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SIL 3 Capable SSX and SST Functional Safety Isolators from Moore Industries Provide Reliable Isolation for Analog and HART Signals

23 May 2017

Moore Industries’ SSX and SST Safety Isolators and Splitters provide reliable isolation and effectively pass valuable HART data in functionally safe process control settings. They are part of Moore Industries’ FS FUNCTIONAL SAFETY SERIES.

The two-wire (loop powered) SSX and four-wire (line/mains powered) SST have been certified by exida for use in a Safety Instrumented Systems (SIS) up to SIL 3 in monitor mode, where only the input circuit is part of the safety function.

For single use mode, the SSX/SST is approved for use in an SIS up to SIL 2. They join products from Moore Industries such as the STA Functional Safety Trip Alarm, the SRM Functional Safety Relay Module and STZ Functional Safety Dual Input Smart HART® Temperature Transmitters that have been developed following the strict IEC 61508:2010 standards for safety-related applications. 

The SSX and SST family protects safety systems by isolating an SIS from basic process control or monitoring systems so that disconnections or other failures don’t impact the safety system. It also has 1500Vrms of isolating capability to protect safety I/O cards and systems from surges, spikes and transients in the field. Standard 20V/m RFI and EMI protection stops damages caused by stray radio frequencies and electromagnetic interference.

Sending HART data is critical for diagnostic and preventative maintenance. While most isolators “strip off” HART data, the SSX and SST pass along HART data to asset management systems, programming devices or host systems. This lets site operators get the most out of their HART devices. In addition, the SSX stops ground loop noise and solves “bucking” power supply problems caused when two devices try to source power to the same loop.

The four-wire SST Splitter takes the input from one process signal and creates two identical, isolated outputs that can go to two different monitoring or control devices. It can also serve as a HART splitter to pass HART data to one or both independent outputs. This allows asset management systems to maintain a digital HART connection to critical valves and instruments. It also allows for handheld HART devices, modems or programming devices to easily configure remote field transmitters from control rooms.

The SSX and SST meet the high levels of reliability found in all products in Moore Industries’ FS FUNCTIONAL SAFETY SERIES. Along with its exida certification, comprehensive FMEDA-certified safety data is available on request. This information can be used by a functional safety practitioner to determine if the SSX and SST are applicable for use in their specific safety-related application.

The SSX/SST data sheet can be found at:

Moore Industries’ FS FUNCTIONAL SAFETY SERIES can be found at:

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