Safety relay
24 October 2008
Mitsubishi's safety relays closely integrate the stand alone protection and performance of safety circuits and the diagnostic capability of the PLC either by incorporation of the QS safety relay onto the PLC rack, or by direct high speed CC-Link for the stand alone networked version.
Safety relay
Detailed intelligence is instantly available on the operational condition of the safety relay as well as the status of each of the connected safety circuits, thereby allowing rapid identification of safety conditions on the plant.
Tripped circuits can be instantly identified at the control system. This information can then be visualised by HMI, Scada or simple panel indicators which dramatically reduce the circuit search and locate time. A history of trips and their causes can be logged and analysed, leading to identification of recurring issues which can thus be addressed.
The QS is powered independently from the PLC, So if the PLC fails it does not affect the safety circuit, this stays independent protecting man and machine come what may.” The key advantage however of either integrating the QS with the PLC rack data bus, or by connecting the stand alone version via CC Link, is that detailed safety circuit status can be easily transmitted to the control system. This feature cannot be replicated using traditional safety relays, where basic tripped status is all that can be derived.
The QS is certified by TUV, and covers EN954-1, Category 3 and Category 4 installations. It has also been certified to the new EN ISO13849-1 standard and meets performance level “e”.
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