MediaWiki:Eig-ch-menu-G

Chapter G

Sizing and protection of conductors

• Conductor sizing and protection
  • Conductor sizing: methodology and definition
  • Overcurrent protection principles
  • Practical values for a protective scheme
  • Location of protective devices
  • Conductors in parallel
• Practical method for determining the smallest allowable cross-sectional area of circuit conductors
  • General method for cable sizing
  • Recommended simplified approach for cable sizing
  • Sizing of busbar trunking systems (busways)
• Determination of voltage drop
  • Maximum voltage drop limit
  • Calculation of voltage drop in steady load conditions
• Short-circuit current
  • Short-circuit current at the secondary terminals of a MV/LV distribution transformer
  • 3-phase short-circuit current (Isc) at any point within a LV installation
  • Isc at the receiving end of a feeder as a function of the Isc at its sending end
  • Short-circuit current supplied by a generator or an inverter
• Particular cases of short-circuit current
  • Calculation of minimum levels of short-circuit current
  • Verification of the withstand capabilities of cables under short-circuit conditions
• Protective earthing conductor (PE)
  • Connection and choice for protective earthing conductor
  • Sizing of protective earthing conductor
  • Protective conductor between MV/LV transformer and the Main Low Voltage Switchboard (MLVS)
  • Equipotential conductor
• The neutral conductor
  • Sizing the neutral conductor
  • Protection of the neutral conductor
  • Breaking of the neutral conductor
  • Isolation of the neutral conductor
• Worked example of cable calculation

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