Fiber optics carrying light signals obviate the need to run current-carrying wires, which may generate EMI and have arcing potential, into hazardous areas. Taking these advantages, Banner Engineering has developed its PICO-GUARDTM safety system that can replace mechanical, magnetic, and RF-based safety interlock switches on dangerous machines. The system features plastic fiber cable and quick-connect photoelectric optical components to provide non-contact safety detection. Electronics are thus only at a central controller.
The optical controller is the heart and brains of the system. It features four optical channels, each of which can control individual or multiple optical switches (sensors) on the same network fiber loop for cost savings. The channels can be set for each to monitor a different zone of a machine, such as doors or guards. Once the system detects an absence of signal—that is, a break in an optical beam—it provides a stop signal to the machine within 13 msec of the beam being broken. "With the robustness of the optical switches to things like vibration, and the high repeatability in closing a guard, with no false 'closed' conditions or false trips, we get a high 'wow' factor from customers," says Mike Carlson, Banner safety systems engineer.
The company also developed a patent-pending Universal Safety Stop Interface to allow two or more controllers to daisy chain to guard a machine. The interface permits additional safety devices, such as emergency stop buttons, rope polls, and safety mats to be connected to the controller. "This gives the user the ability to easily integrate several safety functions into one stop signal without having to purchase additional safety relay modules," Carlson adds. Each controller has a latching connection for manual resettable devices and a tripping connection for automatic resets.
Future developments include presence sensing for whole-body detection using single or multiple beams.
For more information on PICO-GUARD from Banner Engineering Corp., enter 539 at www.designnews.com/info.
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