Extension of the safety sensor series




The CSS 34 from Schmersal is the perfect, compact switchgear for the non-contact position monitoring of safety guards. Because of its small design, this safety sensor can be perfectly integrated in the surrounding construction. The four different actuating directions of the sensor enable universal applications.

Instead of a magnetic switch, the CSS 34 uses the innovative pulse-echo technology as operating principle, which tolerates a large guard professional door displacement. In this way, the user can use the intelligent electronics on board of the sensor to generate additional diagnostic information. Furthermore, multiple safety detectors can be wired in series and monitored by a common safety monitoring module – this practical feature saves costs and space in the control professional cabinet, without detriment to the safety level.

At Motek, Schmersal will present two new versions of the CSS 34. Though apparently not different from the current versions, these sensors however feature an essential advantage: they can execute additional monitoring functions. These sensors therefore can be used without safety monitoring module. The user can connect two conventional relays or professional contactors with positive-guided contacts to the safety outputs; the sensors then will monitor the safety-related function by means of a feedback circuit.

The new version F0, which is suitable for machines and plants with automatic start, does not monitor the edges of the contacts. If no automatic start is required, an enabling switch can be integrated in the feedback circuit. In the second new version, F1, a reset switch is required to monitor the trailing edge. This function is similar to the reset function on accessible safety guards.

Contrary to conventional safety monitoring modules, both versions of the CSS 34F additionally monitor the external wiring of the enabling switch or the reset pushbutton for cross-wire shorts, short-circuit to ground or frame and interference voltage. In this way, the “intelligent” electronics inside the CSS 34 is optimally used and control category 4 to EN 954-1 or SIL 3 to EN 13849 can be obtained without the need to use safety monitoring modules.

This is especially interesting on small machines with one safety guard, where the omission of a safety monitoring module represents a substantial cost saving. In case of multiple safety guards, this advantage is not that much preponderant, as the CSS 34 requires only one safety monitoring module for several series-wired safety sensors. This simplification is always enabled by the integrated electronics with additional functions. The series-wiring of these sensors (even in combination with other safety switchgear, such as the AZM 200 solenoid supplier interlock) now is even more enhanced: at Motek, Schmersal will present a new connector manufacturers, facilitating the daisy-chaining of the sensors.