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PIS-CS-032/Measurement

Testing beyond the grid's influence zone

The auxiliary probes were inside the system they were supposed to measure from outside.

Interconnected systemsEnergy3 min read
Move auxiliary probes beyond grid influenceEngineered approach for PIS-CS-032. Base separation on grid dimensions and actual site constraints. Extend current and potential probe arrangements appropriately. Validate the curve and repeat direction where site conditions require. Conceptual teaching detail, not an as-built drawing or construction instruction. © PIS Engineering Academy · All rights reserved.PIS ENGINEERING / CASE 032Move auxiliary probes beyond grid influenceENGINEERED APPROACHPCCURVE TESTEARTH TESTEREPCVERIFY REMOTE REFERENCEIllustrative curve only; derive the method and distances from the actualgrid.1231Base separation on griddimensions and actual siteconstraints.2Extend current and potentialprobe arrangementsappropriately.3Validate the curve and repeatdirection where siteconditions require.READ THE DETAILEquipment, joints and current-path interfaces are shown in context.Conceptual teaching plate · no project dimensions or acceptance limits impliedPIS / REV 03© PIS Engineering Academy · All rights reserved

Engineering concept / vector field note

01

The field problem

Interconnected Grounding Systems

Final resistance testing placed current and potential probes within the station/grid influence area.

why the obvious answer can be misleading

The injected test current did not reach a sufficiently remote reference, so the measured voltage gradient was contaminated by the grid’s own influence.

02

Why it failed

The injected test current did not reach a sufficiently remote reference, so the measured voltage gradient was contaminated by the grid’s own influence.

03

Follow the engineering

Switch between the field condition and the engineering concept. Trace the path and examine what changes.

Inspect the engineering detail

Move auxiliary probes beyond grid influenceEngineered approach for PIS-CS-032. Base separation on grid dimensions and actual site constraints. Extend current and potential probe arrangements appropriately. Validate the curve and repeat direction where site conditions require. Conceptual teaching detail, not an as-built drawing or construction instruction. © PIS Engineering Academy · All rights reserved.PIS ENGINEERING / CASE 032Move auxiliary probes beyond grid influenceENGINEERED APPROACHPCCURVE TESTEARTH TESTEREPCVERIFY REMOTE REFERENCEIllustrative curve only; derive the method and distances from the actualgrid.1231Base separation on griddimensions and actual siteconstraints.2Extend current and potentialprobe arrangementsappropriately.3Validate the curve and repeatdirection where siteconditions require.READ THE DETAILEquipment, joints and current-path interfaces are shown in context.Conceptual teaching plate · no project dimensions or acceptance limits impliedPIS / REV 03© PIS Engineering Academy · All rights reserved

Case 032 · Engineered approach

100%
Move auxiliary probes beyond grid influenceEngineered approach for PIS-CS-032. Base separation on grid dimensions and actual site constraints. Extend current and potential probe arrangements appropriately. Validate the curve and repeat direction where site conditions require. Conceptual teaching detail, not an as-built drawing or construction instruction. © PIS Engineering Academy · All rights reserved.PIS ENGINEERING / CASE 032Move auxiliary probes beyond grid influenceENGINEERED APPROACHPCCURVE TESTEARTH TESTEREPCVERIFY REMOTE REFERENCEIllustrative curve only; derive the method and distances from the actualgrid.1231Base separation on griddimensions and actual siteconstraints.2Extend current and potentialprobe arrangementsappropriately.3Validate the curve and repeatdirection where siteconditions require.READ THE DETAILEquipment, joints and current-path interfaces are shown in context.Conceptual teaching plate · no project dimensions or acceptance limits impliedPIS / REV 03© PIS Engineering Academy · All rights reserved

Scroll to inspect. Numbered details match the notes below the drawing. Conceptual geometry; use the case text for the engineering requirements.

What changes

Base current-probe distance on grid dimensions and site constraints, extend beyond the influence zone, and validate potential-probe location using an appropriate curve/slope approach.

Teaching schematic · not to scale© PIS Engineering Academy · All rights reserved
04

Correction & verification

Base current-probe distance on grid dimensions and site constraints, extend beyond the influence zone, and validate potential-probe location using an appropriate curve/slope approach.

