Magnetic field density analysis in switchgears

For many years the evaluation of the electromagnetic field (EMF) generated by transformer substations (TS) and switchgear assemblies has been an extremely cumbersome and expensive process. Manufacturers and users of TS and switchgear lacked a broadly-accepted assessment procedure specified in an international reference standard. The publication of the new Technical Report IEC/TR 62271-208 solves this situation since it describes a technique for the evaluation of the EMF generated by switchgear assemblies and TS and opens the possibility of employing simulation tools for this purpose. In this paper, preliminary stage of process for validation of simulation tests in order to substitute laboratory tests according to IEC/TR 62271-208, is described. With this purpose, magnetic field emission analysis is carried out using finite elements (FE) method, for a set of 5 identical switchgears (manufactured by Ormazabal), in series connection. Results obtained through simulation are compared to those measured in laboratory tests. Evaluation results are also compared with applicable limits (100 µT and 500 µT at 50 Hz, according to most human exposure regulations: ICNIRP Guidelines, EU Council Recommendation, Spanish Royal Decree 1066/2001, etc).