I/O System How New Intrinsically Safe I/O Modules Redefine the Range of Application for Automation

Author / Editor: Benjamin Böhm, Manfred Kühme / Dr. Jörg Kempf

With its 750 XTR Series of products since 2014, Wago offers a solution that broadens the range of use for machines and systems with regard to environmental conditions and external interference factors, while providing the highest degree of flexibility. Now, Wago has defined a new dimension of use with the latest development for the 750 XTR Series.

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The new intrinsically safe I/O modules don't like it just hot or cold, but are also available for hazardous areas.
The new intrinsically safe I/O modules don't like it just hot or cold, but are also available for hazardous areas.
(Source: PRILL Mediendesign/Fotolia.com, Wago, [M]-Sahlmüller)

Engineers are constantly faced with the challenge of designing machines and systems as economically and effectively as possible, yet to develop a finished product for the world market. The jungle from import regulations as well as local standards and guidelines is a complex determinant. Much more obvious and at least as demanding are the different and sometimes extreme environmental conditions in which the equipment is used. Conditions range from moderate temperatures in Central Europe to strong temperature fluctuations between day and night in Central Asia, high humidity in Indonesia, extreme drought in the Andes to ice-cold Siberian winters.

Mobile systems must also cover as broad a range of applications as possible. A drilling rig may be deployed just of the coast of Brazil as in the high-lying deposits in northern Norway and Canada or in the middle of the Arabian desert. The same applies to the deck superstructures of tankers or cargo liners the maneuver on our world’s oceans.

Maximum Flexibility Beyond Zonal Boarders

With its latest innovation of the XTR Series, Wago provides a system that can be used for signals, for example, from non-hazardous areas that are intrinsically safe. The Wago-I/O-System 750 XTR can be used either outside of hazardous areas and within zone 2/22 inside an approved enclosure. All modules have Atex/IECEx approval for use in zone 2/22. Besides the standard signals from the sensors and actuators from zone 2/22, intrinsically safe sensors and actuators from zones 0/20 and 1/21 can also be integrated via the I/O modules in the blue enclosure.

The intrinsically safe part of the control system must be started with the Ex i supply module that regulates the input voltage of 24 V (–25 % to 30 %) to 24 V ± 0.3 V, limiting it to max. 26.8 V in case of failure. The module thus prevents ignitable sparks from occurring in case of failure.

To protect against possible interference from the non-intrinsically safe area of the control system, the Ex i power supply is installed in a wider housing that ensures required safety distance of 50 mm. The narrow 12 or 24 mm modules for digital and analog input and output signals, temperature measurements via resistance sensors and potentiometers or meter signals are connected to the Ex i power supply on the right.

Up to eight channels are available depending on the module. Up to three secondary variables can be read via the Hart protocol in addition to the main variables via one of the 2-channel analog input modules (750-484/040-000), thus paring down the number of measuring points required. Whether shut-off valve limit switches, slider magnetic valves or regulator valve control and position feedback, the 750 XTR Series provides the right intrinsically safe I/O module for every field device.