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Six safety relays replace 250 earlier devices
Published:  02 April, 2011

Rockwell Automation has unveiled a new generation of multi-function safety relays consisting of just six devices that replace 250 previous models. The GSR relays accept inputs from a variety of safety devices – such as light curtains, e-stops, interlocks and mats – and incorporate one or two safety inputs in their 22.5mm width, halving the cabinet space needed, and cutting the amount of wiring by 30–50%.

The new range is targeting the market for simple safety relays with basic AND/NOR logic functions for applications requiring up to four protection zones. In Europe alone, the market for safety relays is estimated to be worth around €151m.

The new relays’ logic functions are set using a rotary switch, without needing any software configuration. A recent survey revealed that 70% of users still prefer hard-wired relay-based protection to integrated systems.

A TÜV-approved single-wire safety connection between relays allows users to increase the number of outputs while maintaining SIL3/PLe safety integrity, thus reducing the amount of wiring needed. To simplify the wiring further, all input and power connections are at the top of the relays, and output and feedback at the bottom, thus avoiding the need for top-to-bottom wiring. All of a device’s wires can be kept in one tray.

Logic functions can be configured between relays and on dual-input versions, reducing design and installation time. The range also includes single-input versions.

Rockwell has produced freely downloadable software which can be used to simulate the operation of safety installations incorporating the new relays. There are also online animations showing how the technology works. Eplan macros are also available

Future enhancements planned for the range include: modules for special functions such as muting, back-emf, standstill monitoring and two-hand-controls; gateways for DeviceNet, Ethernet and I/O; and software-configurable relays which will be able to replace systems such as Sick’s FlexiSoft and Pilz’s PNOZmulti mini.

The new safety relays overlap with some existing Rockwell safety relays, such as the Minotaur range, but there are no plans to withdraw these at present. Rockwell estimates that the ability to use one relay where two were needed before will cut purchase costs by about 10%. Further savings will arise from the reduced stock requirements for the multi-purpose relays.

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