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EHELP: I need to boost a 4-20mA HART signal...

EHELP: I need to boost a 4-20mA HART signal...

Q. I need to boost a 4-20mA signal to get a Fisher FIELDVIEW DVC6200 digital valve controller to respond to a control signal. What could I use?

A. The Fisher manual provides this basis:

“The input impedance of the DVC6200 active electronic circuit is not purely resistive. For comparison to resistive load specifications, an equivalent impedance of 550 ohms may be used. This value corresponds to 11V @ 20mA.”

Assuming you will need to be able to pass the HART digital component through the booster device since the DVC6200 can utilize it, Moore Industries offers the FS (Functional Safety) Series 4-wire SST Safety Isolator for this solution, it can drive up to 1000 ohms, pass critical HART data to asset management systems, allows you to program HART devices via hosts or handhelds, and has the additional benefit of being rated for SIS (Safety Instrumented System) applications.

The FS Series SIL 3 capable SSX 2-wire (loop powered) and SST 4-wire (line/mains powered) Safety Isolators and Splitters provide isolation and signal conversion have 1500Vrms isolating capability. The SSX/SST protects your safety I/O cards and system from harsh plant environments, surges, spikes, and transients in the field. Isolate your SIS from your Basic Process Control System or monitoring system so disconnections or failures to these secondary systems don’t affect your safety system. FMEDA (Failure Mode Effects and Diagnostic Analysis) reports are available with the required safety data to ensure that risk reduction requirements are met.

The SSX/SST feature:

  • exida certified IEC 61508:2010 for use in an SIS up to SIL 3
  • Valuable HART data is not lost, both the SSX/SST pass critical HART data to asset management systems, programming devices or host system
  • RFI/EMI Protection
  • Split signals between two locations with the 4-Wire SST - it takes in one signal and gives you two fully isolated outputs that can be taken to two separate receiving devices
  • Transmitter excitation - the 4-wire SST is capable of providing loop power to a 2-wire transmitter that is connected to its input

Learn more about the SSX/SST.

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Published: October 18, 2017
Categories: E-Help
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