Isolator & Barrier

Isolators and barriers are the interface modules between field instruments and the control system. Intrinsically safe isolators limit the energy sent into a hazardous area, and signal isolators and converters separate, convert and repeat signals in the safe area. Seven Star LLC supplies these modules to instrument engineers in Oman, with MTL isolating barriers and repeater power supplies, Pepperl+Fuchs K-System and H-System modules, R. STAHL Ex i modules, PR electronics universal converters, Moore Industries signal isolators and Phoenix Contact surge protection.

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About Isolator & Barrier

19 products 6 brands

Types of isolator barrier in this category

Most items are galvanic isolators, which combine energy limitation with electrical separation between the field circuit, the control system and the power supply. By function they divide into repeater power supplies that feed a two-wire transmitter and repeat its 4-20 mA signal, often passing HART through, temperature converters that take thermocouple or RTD inputs and give a linear current output, digital output modules that drive solenoids and alarms in the hazardous area, and fieldbus barriers that feed intrinsically safe spurs on a fieldbus segment. Universal converters such as the PR electronics 4116 and 9116B accept many input types and are set up by configuration. Surge protectors divert lightning and switching transients and are fitted on long outdoor cable runs.

Zener barrier or galvanic isolator, and other selection points

A Zener barrier is a passive shunt-diode device that needs a dedicated intrinsic safety earth. A galvanic isolator needs no such earth and keeps the field loop floating, which is why it has become the usual choice in new plants across the GCC. Selection then follows the loop: signal type, number of channels, hazardous-area gas group, and the entity parameters. The Uo, Io and Po of the isolator must not exceed the Ui, Ii and Pi of the field device, and the cable capacitance and inductance must stay within Co and Lo. For loops in a safety instrumented function, check the module’s SIL capability in its functional safety manual. The mounting system matters too: DIN-rail modules and termination-board modules are not interchangeable.

What to send for a signal barrier quotation

Send the full model number. Without one, give the signal type, the field device and its hazardous-area marking, the number of channels, supply voltage and mounting style.

What to include in your inquiry

These details let us quote the right item the first time.

Full part number or order code
Hardware and firmware revision, when replacing a part
Control system or PLC family it must work with
New installation or replacement of an obsolete part
Quantity and required delivery date

Missing some of them? Send what you have. A nameplate photo or an old part number is enough to start.

Brands in Isolator & Barrier

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Guides and articles

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Hazardous Area Classification Explained: Zones, Gas Groups, Temperature Classes and Choosing Ex Equipment

Request a Quote for Isolator & Barrier

Looking for a specific model, part number or brand in Isolator & Barrier? Send us your requirements and quantities. Seven Star LLC sources genuine industrial equipment for customers across Oman and the GCC and replies with a formal quotation.

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Frequently Asked Questions

What is the difference between a Zener barrier and a galvanic isolator?

Both limit voltage and current to the hazardous area. A Zener barrier does it with diodes and resistors and diverts fault energy to a dedicated, low-resistance intrinsic safety earth, which must be maintained. A galvanic isolator uses a transformer or optical separation, needs no special earth, tolerates earthed field sensors and avoids ground loops. Isolators need a power supply and are the more common choice today.

How do I check that a barrier is compatible with my field transmitter?

Compare the entity parameters on both certificates. The isolator's maximum output voltage, current and power (Uo, Io, Po) must each be equal to or lower than the transmitter's permitted input values (Ui, Ii, Pi). Then add the cable capacitance and inductance to the transmitter's internal values and confirm the totals are within the isolator's Co and Lo for the gas group.

Can I replace an MTL isolator with a Pepperl+Fuchs module, or the reverse?

Functionally equivalent modules exist, but it is not a drop-in change. The terminal layout, housing width and power rail differ, and the intrinsic safety loop calculation has to be repeated with the new module's entity parameters and documented. For a SIL loop the safety data change as well. Send us the existing model and loop details, and we identify the candidate for your engineers to verify.

Does a signal isolator need to be HART transparent?

Only if you use HART communication through it, for example with an asset management system or a handheld communicator connected on the safe-area side. A HART-transparent repeater passes the digital signal in both directions along with the 4-20 mA value. If the loop only uses the analog signal, a standard repeater works, but choosing a transparent type keeps the option open.

What information is needed to quote an intrinsically safe isolator?

The model number is the surest route. Otherwise tell us the signal (transmitter supply, current output, thermocouple, RTD, switch or solenoid), the number of channels, the field device model and its Ex marking, the gas group, the supply voltage, required SIL capability, and the mounting system, DIN rail with or without power rail, or a termination board.

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