1660338902109 Article 126 Fig1

Compact, high-functionality signal isolators

May 11, 2007
Many process control applications and systems require signal isolation and conditioning. The challenge is to provide these functions with compact, inexpensive and easy-to-use devices.


Pepperl+Fuchs meets these requirements with its new family of HiC signal isolators. The HiC isolators are each 12.5 mm wide, a substantial reduction in size from the 18-mm isolators in P+F’s HiD-Series.

The most common application for the HiC signal isolators is in intrinsic safety systems. Each isolator limits electrical energy as required for intrinsic safety installations. Another common application is isolation for inputs to and outputs from a distributed control system or a process automation controller.
The product family includes five signal isolators along with four ancillary components: an 8-channel termination board, a 16-channel termination board, a HART communications board and a fault monitor board. All of the boards mount on a DIN rail.

The isolators are fastened onto the mounting boards using a plug-and-lock installation requiring no tools or wiring. “When mounted directly onto our rugged termination boards, the C-Series provides the smallest system in the industry with single-loop integrity,” according to Robert Schosker, product manager at P+F.


Pepperall+Fuchs HiC signal isolators are SIL2- or SIL3-rated.

The five signal isolators provide the following functionality. A switch amplifier receives 1 Namur sensor/contact input and transmits 1 NO contact output for the signal and 1 NO contact output for signal/fault indication. A second switch amplifier receives 2 Namur sensor/contact input and transmits 1 NO contact output for the each signal.

A transmitter power supply/isolating converter receives a 4-20-mA signal input and transmits a 4-20 mA or 1-5 VDC signal output. This isolator is typically used in 2-wire, 4-20mA circuits.

An isolating converter receives and transmits a 4-20 mA signal. This isolator is typically used in 4-wire 4-20 mA circuits.

Finally, a valve control component receives and transmits a 24 VDC signal.

Each of the signal isolators is rated SIL2, except for the valve control component, which is rated SIL3. The two 4-20 mA isolators both feature HART communications capability.

HART communication is enabled by connecting one or more termination boards with up to 32 4-20 mA signal isolators to the 32-channel HART communications board. This allows a user to pick the HART signals from the HART communication board.

For example, a 4-20 mA isolator may be used to isolate the 4-20 mA signal from a HART-enabled field device to a DCS input board. The isolator passes the 4-20 mA signal through to the DCS and also makes the HART signal imposed on the 4-20 mA field-device output signal available for monitoring by a HART-enabled host.

Each of the termination boards requires 24-VDC power and can operate in a redundant mode if supplied with two 24-VDC power feeds.

Each termination board can be supplied with optional DCS connection configurations. “We can customize the termination board to a specific DCS manufacturer’s I/O card. For example if the customer was connecting to a Triconex 3700A I/O card, P+F would replace the terminal blocks on the safe side of the termination board with the appropriate Triconex connector. This would allow the system cable of the Triconex 3700A I/O card to plug directly into the board, eliminating manual wiring of every point back from the termination board to the I/O card. We have done this for Triconex, HIMA, ABB, Siemens/Moore APACS, Foxboro and other systems,” comments Schosker.

The fault monitor board is a termination board that provides LED indication and a contact output when a fault is detected for either a power or field signal failure. The fault monitoring board is connected to the 8- or 16- channel termination boards via external wiring. 

“The HiC series provides an ultra-thin housing for highly reliable industrial signal transmission and excellent system availability. The isolators are easy to service because they can be quickly fastened onto the termination boards without the need for tools or wiring. Even though tools are not required, the terminal system ensures that all connections are reliable,” adds Schosker.

  Product Exclusive Contact Information

For more information, contact Pepperl+Fuchs at 330-486-0002 or at [email protected]. Additional information is also available at www.us.pepperl-fuchs.com.

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