Topological Protection Requirements

Published on Dec 8, 2025 Last updated on Dec 10, 2025 5 min read Under Review

Change History

IdSubjectDate
Latest CommitAdded guideline for topology zones (#1138)2025-12-10
Routing Variants in the VEC2025-12-08

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This page or section resolves #1138

Background

During geometrical harness design (e.g. in 3D), certain sections of the electrical wiring harness may require additional protection — e.g., increased abrasion resistance or sound damping — due to the local mechanical or environmental conditions at the vehicle.

Modelling Options

In the VEC, there are two relevant modeling approaches to express such requirements or solutions:

  1. Using a PartUsage to define Requirements for a wire protection component.
  2. Using a TopologyZone to describe conditions and requirements implied by topology elements

This guideline explains when to use which approach and clarifies the validity of zones covering disjoint locations.

PartUsage

A PartUsage represents a placeholder component that must later be realized as a PartOccurrence during detailed design and production preparation. The PartOrUsageRelatedSpecification referenced by the PartUsage express requirements for a wire protection component, that must be satisfied by the PartOccurrence selected later in the process,without defining the actual solution or specific component.

Use this approach when:

  • You are already defining the solution for a requirement
  • It is known what type of protection will be installed (e.g. tape, tube, sleeve…)
  • Placement along segments is already planned
  • Properties of the planned protection need to be specified (e.g. SoundDampingClass, RobustnessProperties, Material etc.)

Statement expressed:
“A wire protection component will be installed here, and here are its intended characteristics.”

TopologyZone

A TopologyZone represents a spatial condition in the vehicle that imposes requirements on the harness.

Use this approach when:

  • You want to express requirements caused by the installation environment
  • No specific solution has yet been decided
  • The affected topology areas may be intermittent (segments enter or exit the zone)

Examples:

  • “Wet zone close to the ground”
  • “High-abrasion zone at specific contact points”
  • Areas requiring sound damping due to vibration risk

Statement expressed:
“Segments inside this zone must satisfy certain robustness or damping requirements.”

Topology Zone Example

The following section explains how TopologyZones work using a specific example. A description of the general concepts of topology zone modelling in the VEC can be in found in Specification, Chapter “Topology Zones”.

The figure below shows a TopologySegment routed through different topology zones in a vehicle. Each zone represents an area with specific environmental conditions that impose requirements on the wiring harness. In this example a Hot Zone (red) and a Wet Zone (blue) are defined. The example topology consists of three segments:

  • SEG-I: Starts at ND-I in no specific zone, then enters the Hot Zone at the location Loc A and ends at ND-IV, still in the Hot Zone.
  • SEG-II: Starts at ND-IV in the Hot Zone and ends at ND-II in no specific zone. It leaves the Hot Zone at Loc B. On its way it passes through the Wet Zone between locations Loc C and Loc D. Between Loc C and Loc B the segment is therefore in both zones simultaneously.
  • SEG-III: Located entirely within the Hot Zone.
Topology Zones
Topology Zones

The assignments of the segments to the zones are modelled using ZoneAssignments. Each assignment defines the relation between a TopologySegment and a TopologyZone. If the TopologySegment is only partially located within the TopologyZone a ZoneCoverage defines the start and end locations of the coverage on the segment. Multiple ZoneCoverages can be defined for one ZoneAssignment to cover disjoint areas of a segment.

The zones are defined solely on the basis of the topology, which is ‘formless’ in the VEC. The spatial characteristics and shape of the topology zones are also not part of the VEC. The modelling of the topology zones and determining the corresponding intersections with the topology is the task of an engineering system. The topology zones in the VEC represent the result of this process.

The XML snippets in the following sections are taken from a consistent file representing the example above. For better readbability, some part of the XML are omitted. This is indicated by using ... in the XML. The complete VEC file can be downloaded from the Additional Resources at the end of this page.

The definition consists of two relevant specifications: A TopologySpecification and TopologyZoneSpecification for the zones. In this example, both are contained in the same DocumentVersion. The definition of the topology looks as follows:

