An AC earth leakage protection circuit breaker can be positioned on the upstream side of a drive, provided the current on the drive do not exceed the current rated for RCCB available.

• With single-phase power supply : all ATV11 and ATV12 ratings and some ATV31, ATV312, ATV61 and ATV71 ratings
• With three-phase power supply but rating lower than 50 kW (ATV31, ATV312, ATV61 and ATV71)

These drives have RFI filters to reduce radio interference.
The secondary effect of this RFI filter is the generation of a DC component that can be detected by the AC circuit breaker as an earth leakage.
Disconnecting the filter from the drive solves the breaking problem but does not solve the problem of radio interference.
To maintain the radio interference reduction effect of the RFI filter while making the installation available (no more breaking) type A SI (super immunized) or type B circuit breakers or RCCBs must be used.

The various types of earth leakage protection

For low rating (less than 50 kW) drives with three-phase power supply, the best solution therefore seems to be type B RCCBs:

For all drives (rating less than 50 kW), it is possible to use type A circuit breakers with earth leakage protection.

The long motor cable length can also create high levels of earth current due to stray capacitance on the output of the variable speed drives.
For extra information refer to the attachment.

Released for:Schneider Electric UK