The electromagnetic compatibility describes – according to the definition of the EMC directive – the "capability of a device to work satisfactorily in an electromagnetic environment without itself causing electromagnetic interference which is unacceptable for other devices present in this environment". To guarantee that the appropriate EMC standards are observed, the devices must demonstrate a sufficiently high noise immunity, and also the emitted interference must be limited to acceptable values.

Product standard EN 61800‑3 describes the EMC requirements placed on "Variable-speed drive systems".

A variable-speed drive system (or Power Drive System PDS) consists of the Control Unit and Power Module or Control Unit, Line Module and Motor Module plus the relevant electric motors and encoders including connecting cables.

The driven machine is not part of the drive system.

Environments

EN 61800‑3 defines different requirements depending on the location where the drive is installed, designated as a first and second environment. Residential buildings or locations where the drive system is directly connected to a public low-voltage supply without intermediate transformer are defined
as the first environment. All locations outside a residential area are defined
as the second environment. These are basically industrial areas which are supplied from the medium-voltage network via their own transformers.

Categories

Four different categories are defined in EN 61800‑3 depending on the installation site of the drive:

Category C1: Drive systems for rated voltages < 1000 V for unlimited use in the first environment.

Category C2: Stationary drive systems for rated voltages < 1000 V for use in the second environment. Use in the first environment is possible if the drive system is operated and installed by qualified personnel. The warning information and installation instructions supplied by the manufacturer must be observed.

Category C3: Drive systems for rated voltages < 1000 V for exclusive use in the second environment.

Category C4: Drive systems for rated voltages ≥ 1000 V, for rated currents ≥ 400 A or IT supply systems for use in complex systems in the second environment. An EMC plan must be drawn up.