Know How: Electrical General

Calculation of short-circuit currents


In view of sizing an electrical installation and the required equipment, as well as determining the means required for the protection of life and property, short-circuit currents must be calculated for every point in the network.
This “Cahier Technique” reviews the calculation methods for short-circuit currents as laid down by standards such as IEC 60909. It is intended for radial and meshed low-voltage (LV) and high-voltage (HV) circuits.
The aim is to provide a further understanding of the calculation methods, essential when determining short-circuit currents, even when computerised methods are employed.


  • - Author :B. de Metz-Noblat, F. Dumas, C. Poulain
  • - Publication date:01/09/2005
  • - Page number:32
  • - ECT no:158

Power Quality


One of the properties of electricity is that some of its characteristics depend not only on the electricity producer/distributor but also on the equipment manufacturers and the customer. The large number of players combined with the use of terminology and definitions which may sometimes be
imprecise partly explain why this subject area is so complex.
This "Cahier Technique" aims to facilitate exchanges on this topic between specialists and non-specialists, as well as customers, manufacturers, installers, designers and distributors. The clear terminology used should help avoid confusion. It describes the main phenomena causing degradation in Power Quality (PQ), their origins, the consequences for equipment and the main solutions. It offers a methodology for measuring the PQ in accordance with differing aims. Illustrated with practical examples for the implementation of solutions, it shows that only by observing best practice and by applying strict methodology (diagnostics, research,solutions,implementation and preventive maintenance) can users obtain the right quality of power supply for their requirements.


  • - Author :Philippe FERRACCI
  • - Publication date:01/10/2001
  • - Page number:36
  • - ECT no:199

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