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ReferenceReading orders

Reading orders

Earth mat design

The topics of the Earthing step, from the soil's resistivity to the mesh and step voltages of the mat.

  1. 1Soil resistivity and Wenner readingsHow the soil's resistivity is measured by the Wenner method of IS 3043:1987, and the value the earth mat's design takes from the readings.
  2. 2Two-layer soilThe two-layer soil model fitted to Wenner readings that vary with spacing, and how the earth mat's design uses its layers.
  3. 3Tolerable body currentThe body current a person tolerates for the duration of a shock, by IEEE Std 80-2013 §5.3, and the tolerable touch and step voltages it sets.
  4. 4Surface layer and CsThe layer of crushed rock over the earth mat, and its derating factor Cs by IEEE Std 80-2013 §7.4, which raise the tolerable touch and step voltages.
  5. 5Conductor sizingThe cross-section an earth mat's conductor needs to carry the fault current without exceeding its temperature limit, by IEEE Std 80-2013 §11.3.1.
  6. 6Grid currentThe share of an earth fault's current that flows from the earth mat into the soil, with its DC offset, by IEEE Std 80-2013 §15.
  7. 7Grid resistance and GPRThe earth mat's resistance to remote earth by IEEE Std 80-2013 §14.2, and the rise of earth potential it gives with the grid current.
  8. 8Mesh voltage and touch voltageThe touch voltage a person meets inside a mesh of the earth mat, the mesh voltage of IEEE Std 80-2013 §16.5.1, and how the mesh spacing changes it.
  9. 9Step voltageThe tolerable step voltage from the body's circuit, and the step voltage of an earth mat by the IEEE 80-2013 equations.
  10. 10Earth mat analysis in two-layer soilThe numerical analysis of the earth mat in a two-layer soil: the mat as segments, their currents, the grid resistance and the surface voltages.

Short-circuit study

The topics of the Short circuit step, from the network's impedances to the switchgear rating checks.

  1. 1Short-circuit currents by IEC 60909-0The initial symmetrical short-circuit currents at the HV and MV buses by the equivalent voltage source of IEC 60909-0:2016, maximum and minimum.
  2. 2Peak current and thermal equivalent currentThe peak factor κ by method B, the peak short-circuit current ip, the thermal equivalent current Ith by IEC 60909-0:2016, and the switchgear rating checks.
  3. 3Short-circuit duty by IEEE C37.010The circuit breaker duty of the ANSI / IEEE set by the E/X method of IEEE C37.010-2016: X/R ratio, duty factor, closing and latching, against IEEE C37.04-2018.
  4. 4Bus and bay current ratingsThe HV bus and bay rated currents per voltage level, and the MV incomer and bus rating from the transformer's low-voltage current.

Insulation and clearances

The topics of the insulation levels and the yard clearances that the Yard layout step checks.

  1. 1Insulation levelsThe highest system voltage, the impulse withstand voltages and the surge arrester rating the design takes per voltage level.
  2. 2Electrical clearancesPhase-to-earth, phase-to-phase, sectional and ground clearances of the IEC + CEA / CBIP set per voltage level, and their correction for altitude.
  3. 3Clearances of the ANSI / IEEE setYard clearances by RUS Bulletin 1724E-300 Table 4-7, the NESC 2007 live-part and fence clearances, and the higher BIL row for altitude.

Lightning protection

The topics of the Lightning protection step, from the rolling sphere's radius to the coverage of the masts and shield wires.

  1. 1Direct stroke shielding by the rolling sphereThe rolling sphere radius per protected level by the revised electrogeometric model of IEEE Std 998-2012, and the IEC 62305-3 sphere.
  2. 2Masts and shield wiresHow the design places shield wires over the HV yard and lightning masts elsewhere, and checks the protected levels by the rolling sphere.

Single-line diagram

The topics of the Single-line diagram step, from the drawing's conventions to the bays and their ratings.

  1. 1Single-line diagram (SLD)The single-line diagram of a pooling substation: what it shows, the order of the equipment in a bay, and the ratings it carries.
  2. 2Graphical symbolsThe symbols of the single-line diagram, simplified from IEC 60617, and the devices they stand for.
  3. 3Bus schemesHow the circuits of a high-voltage substation connect to its buses: double main bus, one-and-a-half breaker, single sectionalised bus, single bus and ring bus.
  4. 4Bays and their equipmentThe bays of a high-voltage switchyard (line, transformer, coupler, bus section and future bays) and the equipment each one carries in order.
  5. 5Bus and bay current ratingsThe HV bus and bay rated currents per voltage level, and the MV incomer and bus rating from the transformer's low-voltage current.

Yard layout

The topics of the Yard layout step, from the bus scheme and the bays to the clearances the yard keeps.

  1. 1Bus schemesHow the circuits of a high-voltage substation connect to its buses: double main bus, one-and-a-half breaker, single sectionalised bus, single bus and ring bus.
  2. 2Bays and their equipmentThe bays of a high-voltage switchyard (line, transformer, coupler, bus section and future bays) and the equipment each one carries in order.
  3. 3Electrical clearancesPhase-to-earth, phase-to-phase, sectional and ground clearances of the IEC + CEA / CBIP set per voltage level, and their correction for altitude.
  4. 4Clearances of the ANSI / IEEE setYard clearances by RUS Bulletin 1724E-300 Table 4-7, the NESC 2007 live-part and fence clearances, and the higher BIL row for altitude.