Verification recorded in the case

  • Repeat in more than one direction where site geometry or buried services make the result uncertain.
  • Record as-built topology and connection points.
  • Repeat the measurement or functional test under a defined condition.
  • Confirm continuity and mechanical integrity of the corrected path.
  • Document instrument/setup, environmental condition and test method.
  • Close the NCR/case only when evidence supports the conclusion.
References & project context

References are reproduced from the PIS casebook. Select the governing edition and project acceptance criteria before using them for a design. The diagrams explain the concept, rather than define construction dimensions.

Large-grid measurement practice; IEC 61557-5 principles.

PIS reviewed field handbook · PIS-CS-032

View the original social card
05

The engineering lesson

Remote earth must actually be remote relative to the grid under test.

Take the lesson into your next design review.

Keep exploring

Connected lessons.

All cases
Solar trackers, geology and the measurement objectiveEngineered approach for PIS-CS-006. Profile soil depth and select electrode arrangements from evidence. Use the test method appropriate to isolated or interconnected topology. Verify tracker bonding and correlate measurements with control behaviour. Conceptual teaching detail, not an as-built drawing or construction instruction. © PIS Engineering Academy · All rights reserved.PIS ENGINEERING / CASE 006Solar trackers, geology and the measurement objectiveENGINEERED APPROACHTRACKERARRAY STRUCTURE / TRACKER DRIVE / CONTROL INTERFACESSoil model, test topology and control behaviour are separate checks.1231Profile soil depth and selectelectrode arrangements fromevidence.2Use the test methodappropriate to isolated orinterconnected topology.3Verify tracker bonding andcorrelate measurements withcontrol behaviour.READ THE DETAILEquipment, joints and current-path interfaces are shown in context.Conceptual teaching plate · no project dimensions or acceptance limits impliedPIS / REV 03© PIS Engineering Academy · All rights reserved
06

Measurement

Solar earthing & tracker control

One test method cannot describe every part of a solar plant.

Benban, Aswan3 min
Read a curve, not one assumed probe positionEngineered approach for PIS-CS-031. Extend and document the test line for the actual grid. Plot multiple probe positions; use the justified curve/slope method. Derive and verify the result without assuming a universal position. Conceptual teaching detail, not an as-built drawing or construction instruction. © PIS Engineering Academy · All rights reserved.PIS ENGINEERING / CASE 031Read a curve, not one assumed probe positionENGINEERED APPROACHPCCURVE TESTEARTH TESTEREPCMULTIPLE PROBE POSITIONSIllustrative curve only; derive the method and distances from the actualgrid.1231Extend and document the testline for the actual grid.2Plot multiple probepositions; use the justifiedcurve/slope method.3Derive and verify the resultwithout assuming a universalposition.READ THE DETAILEquipment, joints and current-path interfaces are shown in context.Conceptual teaching plate · no project dimensions or acceptance limits impliedPIS / REV 03© PIS Engineering Academy · All rights reserved
31

Measurement

A large grid cannot be tested like a rod

A large grid cannot be tested like a small rod.

Benban Solar Park3 min
Survey zone, installed soil and electrode interactionEngineered approach for PIS-CS-001. Characterise the actual soil around the installed electrodes. Coordinate spacing using the site soil model and electrode geometry. Validate probe geometry and repeatability before accepting the reading. Conceptual teaching detail, not an as-built drawing or construction instruction. © PIS Engineering Academy · All rights reserved.PIS ENGINEERING / CASE 001Survey zone, installed soil and electrode interactionENGINEERED APPROACHSURVEYED SOILBACKFILLED INSTALLATIONSOIL SURVEYSOIL RESISTIVITYC1P1P2C2COORDINATED SPACINGSoil changes across the site. Rods interact below ground.1231Characterise the actual soilaround the installedelectrodes.2Coordinate spacing using thesite soil model and electrodegeometry.3Validate probe geometry andrepeatability beforeaccepting the reading.READ THE DETAILEquipment, joints and current-path interfaces are shown in context.Conceptual teaching plate · no project dimensions or acceptance limits impliedPIS / REV 03© PIS Engineering Academy · All rights reserved
01

Measurement

Soil resistivity & rod spacing

Never Trust One Soil Resistivity Test.

New Cairo3 min
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