actuator must be red and the background yellow to clearly identify the device as an emergency stop switch. A combined supply disconnect/E-stop device also exists and must meet all the E-stop and color requirements. The requirements for E-stops are defined in various standards, such as EN 60204-1 and EN 418. 

Mains Disconnect Switches 116 Emergency Stop Switches 117 Fault-Tolerant Components and Safety Circuits 117 Transformers 118 Motors 118... 

The most important measures to maintain fatality risk at the present level are the operating of the machine within safety limits , the existence of a properly functioning emergency stop switch and the use of technical measures against unintentional start-up of the machine such as lock-outs tag-outs on the machine while being maintained. If those measures are not respected or not used they will increase risk by 3.53, 2.33 and 1.62 times respectively. 

The most important measure to maintain permanent and recoverable injury risk is the operation of the machine within safety limits, the respect of the dangerous zone of the machine and the use of lock-out tag-out on the machine when the machine is being cleared. If not used they will increase risk by 4.7, 1.6 and 1.4 respectively. Absence of an emergency stop switch increases the risk of recoverable injuries additionally by 1.35 times. Results are shown in details in Tables 3 and 4. 

Arrest of dangerous machine motion resnlting from actuation of an emergency stop switch. The switch may be in the form of a safety switch, bntton, trip cable, or foot bar or other mechanical device used in conjnnction with an emergency stop safety module. Emission Control... 

An emergency stop switch shall be provided in the car and marked Stop. ... 

Emergency stop switches shall be arranged so that the conveyor cannot be started again until the actuating stop switch has been reset to running or on position. 

If for technical reasons the machine or process cannot accept intermittent movement, a continuous movement is permitted provided it is only at a predetermined minimum speed and is controlled by a hold-on switch, release of which causes fhe machine to stop immediately. Also, there should be only one such control operable on a machine at any one time and it should override all other controls except the emergency stop switch. 

A trip device is any device which, as the operator approaches the dangerous part, automatically trips the safety circuit. A simple flap trip is shown in Figure 4.3.13 but trip devices can include trip bars and wires, sensitive probes (on drilling machines), photoelectric devices, pressure sensitive strips and mats, and emergency stop switches. Figure 4.3.14 shows a pull trip switch on a conveyor. It is important that trip devices are properly adjusted and that the machine s brake is in good working order. 

A. collision switch (termed a collision emergency stop switch by the robot system manufacturer) is mounted around the welding head which will stop the robot when a collision between another object and the welding head is sensed. It operates via the hardwired emergency stop system. 

A person operating an electrically driven machine must have access to an emergency stop switch so that the machine can be stopped by that person in an emergency. See also 132.15 Isolation and switching below. 

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