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Pepperl+Fuchs Blog

Thermocouples and Galvanically Isolated Intrinsic Safety Barriers

Posted by Aaron Severa on Fri, Oct 12, 2012

A match made for hazardous areas

A very common application we see working with intrinsic safety is one involving the use of a thermocouple. Pepperl+Fuchs has a wide variety of galvanically isolated intrinsic safety barriers that will work with these devices.

When in a hazardous location and working on selecting a barrier, the first question that needs to be answered is, “What type of signal(s) are you looking for on the control side of the barrier?” Once that question is answered, you can begin the process of selecting a barrier.

The first type of galvanically isolated barrier that we offer is a straight, low-voltage repeater: the KFD2-VR2-Ex1.50M. This barrier is powered by a 24 VDC supply and will simply repeat a 0 mV to ±50 mV signal from a thermocouple. There is no configuration required for this barrier.

The second option we have is our KFD2-UT2 series. These barriers will take a thermocouple input and convert the mV signal into a corresponding current or voltage signal, depending on the selection. The UT2 series of temperature converters is programmable via our free-to-download PACTware software and the use of an adapter cable (RS232 or USB options available) that must be purchased as an accessory. We offer these barriers in a few options:

KFD2-UT2-Ex1 --- Single channel, 4 mA … 20 mA output
KFD2-UT2-Ex1-1 --- Single channel, 1 V … 5 V output
KFD2-UT2-Ex2 --- Dual channel, 4 mA … 20 mA outputs
KFD2-UT2-Ex2-1 --- Dual channel, 1 V … 5 V outputs

The third option, the KFD0-TT-Ex1, is also classified as a thermocouple converter, which will take the mV signal input and convert it into a 4 mA ... 20 mA output. This specific barrier requires no outside software or programming cable to set up. All of the adjustments are made with DIP switches and fine adjustment potentiometers on the barrier.

The next barrier we offer is our KFD2-GU-Ex1 model. This barrier provides two Form C relay contacts that will be used as high- and low-temperature trip points that are user programmed. Once again, this barrier will require the use of PACTware and the adapter cable.

The last galvanically isolated barrier we offer for thermocouple applications is our KFD2-GUT-Ex1.D barrier. This is the most advanced barrier in the series and is basically a combination of the features on the “UT2” and “GU” barriers. It will provide two Form C relay contacts along with a 4 mA … 20 mA current output. The barrier can be programmed via a small keypad and LC display on the front or by using the PACTware software.

As with any of our K-System barriers, all of the above barriers have removable terminal blocks. As a separate accessory, we offer a terminal block that has built-in cold junction compensation for use specifically with thermocouples, the K-CJC-BU. This terminal block has an integrated encapsulated Pt100 RTD that is used for cold junction compensation, eliminating the need to maintain a known reference temperature.

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Topics: Intrinsic Safety Barriers, Intrinsic Safety

Understanding Line Fault Detection with Intrinsic Safety Barriers

Posted by Barbara Vazquez-Isla on Thu, Oct 04, 2012

Monitor lead breakage and detect short circuits with IS barriers

Discrete input signals send an "on" or "off" signal from devices such as a pushbutton, switch, or contact. When the application requires an intrinsically safe circuit, the typical circuit consists of a field device, an intrinsic safety barrier, and a controller (DCS or PLC).

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Topics: Troubleshooting, Intrinsic Safety Barriers

Float Switches and Intrinsic Safety Barriers

Posted by Aaron Severa on Wed, Sep 05, 2012

Best choices for a Zone 1 application?

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Topics: Ask an Expert, Intrinsic Safety Barriers, Level Sensors

5 Questions Answered: Intrinsic Safety Barriers

Posted by Zach Lohr on Wed, Aug 22, 2012

Question one

I have a KFD2-UT2-Ex.1 and would like to know what software/hardware I need to have?

A) The PACTware software and interface technology DTM software are free and can be downloaded from our website. One nice thing to point out is all Pepperl+Fuchs intrinsic safety barriers use the same DTM. You will also need a cable to configure a barrier. You can use either the K-ADP-1 (RS-232) or K-ADP-USB (USB).

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Topics: Ask an Expert, Intrinsic Safety Barriers, Zener Barriers

Configuring the Intrinsic Safety Barrier KFD0-TR-Ex1

Posted by Aaron Severa on Tue, Aug 07, 2012

The KFD0-TR-Ex1 is an RTD converter

What you will want to do to fine tune this intrinsic safety barrier is as follows:

Look at these RTD Resistance Tables (PDF). The temperature value corresponds with the resistance values for the RTD.

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Topics: Troubleshooting, Intrinsic Safety Barriers

The Basics of an Intrinsic Safety Barrier

Posted by Kristen Barbour on Tue, Jul 24, 2012

IS barriers protect devices in hazardous areas

An intrinsic safety barrier is used to provide protection to a device mounted in a hazardous location. The basic components that make up most intrinsic safety barriers are a fuse, zener diodes, and a resistor and are shown below in this simple electrical diagram:

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Topics: Intrinsic Safety Barriers, Intrinsic Safety

Should I Use a Galvanic Isolation Barrier or a Zener Barrier?

Posted by Kristen Barbour on Wed, Jun 27, 2012

Galvanic isolation is often identified with an intrinsic safety isolator

In the context of this question, let's compare an intrinsic safety isolator and a zener diode barrier.

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Topics: Ask an Expert, Intrinsic Safety Barriers, Zener Barriers

How to Configure the Intrinsic Safety Barrier KFD0-TT-Ex1

Posted by Aaron Severa on Tue, Jun 12, 2012

The KFD0-TT-Ex1 is a thermocouple converter


What you will want to do to fine tune this intrinsic safety barrier is as follows:

Look at these thermocouple tables. The temperature value on the left side corresponds with the mV values for each type of thermocouple.

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Topics: Troubleshooting, Intrinsic Safety Barriers

Intrinsic safety barriers and field instruments

Posted by David Hohenstein on Fri, Jun 01, 2012

 Does a field instrument need to be rated IS when it’s used with an intrinsic safety barrier?

If we make the obvious assumption that the area classification in which the field instrument is mounted is rated Class I, Division 1, the answer is YES. The instrument must be intrinsically safe if it’s connected to an intrinsic safety barrier. An

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Topics: Intrinsic Safety Barriers, Intrinsic Safety

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