cupoftea
Advanced Member level 6
Is it foreseeable that a customer (eg office block, factory etc)
could just use save money and use just one single RCD for their entire installation?
If so, and we supply lots of kit to them,
then we should reduce the amount of Y capacitance in the offline power supplies we supply.
(since y caps increase earth current which trips RCDs if above 30mA).
Also, having a Y capacitor from Line to Earth potentially gives the most earth current.
As such, we should arrange the Y capacitors in other places instead. (eg from Primary DC bus ground to earth instead). We will just have to use
a bigger/more effective common mode choke in order to vanquish the common mode noise.
Having a nice balanced common mode choke goes to the wind when you care about RCD false tripping.
So is Y cap absolute minimisation a real ploy in the SMPS world?
Or is it more a case of...there can't be that much gear on each phase so make 'em all
4n7 and no-one would ever false trip the RCD?
could just use save money and use just one single RCD for their entire installation?
If so, and we supply lots of kit to them,
then we should reduce the amount of Y capacitance in the offline power supplies we supply.
(since y caps increase earth current which trips RCDs if above 30mA).
Also, having a Y capacitor from Line to Earth potentially gives the most earth current.
As such, we should arrange the Y capacitors in other places instead. (eg from Primary DC bus ground to earth instead). We will just have to use
a bigger/more effective common mode choke in order to vanquish the common mode noise.
Having a nice balanced common mode choke goes to the wind when you care about RCD false tripping.
So is Y cap absolute minimisation a real ploy in the SMPS world?
Or is it more a case of...there can't be that much gear on each phase so make 'em all
4n7 and no-one would ever false trip the RCD?