Reg 419.2 Applicable to VSD driven motor?

Good afternoon,

When using cable design software such as ElectricalOM, there is a check box within the "Earthing" tab / adiabatic check of CPC. It states Provision of  regs 419.2 & 419.3 are applicable. (BS7671)

If checked it will remove the warning regarding the earth fault / disconnection time (should a warning exist with the modelled install)

Can someone confirm with a degree of certainty that the checkbox would reg 419.2 be applicable to a motor supplied from a VSD drive? 

Parents
  • So why would you consider a UPS part of fixed install and not VSD inverter?

    "Fixed installation" is a bit outdated as a description of what BS 7671 covers - these days it's more like everything (fixed or otherwise) that isn't covered by more specific standards. Very often a motor + VSD would form part of an overall "machine" and so be covered by something more specific - like BS EN 60204. But an installation powered by a UPS doesn't have its own standard.

        - Andy.

Reply
  • So why would you consider a UPS part of fixed install and not VSD inverter?

    "Fixed installation" is a bit outdated as a description of what BS 7671 covers - these days it's more like everything (fixed or otherwise) that isn't covered by more specific standards. Very often a motor + VSD would form part of an overall "machine" and so be covered by something more specific - like BS EN 60204. But an installation powered by a UPS doesn't have its own standard.

        - Andy.

Children
  • Fair enough I'll be more specific and rephrase the original question to hopefully get clarification, as I am not taking about a washing machine or simular.

    Question: When using cable design software such as ElectricalOM, there is a check box within the "Earthing" tab / adiabatic check of CPC. It states Provision of  regs 419.2 & 419.3 are applicable. (BS7671)

    If checked it will remove the warning regarding the earth fault / relating to disconnection time (should a warning exist with the modelled install)

    Can someone confirm with a degree of certainty that the checkbox relating to 419.2 be applicable to a standalone 3 phase induction motor, on a water treatment plant or other industrial setting. Where the motor is either:

    A) Directly connected to the output of a wall mounted VSD drive (not in an assembly) via SWA cabling 

    B) Directly connected to the output of a VSD drive mounted within a pump starter (Form 4 MCC assembly) via SWA cabling 

  • A) Directly connected to the output of a wall mounted VSD drive (not in an assembly) via SWA cabling

    I have to admit that it did occur to me that you could have, let's say, a VSD mounted to the wall (or on a stand on the floor, or even screwed to the ceiling) supplying a fan. Equally well, as you say, a pump.

    Back to the OP, I have no doubt that design software is very helpful when it comes to cable calculations and so on, but it will never tell you which box to tick else it would have done it for you.

  • never tell you which box to tick else it would have done it for you.

    No need to be patronising Chris. I was not asking if I should tick the box or not.

    I was seeking clarification of reg 419.2 and in what situation to apply it to. I know exactly what the check box does. If ticked the software does not report where a circuit has not met the required max disconnection time.

    The question has not arose from a design I am working on FYI. I came across an Amtech report from a past contract a few years back done a someone else and noticed that there is a comment on the report stating "

    Auto dissconnection time has been exempted as equipment complies with BS7671 419.2Protection is provided by the

    VSD

    This report would have been based on one of the senario B I have given. So are you saying they are incorrect by adding this comment? 

  • No need to be patronising Chris. I was not asking if I should tick the box or not.

    You certainly appeared to be asking whether you should tick the box if you have a motor which is supplied by a VSD.

  • You certainly appeared to be asking whether you should tick the box if you have a motor which is supplied by a VSD.

    Where did I ask if I should tick a box or not? I asked if the check box, or more importantly reg reg 419.2  was applicable to a certain scenario. I can then make a judgment myself if I should or should not tick the box should I need to.

    I also asked if ...

    Can someone confirm with a degree of certainty

    You don't appear to be able to answer this with any degree of certainty at all, so there wasn't much purpose in throwing your 2 pence in the first place. 

  • Can someone confirm with a degree of certainty

    You don't appear to be able to answer this with any degree of certainty at all, so there wasn't much purpose in throwing your 2 pence in the first place. 

    Nobody can with certainty because you didn't give enough information.

    I am still of the opinion that if the VSD is part of a machine, it is outside the scope of BS 7671. If it is separate, only the manufacturers can say.