Clever signal integration solution for 4-wire transmitters in zone 1.

Hooking up a 4-wire transmitter to a 4-20 mA supply input is obviously problematic, since two power sources cannot usually be connected. For this scenario and other real-life challenges, R. Stahl has introduced the Ex i isolator series 9164.

Suitable for use in zone 1 hazardous areas and non-hazardous areas, this new generation of mA isolating repeaters enables a 4-wire transmitter connection via Ex i or Ex e signals. The devices boast a unique feature: their inputs and outputs act as passive current sinks and do not generate an active power signal of their own when converting an active into a passive 4... 20 mA signal. Notably, the isolating repeaters also allow for a bidirectional transmission of a superimposed HART communication signal.

Three versions are available. One version allows for galvanic isolation of two intrinsically safe circuits. With no Ex i output parameters and a relatively low voltage drop, it can be used for signal decoupling as well. That way, measured values can be passed on to other systems with ease.

A second version with an integrated fuse can be used to isolate an Ex e from an Ex i circuit. This type also enables users to connect an isolating repeater with increased safety type of protection to an Ex i input at a later stage, without the need for extra Ex e line installations.

The third type of module features identical functions for non-hazardous areas. The new isolating repeaters ensure extremely high accuracy and can be used in an ambient temperature range between -40 °C and +75 °C. While ATEX and IECEx certifications have already been procured, others for use all over the world as well as an assessment for use in functional safety applications (SIL) will follow soon.

• Stahl products are marketed in Ireland via Douglas Controls & Automation

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