Spur Isolation in Fieldbus Networks Using Segmented Transformers
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Solution Overview
Problem
Existing device couplers in two-wire process control networks fail to provide adequate galvanic isolation between the trunk and spur interfaces, allowing current to flow between spur interfaces and increasing the risk of electrical sparks and noise propagation, especially in hazardous locations.
Innovation Solution
A device coupler design where multiple spur interfaces are grouped into sets, each connected in parallel to a single isolation element, such as a transformer, ensuring galvanic isolation between sets and between each spur interface and the trunk interface, reducing the risk of electrical sparks and noise propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single transformer is used to isolate all spur interfaces from the trunk, then galvanic isolation between trunk and spurs is achieved, but current can flow between spur interfaces and they are not isolated from each other
Solution Approach 1:
The patent divides the spur interfaces into multiple isolation sets, where each set is connected to a separate isolation element (transformer). This segmentation ensures that current cannot flow between spur interfaces in different isolation sets, as they are electrically isolated by their respective transformers. The segmentation principle directly resolves the contradiction by creating electrical boundaries between spur interfaces while maintaining isolation from the trunk.
2Object-affected harmful factors
If multiple isolation elements are used to isolate each spur interface, then galvanic isolation between all spurs is achieved, but device complexity and cost increase
Solution Approach 1:
Instead of providing a separate isolation element for each individual spur interface, the patent segments spur interfaces into groups (isolation sets), with each set sharing a common isolation element. This reduces the total number of isolation elements required while still achieving galvanic isolation between all spur interfaces. For example, multiple spurs can share one transformer, reducing component count and complexity.
Solution Approach 2:
The patent combines multiple spur interfaces into isolation sets where they share a common isolation element. This merging approach reduces device complexity and cost by eliminating the need for separate isolation elements for each spur, while maintaining the essential function of galvanic isolation between spurs through the shared transformer.
3Device complexity
If spur interfaces are grouped into isolation sets with shared isolation elements, then device complexity is reduced, but isolation between spurs in the same set is compromised
Solution Approach 1:
The patent creates multiple isolation sets, where each set is electrically isolated from other sets by having its own dedicated isolation element. This segmentation ensures that spurs in different isolation sets maintain galvanic isolation, as current would need to pass through two separate transformers to flow between sets, which is effectively blocked. The segmentation principle resolves the contradiction by establishing electrical boundaries at the set level.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design effectively isolates spur interfaces from each other and the trunk, reducing the risk of electrical sparks and noise propagation, while minimizing costs by distributing the isolation elements among multiple spur interfaces, thus enhancing safety and reducing the need for additional safety barriers or specialized power supplies.
Implementation Method 1
An isolation element formed as a transformer 216 is connected to the trunk interface 212 and the spur interfaces 214. The transformer's primary winding 218 is connected to the trunk interface 212. The spur interfaces 214 are connected in parallel to the transformer's secondary winding 220. The transformer 216 provides isolation between the trunk interface 212 and all the spur interfaces 214
Data Source
AI summary
A method for providing galvanic isolation between an input or trunk interface (30) and multiple outputs or spur interfaces (38) for connecting field devices (14) to a trunk (20) of a two-wire (44a, 44b) process control network (10) includes connecting multiple sets of multiple spur interfaces to respective isolating elements (34). Each isolating element (34) connects a respective set of outputs or spur interfaces (38) to the trunk interface (30) and galvanically isolates (40, 42) the respective set of spur interfaces (38) from the trunk interface (30). Field devices (14) attached to different sets of spur interfaces are also galvanically isolated from one another.