Electromagnetic compatibility is a discipline, which is involved in securing maximum reliability of each electrical and electronic equipment and devices. In nature, there are relations between elements or system components, which must be predicted in advance in order to prevent interference.
Electromagnetic compatibility seems to be a relatively new discipline, which arose in the sixties in the USA. It started on basis of the necessity to secure flawless and reliable activity of electrotechnical equipment and devices working especially in military or aerospace systems.
Electromagnetic compatibility begins to affect all of us by the development of electronics, especially microprocessor technique, which effect our day to day lives. That is why EU issued the directive No. 89/336/EEC, whose aim is to enforce electromagnetic compatibility conditions on all states involved including the states that have signed associate agreement.
The Czech Republic has also signed this agreement so all the conditions of the directive apply. Of course it is necessary that the Czech Republic would gradually have made appropriate legislative steps, which would turn this directive to live. The decree of the Czech goverment No. 17/2003 and the law No. 22/97 Coll. means nonreplaceable move in this sphere.
Other very important decrees concerning this sphere are obligatory norms as for example CSN 332000-1, paragraph 131.6.2 saying:
„People, lifestock and also property must be protected against harm caused by surge, which can arise from other reasons, for example atmospheric events, switching overvoltages and static electric.“
At the figure there are particular links among electrical equipment and enviroment shown. They can be expressed as two relations:
– electromagnetic susceptibility (resistance)
– electromagnetic interference (disturbance)
Surge is just one of the main problems arising from the solving of electromagnetic compatibility problems.
If we deal with parameters of electric energy, we must remember four qualitative aspects:
– the level of voltage- the level of frequency
– nonlinear distortion
– the level of surge (frequency of surge peaks)
On basis of these aspects the electric energy can be taken as merchandise and these qualitative parameters can be required. The main aim is to create such conditions that would be able to ensure maximum reliability and functioning of all the electronic equipment connected to LV power systems.