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Why choose Type B RCD for 3 Phase Variable Speed Drives?

FAQ000184975

09 August 2021

For the 3 Phase Variable Speed Drives, the RCD type B or type B-Si is particularly suitable.
It protects against fault currents with DC offset, which is true for three-phase power converters. In addition, it has enhanced immunity against nuisance tripping caused by:

  • EMC common mode filters connected upstream VSD.
    Type B has a tripping delay allowing the inrush current to flow on power up.

  • The permanent switching leakage currents existing in power converters (ex: 25kHz).
    Type B include a "low pass" filter to ensure a trigger threshold which increases with frequency while complying with the personal protection curve (fibrillation).

Please note: if the required sensitivity is 300mA, Selective type RCD should be proposed ensuring a non-triggering time of 50ms. 

More information can be found on the Earth Fault Protection guide: https://download.schneider-electric.com/files?p_enDocType=Catalog&p_File_Name=CA908066E+%28web%29.pdf&p_Doc_Ref=CA908066E

With regards to installation of these RCDs, they are mounted upstream of the Variable Speed Drives.

See below example

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Schneider Electric offers Acti9 iID range of 4 Pole RCDs type B available in 30 mA sensitivity and type B-Si available in 30 and 300 mA sensitivity (Selective type is available)

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Click this link below to view the complete range of Acti9 iID RCDs available in Australia: https://www.se.com/au/en/product-range/7559-acti9-iid/?filter=business-5-residential-and-small-business&parent-subcategory-id=1620