Turck Banner, Banner Engineering's subsidiary in the UK, has introduced Pico-Guard, a new fibre-optic safety system that directly replaces mechanical safety interlock switches to safeguard potentially dangerous machines. This novel combination of reliable, non-contacting photoelectric and fibre- optic technologies provides a low-cost alternative to cumbersome and costly methods of machine safeguarding.
The concept is so simple, it beggars the question: why didn't anyone think of this before? As far as safety systems go, Pico-Guard is extremely versatile, efficient and easy to install. It combines a controller and various plug-in, snap-lock optical safety interlock switches and plastic fibre-optic cable, which can be installed much faster than conventionally wired, electro-mechanical systems to monitor doors, gates, and other machine access equipment. The transmitter and receiver elements are very compact and can be embedded into the machine guard framework to offer a much less obtrusive installation than would be the case with electro-mechanical devices.
There is no need to run electrical wiring to the machine or hazardous area. Durable fibre optic-cables can be easily routed to multiple machine guard points or hazardous areas, making conventional copper wires that carry electrical current to the guarded points no longer necessary. Pico-Guard installations are thus inherently intrinsically safe. Indeed, the system has ATEX approval for use in Zone 1 hazardous areas.
The controller offers four separate optical channels, each of which can control multiple optical safety interlock switches in the same optical network. Additional optical safety interlock switches can be added to any channel simply by inserting them into the fibre-optic loop for that channel. As soon as an optical beam is broken (opened door, for example), a stop signal is transmitted to the machine controller. Nuisance tripping is avoided as the system does allow for some degree of mechanical tolerance in hinges, door alignment, and so on, as well as any relative movement between transmitter and receiver due to machine vibration. The receiver has two solid-state safety outputs to control 24V dc loads or, alternatively, it can control forced-guided relays to provide isolated contacts.
Pico-Guard is ISO 13849-1 (EN954-1) Category 4 approved. It has been designed so that a single switch point per door will meet Safety Category 4 applications - an industry first, according to Turck Banner.