Photoelectric safety systems

Some safeguarding devices are used to detect the presence of people and to trip the machines they safeguard. The main two to be described here are photoelectric safety systems and laser scanners, which are both types of active optoelectronic electrosensitive protective systems. Pressure sensitive devices such as pressure mats and trip bars are other types of trip device. 

In defining which material to include in Objective 3.3, no fixed requirements have been used. As an example, some guidelines on protective devices (e.g. photoelectric safety systems) have been included, but a systematic collection has not been attempted. Similarly, other material not being of primary importance or unique to PESs has only been covered sporadically. 

Photoelectric safety devices are safety components , as defined in the Supply of Machinery Safety Regulations 1992. A notified body, who will use BS EN 61496 as the baseline standard, must therefore check their conformity with the Regulations. The standard lays down general requirements for electrosensitive protective equipment, in Part 1, with Part 2 specifying particular requirements for photoelectric systems. For example, the standard specifies two types of device according to their fault tolerance. Type 2 and Type 4 ... 

The interfacing arrangement between the electrosensitive protective equipment and the machinery control system is a particularly important facet of the safety system s design. It is the overall control system incorporating both the photoelectric guard and the machine s safety-related control system that determines the level of safety that can be achieved. Close attention therefore needs to be paid to the machine s control system and the way in... 

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