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Safety Installation Systems For Safety Switching Devices

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Safety Installation Systems For Safety Switching Devices
Safety Installation Systems For Safety Switching Devices

Video: Safety Installation Systems For Safety Switching Devices

Отличия серверных жестких дисков от десктопных
Video: What is a Safety Instrumented System? 2023, February

Here a safety switch, there a sensor for guard door monitoring, here a safety interlock: In more complex machines and systems, safety relays in various designs often have to be installed, installed and integrated into the safety circuit - a demanding task for the user. He therefore wants access to comprehensive information from the safety community, for example for fault diagnosis, as well as flexibility, since machines and systems are modernized, converted or relocated more and more during their life cycle.

Simplified installation of safety switching devices

"With conventional point-to-point connections between the safety switching device and evaluation unit or safety controller, these requirements or wishes can only be met inadequately. Safety bus systems like AS-i Safety offer more freedom here, but not every user wants to use this additional bus system,”says Udo Weber, Product Manager at the Schmersal Group. That is why Schmersal has developed a new type of component that makes it easier to install safety switching devices: the Schmersal Safety installation systems.

These installation systems are different components, all of which use a basic principle: The machine builder or the electrician does not connect the safety switching devices of the machine to the respective safety controller or the associated safety relay module, but to a separate wiring module that is located in the control cabinet or can be installed in the field. There, the signals are bundled and forwarded to the evaluation unit or the safety controller.

Like a safety bus system without a bus protocol

In principle, the installation systems thus function like a safety-related bus system - with the difference that no special bus protocol is used. The safety switching devices are permanently connected in series by the wiring modules for a safety function. According to Schmersal, this considerably reduces the wiring effort - and the user continues to use his existing safety evaluation unit.

A particular advantage should be that different electronic safety switching devices such as safety sensors and tumblers can be mixed in the respective application. "This is practical, because with larger systems, different machine areas often have to be protected with different safety switches," says Udo Weber. "The new system also offers cost-optimized variants for applications with only electronic safety switching devices."

Individual diagnosis possible

With the safety installation systems, individual diagnosis of the connected safety switching devices is also possible. “This means that the operator can see exactly which switch in the series connection triggered a signal. This way, any faults that occur can be eliminated more quickly and machine downtimes avoided,”explains the Schmersal product manager. The safety installation systems would thus contribute to increasing machine availability.

There are two different installation systems available for applications with only electronic safety switching devices: with a passive distribution module (PDM) and with a passive field box (PFB). They enable the mixed series connection of up to four different electronic safety switching devices per module. Several modules can be interconnected to form larger systems.

  • The passive PDM distribution module was developed for top-hat rail mounting, ie for installation in terminal boxes and control cabinets. It has a compact design, is easy to assemble and is also suitable for applications with increased hygiene requirements, such as in food processing and packaging machines.
  • The passive field box PFB is a plug & play solution in a robust IP67 version for decentralized use in a variety of industrial applications.

With the PDM and PFB modules, even larger safety systems can be easily wired because wire cross sections of up to 1.5 mm² can be connected. According to Schmersal, a unique selling point of these two solutions is the individual protection of the safety switching devices by means of line protection with a self-resetting fuse.

Active variant for safety switches and sensors

There is a third and active variant for safety switches and safety sensors: In the safe series connection of electromechanical safety switches with contact outputs or of safety sensors with electronic OSSD outputs, a safety input extension of the SRB-E series takes over the active electronic signal evaluation. With this solution, a safety level of category 4 / PL e / SIL 3 is achieved even with the series connection of contacts without reducing the diagnostic coverage, Schmersal states.

The passive installation systems PDM and PFB are optionally available in a variant for the "Serial Diagnosis" (SD) interface from Schmersal. It enables the serial transmission of the non-safe data and further reduces the wiring effort in a series connection. "Safety sensors and tumblers in the series connection, which are equipped with an SD interface, then transmit extensive diagnostic data to a controller via the SD gateway and a fieldbus," explains Udo Weber. In the case of the MZM100-SD non-contact magnetic safety locking device, this could be, for example, diagnostic data or error messages, such as "fault or cross-circuit at a safety output", "operating voltage too low" or "defective actuator". This enables quick troubleshooting.And the extended diagnostic functions would create the prerequisites for predictive maintenance in the sense of "predictive maintenance" and the avoidance of machine downtimes. (jv)

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