Thermal processes with sensors in hazardous areas need immediate protection and certified input safety. The STL50Ex switches the system to a safe operating state without delay if the permissible temperature limit is reached or a monitoring fault occurs.
The intrinsically safe input supports Pt100 3-wire sensors and double thermocouples J, K, N and S, with marking II (1) G [Ex ia Ga] IIC/IIB and II (1) D [Ex ia Da] IIIC. The device operates as STB safety temperature limiter, STW safety temperature monitor or ASTB exhaust gas safety temperature limiter, with maximum or minimum monitoring and switching hysteresis towards the safe range.
Error causes appear in plain text on the graphic LCD display, are stored in memory and are indicated by the ALARM LED plus a 24 V DC external alarm signal. Certifications to EN 14597, EN 61508 SIL2 and EN ISO 13849 PL d support use in safety-relevant thermal processes.
The device can be configured as STB, STW or ASTB, with maximum or minimum monitoring depending on the selected safety task.
The input supports Pt100 in 3-wire connection or double thermocouples Type J, K, N and S for hazardous-area temperature sensors.
The main relay is a forcibly guided SPDT relay for the safety-relevant temperature limit and switches to the safe state in fault conditions.
Versions with 2RAO output include a pre-alarm relay for additional signaling before the safety limit is reached.
The 2RAO version includes a galvanically isolated 0/4..20 mA or 0/2..10 V output with load-dependent automatic changeover.
A contact input allows reset via an external button after fault elimination in limiter operating modes.
Password protection restricts access to safety-relevant configuration parameters and helps prevent unauthorized changes.
The PA6.6 housing mounts on TS35 carrier rail and uses screw terminals from 0.14..2.5 mm².
