United Electric Controls (UE) adds two DC-voltage switching models to its One Series Safety Transmitter (ST) line. With its ability to directly switch 24 VDC and 125 VDC as well as 250 VAC loads, the One Series ST models can now provide SIL 2-certified control for many types of final elements including pilot valves, actuators, motor controllers and other SIS elements, without involving a DCS or safety PLC, according to the company.
One Series safety transmitters embed a process sensor, logic solver and safety relay in a single, SIL 2-certified field device. Although it looks like a traditional temperature or pressure transmitter, the ST can also switch final elements such as valves, motors and blowers directly from the transmitter, maximizing response time while eliminating the wiring inherent in having to route a shutdown or alarm response through a PLC or another safety controller.
United Electric Controls adds a Safety Relay Output (SRO) capable of handling 0-30 VDC at 6 amperes. To meet the needs of customers who were using 125 V DC equipment, most of whom are in the power industry, UE adds an SRO capable of switching 0-130 VDC at 2.5 amperes. According to UE, One Series Safety Transmitters models can now be specified for either pressure or temperature monitoring at any of the following current levels:
• 12-250 VAC @ 5 mA-5 A (Model 2SLP47)
• 0-30 VDC @ 6 A, 1.8 A Pilot Duty (Model 2SLP48)
• 0-130 VDC @ 2.5 A, Q1501 Pilot Duty (Model 2SLP49)
All One Series Safety Transmitters provide 4-20 mA NAMUR NE 43 standard output with exclusive “I Am Working” diagnostics. The transmitters are certified for use in SIL 2 safety instrumented systems and are capable of SIL 3, per IEC 61508. They have configurable self-diagnostics and reportedly achieve a safe failure fraction of 98.8%. Additional low-level discrete outputs communicate health and set point status. Instrument response time is <100 milliseconds, according to the company.