    ...
    <Specification xsi:type="vec:TopologySpecification" id="TopologySpecification_00002">
      <Identification>TOPOLOGY</Identification>
      <TopologyNode id="TopologyNode_00003">
        <Identification>ND-I</Identification>
      </TopologyNode>
      <TopologyNode id="TopologyNode_00004">
        <Identification>ND-II</Identification>
      </TopologyNode>
      <TopologyNode id="TopologyNode_00005">
        <Identification>ND-III</Identification>
      </TopologyNode>
      <TopologyNode id="TopologyNode_00006">
        <Identification>ND-IV</Identification>
      </TopologyNode>
      <TopologySegment id="TopologySegment_00007">
        <Identification>SEG-I</Identification>
        <EndNode>TopologyNode_00006</EndNode>
        <StartNode>TopologyNode_00003</StartNode>
        <LengthInformation id="SegmentLength_00008">
          <Length id="NumericalValue_00009">
            <UnitComponent>SIUnit_00037</UnitComponent>
            <ValueComponent>1100.0</ValueComponent>
          </Length>
          <Classification>Designed</Classification>
        </LengthInformation>
      </TopologySegment>
      <TopologySegment id="TopologySegment_00010">
        <Identification>SEG-II</Identification>
        <EndNode>TopologyNode_00004</EndNode>
        <StartNode>TopologyNode_00006</StartNode>
        ...
      </TopologySegment>
      <TopologySegment id="TopologySegment_00013">
        <Identification>SEG-III</Identification>
        <EndNode>TopologyNode_00006</EndNode>
        <StartNode>TopologyNode_00005</StartNode>
        ...
      </TopologySegment>
    </Specification>
    ...

The definition of the Zones is the following. The snippet shows the complete definition of the Hot Zone. The definition of the Wet Zone is similar and therefore the assigment section is omitted here (see complete file for a full reference).

For SEG-I and SEG-II the assignment defines a ZoneCoverage to indicate the start and end locations of the coverage on the segment, since they are only partially within in the zone. If those segments had multiple areas where the interacted with zone, each area would be defined by an indiviual ZoneCoverage. SEG-III is entirely within the Hot Zone and therefore does not need a coverage definition.

    ...
    <Specification xsi:type="vec:TopologyZoneSpecification" id="TopologyZoneSpecification_00016">
      <Identification>TOPOLOGY-ZONES</Identification>
      <Zone id="TopologyZone_00017">
        <Identification>HOT</Identification>
        <AmbientTemperature id="TemperatureInformation_00018">
          <TemperatureRange id="ValueRange_00019">
            <UnitComponent>SIUnit_00041</UnitComponent>
            <Minimum>-30.0</Minimum>
            <Maximum>125.0</Maximum>
          </TemperatureRange>
          <TemperatureType>AmbientTemperature</TemperatureType>
        </AmbientTemperature>
        <!-- SEG-I is partially within the Hot Zone, from Loc A to ND-IV -->
        <Assignment id="ZoneAssignment_00018">
          <AssignedSegment>TopologySegment_00007</AssignedSegment>
          <Coverage id="ZoneCoverage_00019">
            <FirstLocation xsi:type="vec:NodeLocation" id="NodeLocation_00020">
              <Identification>ND-IV</Identification>
              <ReferencedNode>TopologyNode_00006</ReferencedNode>
            </FirstLocation>
            <SecondLocation xsi:type="vec:SegmentLocation" id="SegmentLocation_00021">
              <Identification>Loc A</Identification>
              <Offset id="NumericalValue_00022">
                <UnitComponent>SIUnit_00037</UnitComponent>
                <ValueComponent>600.0</ValueComponent>
              </Offset>
              <Anchor>FromEndNode</Anchor>
              <ReferencedSegment>TopologySegment_00007</ReferencedSegment>
            </SecondLocation>
          </Coverage>
        </Assignment>
        <!-- SEG-II is partially within the Hot Zone, from ND-IV to Loc B -->
        <Assignment id="ZoneAssignment_00023">
          <AssignedSegment>TopologySegment_00010</AssignedSegment>          
          <Coverage id="ZoneCoverage_00024">
            <FirstLocation xsi:type="vec:NodeLocation" id="NodeLocation_00025">
              <Identification>ND-IV</Identification>
              <ReferencedNode>TopologyNode_00006</ReferencedNode>
            </FirstLocation>
            <SecondLocation xsi:type="vec:SegmentLocation" id="SegmentLocation_00026">
              <Identification>Loc B</Identification>
              <Offset id="NumericalValue_00027">
                <UnitComponent>SIUnit_00037</UnitComponent>
                <ValueComponent>500.0</ValueComponent>
              </Offset>
              <Anchor>FromStartNode</Anchor>
              <ReferencedSegment>TopologySegment_00010</ReferencedSegment>
            </SecondLocation>
          </Coverage>
        </Assignment>
        <!-- SEG-III is entirely within the Hot Zone -->
        <Assignment id="ZoneAssignment_00028">
          <AssignedSegment>TopologySegment_00013</AssignedSegment>
        </Assignment>
      </Zone>
       <Zone id="TopologyZone_00031">
        <Identification>WET</Identification>
        <RequiredRobustnessProperties id="RobustnessProperties_00032">
          <Class>LiquidIngressProtection</Class>
          <ClassKey>9K</ClassKey>
          <ClassReferenceSystem>ISO 20653</ClassReferenceSystem>
          <HasRobustness>true</HasRobustness>
        </RequiredRobustnessProperties>
        ...
      </Zone>
      ...
    </Specification>
    ...

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Last updated on Dec 10, 2025