SIL 2 safety trip alarm

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The STA safety trip alarm is certified to IEC 61508: Parts 1, 2 and 3 by TÜV Rheinland and exida for single use in safety instrumented systems up to SIL 2. The STA firmware is suitable for a SIL 3 system, which allows the STA to be used in a redundant architecture (1oo2, 2oo3, etc) up to SIL 3.

The 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 SIS and traditional alarm trip applications.

The 4-wire (line/mains-powered) STA accepts a signal input from transmitters (current and voltage inputs), temperature sensors (RTD and thermocouple inputs), resistance and potentiometer devices, and a wide range of other monitoring and control equipment.

The STA provides three failsafe alarm outputs. Two are configurable process alarms that trip when a monitored process variable falls outside of user-set high and/or low limits. The third alarm is a non-programmable, latching alarm that is activated if any internal faults are found by the STA’s internal diagnostics. This fault relay is also triggered if the input is faulty or broken.

The STA features 20-bit input resolution; long-term stability of up to 5 years between scheduled calibrations; a rugged, industrial metal housing; and isolation and RFI/EMI protection that provides protection against the effects of ground loops, plant noise, and radio frequency and electromagnetic interference. The unit also features standard transmitter excitation to provide 24 V power to a 2-wire transmitter.

The trip alarm has been certified by exida for Safety Instrumented Systems to IEC 61508:2010 for systematic integrity up to SIL 3 and for random integrity up to SIL 2. The  STA is approved for single use in Safety Instrumented Systems up to SIL 2 and in redundant architectures such as 1oo2 and 2oo3 up to SIL 3.