Most Inverter Drives have a insignificant leakage path to earth via the filtering capacitors. This is a not an issue for an installation with a secure earth. Most Inverters have dual provision for earth connections to ensure the protective earth is secure.
Where an installation has an RCD (ELCB) Earth Leakage trip for personnel protection. The leakage before tripping is usually permanently set around 30mA. The leakage through the Inverter EMC filters varies from around 20mA upwards, depending on the type of filter (Industrial or Domestic) and the size of the inverter.
There are different types of earth leakage trip, their characteristics and suitability for use with Inverter Drives varies as follows:-
There are three common types of RCD (ELCB):-
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Type A - Detects AC and pulsating DC fault currents, provided the DC current reaches zero at least once every half cycle - This type can only be used with single phase drives.
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Type B - Detects AC, pulsating DC and smooth DC fault currents - This type must be used with three phase drives.
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Type AC - Detects AC fault currents only - This type should never be used with Inverter drives.