THE Allen-Bradley Guardmaster GuardShield is the next generation of safety light curtain available from Rockwell Automation Australia .
The general purpose system has been designed for point-of-operation, perimeter and access guarding on hazardous machinery and is configured with the flick of a DIP switch.
Featuring dual microprocessor controllers, GuardShield offers a selection of operating modes including fixed and floating blanking, beam coding (to prevent cross-talk between adjacent light curtains), start/restart interlock, and External Device Monitoring (EDM).
The EDM mode eliminates the need for a safety relay, as safety contactors up to 0.5A can be connected directly to the light curtain. DIP switches conveniently located on the transmitter and receiver end-caps permit easy configuration of operating mode, eliminating the need for a separate controller.
For applications where connection to a monitoring circuit is warranted, GuardShield features two PNP safety outputs for a safety PLC or safety relay, plus one PNP non-safety auxiliary output for connection of an additional device.
The current 'type 4' model of GuardShield is suitable for all high-risk applications and is rated to the category 4 safety standard with a 'type 2' version for lower risk applications available soon.
Two detection resolutions of GuardShield are available. Finger detection, at 14mm has a scanning range of 7m whil hand detection of 30mm has a scanning range of 18m.
Available protective heights range from 320mm to 1760mm, with a 160mm version, suitable for guillotine guarding to be released in early 2004. Response time for machine shutdown is 20ms, meaning that the safety light curtain can be mounted close to the hazard it is guarding against.
An extruded single-piece aluminium housing gives the GuardShield high strength for its light weight, which provides resistance to twisting, plus meets the IP65 enclosure rating for dust and water resistance.