Overall dimensions and technical information are provided solely for informative purposes and may be modified without notice Air service units Series Airplus 2 AIR TREATMENT 2 | 78 Installation tip of a safety system by means of a single valve Please note: the safety valve is not sufficient alone to guarantee the safety function. Its setup requires the use of a monitoring device. In this setup, the SIEMENS® 3SK1112-1BB40 monitoring device has been indicated, activated by an S2 start / reset pushbutton, blocked by an S1 emergency shutdown key. Said monitoring device, by means of the readings of the sensor placed inside the valve (reading made by means of the K1 relay), operates the activation of the valve itself. The monitoring device transmits the safety status as an output. The preliminary estimate and the final verification of the achieved PL are the responsibility of the designer of the part of the system dedicated to providing the safety function. Note: with a single valve, it is not possible to obtain a PL greater than “c”. Setup suggestions • The double stop pushbutton is connected to clamps T1-IN1 and T2-IN2 of 3SK1112-1BB40. • The start / reset pushbutton is connected between +24 V and the INS clamp of 3SK1112-1BB40. • The valve is supplied between 0 V (Pin 3 of the supply connector) and the 14 clamp of 3SK1112-1BB40 (Pin 2 of the supply connector). • The HALL effect sensor is supplied between 0 V (Pin 3 of the supply connector) and 24 V (Pin 1 of the supply connector). • The HALL effect sensor drives (Pin 4 of the supply connector) the K1 relay, whose N.A. contact will be connected between the monitoring device’s clamp T2 and INF. The circuit diagram of the suggested configuration is provided, along with the configuration of 3SK1112-1BB40. Analysis of malfunctions The diagnostic system (monitoring device plus sensor) has the purpose of verifying the appearance of malfunctions within the valve that undermine the safety function. In particular, (with 3SK1112-1BB40 configured as in the illustration), the K1 relay prevents resetting the system by means of S2 when the coil is de-energised, but the sensor remains in the OFF position (K1 remains de-energised). 24 VDC 0 VDC 1 3 2 G EV 1 A2- A1+ T1 IN1 T2 IN2 INS 13 14 INF 41 42 K1 3SK1112-1BB40 S1 K1 S2 BLUE BROWN BLACK STATE 3SK1112-1BB40 Configuration 1 Autostart / Monitored Start 2 Cross fault detection OFF / ON 3 2 single-ch. sensors / 1 double-ch. sensor 4 Startup test YES / NO
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