Conveyor systems often contain danger zones which must be protected against unauthorised access. However, goods/product must be able to enter and exit the danger zone. Examples of systems such as this can be found in intralogistics and in the automotive and packaging industries. In practice, the safety requirements are met using optoelectronic protective devices. These protective devices must be designed so that they detect the approach of the goods/product and then temporarily bridge the protective field to allow the goods/product to pass through but detect a person and emergency stop the system should they try to access the danger zone.

Additional sensors are required for detecting the goods/product – and therefore also for distinguishing between goods/product and people. These are referred to as ‘muting sensors’. The “Smart Process Gating” (SPG) principle meets the above mentioned requirements without the need for additional sensors and therefore conveyor systems can be made more compact.

The risk of misalignment or damage to the sensors is eliminated as are the costs for their maintenance and servicing. Furthermore, the purchasing costs, the wiring and risk of manipulation are reduced which increases the reliability of the complete safety device. Particularly in the case of typical intralogistics applications, the height of the protective device is entirely dependent on the safety-related requirements. Synchronisation beams do not have to be taken into consideration. With SPG, the first muting signal comes from the process control (PLC), while the second muting signal is generated by the protective field itself.

Smart Process Gating requires a detailed knowledge of the process so that the necessary SPS control signals are made available in the expected time window. The “Smart Process Gating” muting process, which completely removes the need for muting sensors, is based on the MLC safety light curtains from Leuze electronic and is integrated in the MLC 530 SPG model. The MLC 530 SPG safety light curtain specification is designed in accordance with the safety relevant, international standards and is type 4 (IEC/EN 61496), performance level PL e/ category 4 (EN ISO 13849-1) and SIL 3 (IEC 61508).

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