Current Transformers: specification errors and solutions

After a reminder of current transformers (CTs), the author highlights the errors most often encountered when defining current transformers, an essential and little known link between the electrical network and the protection relays. It explains how to find a way out of difficult situations: CTs that cannot be manufactured, delays, additional costs, malfunctions, etc. This "Cahier Technique" should be useful for electricians designing installations, for protection specialists, panel builders and all CT manufacturers. It is in the best interest of all to exchange all information required for the safety and optimisation of CTs. This Cahier Technique is an operational addition to Cahier Technique no.194 “Current Transformers: how to specify them”.