What Does 2-WISE Mean – and Why Is It Helpful for Ethernet-APL Installations?

The digitalization of the process industry is advancing rapidly — and with it, Ethernet-APL is becoming increasingly important. Especially in hazardous areas up to Zone 0, one key question arises: How can modern communication technology be implemented safely and efficiently? This is exactly where the 2-WISE concept comes into play.

In process automation, many operators rely on the type of protection known as “Intrinsic Safety.” It allows systems to be maintained and expanded even during operation — a clear advantage in everyday plant operation.

However, the traditional approach, the so-called “Entity Model,” involves considerable effort. Every device, every barrier stage, and every cable must be precisely matched to one another. As a result, the mandatory verification of intrinsic safety often requires complex calculations, detailed documentation, and significant engineering effort.

With the introduction of fieldbus systems, this issue was already addressed to some extent — but with Ethernet-based systems, the complexity threatened to increase again.

2-WISE (2-Wire Intrinsically Safe Ethernet) was developed as a concept that combines the benefits of intrinsic safety with the simplicity of standardized systems. Similar to the well-known FISCO model, 2-WISE defines fixed parameters for devices, cables, and system architecture.

In practical terms, this means:

• Uniform safety parameters for all components
• Standardized cables (e.g., Type-A fieldbus cable)
• Defined limits for cable lengths and number of devices
• No complex intrinsic safety calculations required

Instead of extensive verification procedures, it is sufficient to ensure that all installed components are 2-WISE certified and properly marked. Only the 2-WISE interconnections need to be documented within the explosion protection documentation.

One major advantage of 2-WISE is the significant simplification of planning and installation. Defined power classes additionally specify the maximum energy available for a field device:

• Power Class A: 0.54 W (ia)
• Power Class B: 1.17 W (ia)
• Power Class C: 1.11 W (ic)

This structure not only simplifies system design but also enables larger networks and seamless IP communication all the way to the field level.

2-WISE is intentionally based on the familiar FISCO parameters. This greatly simplifies the migration of existing fieldbus installations toward Ethernet-APL. Many field switches support both FISCO and 2-WISE — a clear advantage for brownfield installations.

One important point: only systems that are fully 2-WISE compliant meet the requirements for intrinsically safe Ethernet-APL installations in hazardous areas. Applications that do not require intrinsic safety are addressed more efficiently using Single Pair Ethernet (SPE) technology.

2-WISE is a key building block for the safe and practical use of Ethernet-APL in the process industry. It significantly reduces the complexity of intrinsic safety, simplifies engineering, and at the same time provides the foundation for powerful, future-proof networks. This makes one thing clear: anyone looking to implement Ethernet-APL in hazardous areas cannot avoid 2-WISE.