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Type B RCDs

M. Joshi
Increasingly, I am seeing a requirement for Type B RCDs in industrial applications, particularly where servo drives are used.


The preference is Type B RCBOs however, these are quite rare and not all manufacturers make them.


Aside from the high cost and short supply due to demand from EV and PV applications, how do others address this situation?


If the earthing is adequate, cables to the motors are run in trays and there is additional bonding to the motor housing, is there really a need for an RCD?
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    Thanks for the replies.  The manufacturer of the servo drives recommend a Type B RCD however, the UK distributor usually don't use them in their installs or advise their customers to either. Instead, they recommend additional earth braid bonding to the motor housing.


    The supply is I believe TNs.


    Although the manufacturer have said to follow the UK distrubutor's advice in other areas where electrical specifications may be intended for other countries, I am erring on the side of caution and using 30mA Type B RCCBs (together with C Curve MCBs) in line with the manufacturer's recommendation.  This usually seems to be the best approach where finger pointing will ensue if an incident were to occur!


    Based on test data, typically the servo drive may have a DC leakage of around 10mA.


    With two servo drives per RCCB, I'm hoping that the leakage current won't be too high?


    Unfortunately, availability of Type B RCDs is difficult at the moment as mentioned above and also due to the global component shortages.


    It'd be interesting to know how others address similar requirements at present?

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  • 0
    Thanks for the replies.  The manufacturer of the servo drives recommend a Type B RCD however, the UK distributor usually don't use them in their installs or advise their customers to either. Instead, they recommend additional earth braid bonding to the motor housing.


    The supply is I believe TNs.


    Although the manufacturer have said to follow the UK distrubutor's advice in other areas where electrical specifications may be intended for other countries, I am erring on the side of caution and using 30mA Type B RCCBs (together with C Curve MCBs) in line with the manufacturer's recommendation.  This usually seems to be the best approach where finger pointing will ensue if an incident were to occur!


    Based on test data, typically the servo drive may have a DC leakage of around 10mA.


    With two servo drives per RCCB, I'm hoping that the leakage current won't be too high?


    Unfortunately, availability of Type B RCDs is difficult at the moment as mentioned above and also due to the global component shortages.


    It'd be interesting to know how others address similar requirements at present?

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