Users must select and install equipment in such a way as to limit HF interference as much as possible. State-of-the-art protection systems are available.
These consist of:
Electronic variable speed drives are widely used in the industrial and Ex sectors. They offer many advantages for motor users:
- high efficiency and reliability
- precise steering
- flexible use for all requirements
- optimised engine service life
Variable speed drives use electronic switches (diodes, thyristors, IGBT transistors, etc.) to vary the frequency of the engine’s power supply, thereby controlling its speed.
The switch action generates harmful electromagnetic pollution which is conducted and radiated throughout the installation. This pollution consists of:
- current/voltage harmonics
- high-frequency (HF) interference, generally between 2 and 16 kHz. It can cause equipment failure due to overloads or loss of operation due to unexpected tripping of protection systems
To offset these risks, variable speed drive manufacturers use filters to eliminate the harmonics created.
To meet these requirements, MARECHAL ELECTRIC has developed a passive, high-performance solution that is easy to install and consists in selecting:
metal-clad appliances
metal accessories
(handle, box, sleeve, socket)cable glands (PE) with suitable screening, supplied by MARECHAL ELECTRIC
The EMC performance of MARECHAL® appliances was measured by the Laboratoire National d’Essai (LNE – France) in 2022. The tests carried out are based on the requirements of standard ISO 11452-4, and involve measuring the transmission efficiency of the current/signal passing through MARECHAL® appliances, for frequencies ranging from: – 0 Hz to 20 kHz (range of disturbances generated by variable speed drives): the losses measured are negligible (identified in red on the graph), – 20 kHz to 500,000 kHz: measured losses fluctuate between -2 dB and -33 dB. The MARECHAL® solution is perfectly suited to applications implementing variable speed drives.