UNITED ELECTRIC CONTROLS

TOPIC:

SIL 2 Certified / SIL 3 Capable
Safety Transmitters


The One Series Safety Transmitter used in Safety Instrumented Systems delivers the ultimate state-of-the-art diversity and redundancy required in these systems. It provides both affordable and highly reliable diversity along side either process transmitters or switches. The One Series Safety Transmitter is the first SIL 2 Certified / SIL 3 Capable transmitter designed solely for safety system applications. Only the One Series Safety Transmitter comes with an internal high-speed relay for the fastest emergency shutdown. That simple design means fewer nuisance trips — for greater safety, productivity, and throughput.


The One Series Safety Transmitter was designed with features that simplify installation, improve productivity, and eliminate nuisance trips. “I Am Working” sensor diagnostics with redundant data processing detect open, shorted, and plugged sensing elements.

The transmitter’s analog output conforms to the NAMUR NE 43 standard and provides process variable (PV) and detected-fault information. Discrete outputs provide a fail-safe (open) emergency shutdown when a fault is detected. Set point and deadband (reset point) are 100% programmable.

The instrument is password protected to prevent unwanted parameter changes; eliminating the risk of tampering. In addition, LED backlighting enhances viewing of process variables, parameters, and status in dimly lit areas.


 
  • Fewer nuisance trips for greater productivity
  • More affordable than adapting a process transmitter for SIS
  • Internal relay for faster emergency shutdowns
  • Higher safe failure fraction (98.8%) simplifies SIL achievement
  • 4-20 mA signal per NAMUR NE43 standard
  • Explosion proof for hazardous locations
 
 

   
   
 

 


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Namur NE43:

The Namur NE43 is a recommendation which gives a guideline how a sensor fault can be indicated to a control system by means of the 4-20mA signal.

Definition Namur NE43:

A sensor fault is signalled by extending the range of the 4-20mA signal. When the current is below 3.6 mA or above 21 mA this is interpreted as a sensor fault. In order to avoid false alarms the signal shall be present for at least 4 seconds before it is interpreted as sensor fault.

Advantage of Namur NE43
:

A process control system such as a PLC or DCS system can identify faulty sensors and production can be adjusted or stopped to avoid production loss or off-spec product. Also a maintenance technician can automatically be notified to repair or replace the broken transmitter.