STA SIL 2 and SIL 3 Compliant Programmable Current/Voltage and RTD/Thermocouple Safety Trip Alarms

The exida® SIL 2 and SIL 3 certified STA Safety Trip Alarm performs as a logic solver and acts on potentially hazardous process conditions; warns of unwanted process conditions; provides emergency shutdown; or provides on/off control in Safety Instrumented Systems (SIS) and traditional alarm trip applications.
The 4-wire (line/mains-powered) STA models accept a signal input from transmitters, temperature sensors and a wide array of other monitoring and control instruments including:

Current and Voltage Signals
Temperature (RTD and T/C) Sensor Inputs
Resistance and Potentiometer Devices
Direct Millivolt Sources


  • exida certified IEC 61508:2010. For systematic integrity up to SIL 3 and for random integrity up to SIL 2. This means that an STA is approved for single use in Safety Instrumented Systems (SIS) up to SIL 2 and in redundant architectures (1oo2, 2oo3, etc.) up to SIL 3.
  • Comprehensive FMEDA certified safety data. Upon request, exida-certified FMEDA (Failure Modes, Effects and Diagnostics Analysis) data is provided to be used by a competent functional safety practitioner to determine the STA’s applicability as a logic solver in specific safety-related applications.
  • 20-bit input resolution with long-term stability. Delivers industry-best digital accuracy with up to 5 years between scheduled calibrations.
  • Site-programmable with password protection. Front panel pushbuttons with menu-guided configuration deliver confident and secure set up.
  • Large 5-digit process and status readout. Backlit display shows menu prompts during configuration and, when in operation, shows the process variable, the output or toggles between the two in selectable engineering units.
  • Isolated and RFI/EMI protection. Delivers superior protection against the effects of ground loops and plant noise.
  • Combined alarm trip and transmitter. The analog output (-AO) option reduces costs and installation time when both alarm and transmitter functions are needed at the same location.