Hi Ronald, It may be helpful for you to purchase a copy of 62368-2, which has the rationale for the requirements in 62368-1.
Others can provide more detail and probably explain better than I, but in general Table 4 has voltage *or* current limits, and Table 5 has capacitance *and* voltage limits. Table 4 is based on current (concerned with electrical shock), while Table 5 is based on energy (concerned with energy hazard), so you aren't comparing apples to apples by just looking at the voltage values in each table. *Table 4 (Electric Shock)* See Figure 21, and the explanation at the end of 5.2.2.1. "For any voltage up to the voltage limit, there is no limit for the current. Likewise for any current up to the current limit, there is no limit for the voltage..." - For low voltage circuits, the current is limited by the impedance through the human body. The currents assumed to flow through the human body at the ES1 voltage limits are lower than that which causes undesirable physiological effects. - There could be an ES1 circuit up to 25kV, or even higher in theory (with currents in normal, abnormal and single fault conditions limited to comply with the applicable limit). As long as the current is limited to values below that which causes undesirable physiological effects, the voltage doesn't matter. This is similar to the Limited Current Circuit from 60950-1, clause 2.4. *Table 5 (Capacitor Energy)* For the energy from a capacitor, the table takes into account capacitance and voltage, so both need to be taken into account since the equation for available energy from a capacitor includes both variables. This is similar to 2.1.1.5c)2) from 60950-1. A bit more info here <http://ewh.ieee.org/r10/taiwan/pses/archive/Historical%20data/Article_IEEE_PSES_CFP2005_Hazard-Based%20Safety%20Standard.pdf> (see section III). On Mon, Oct 26, 2015 at 10:31 AM, Ronald Pickard < [email protected]> wrote: > For all those more familiar than I with this standard, I would appreciate > a clarification. > > > > I’ve just purchased EN 62368-1 (assuming IEC 62368-1, too) and have > started immersing myself in it, but in 5.2.2.3 (Table 5) ES1/ES2 voltage > limits from a charged capacitor appear to violate the ES1/ES2 voltage > limits from 5.2.2.2 (Table 4). As Table 5 doesn’t address Vdc or Vac, I am > assuming absolute voltages (Upeak not defined) apply here. It appears that > up to 25KV (50KV for ES2) are allowed depending on capacitor value. And, > how would a capacitor be charged to 25KV in or then connected to an ES1 > circuit without consequence? Am I reading this correctly? Are these voltage > limits intended for capacitor rating limits only? What is the purpose of > 5.2.2.3 and Table 5? > > > > The further I get with this, the more questions that pop up for me. I > can’t seem to resolve this in my own feeble grey matter as to why such > voltages would be allowed. I would like to understand this better and would > appreciate if someone would clarify this for me and possibly others that > may have these or similar questions as well. > > > > I look forward to your reply. > > > > Best regards, > > > > *Ronald Pickard* > Regulatory Compliance Engineer > *Compound Photonics* > D | +1 (602) 883-8039 > > - > ---------------------------------------------------------------- > > This message is from the IEEE Product Safety Engineering Society emc-pstc > discussion list. To post a message to the list, send your e-mail to < > [email protected]> > > All emc-pstc postings are archived and searchable on the web at: > http://www.ieee-pses.org/emc-pstc.html > > Attachments are not permitted but the IEEE PSES Online Communities site at > http://product-compliance.oc.ieee.org/ can be used for graphics (in > well-used formats), large files, etc. > > Website: http://www.ieee-pses.org/ > Instructions: http://www.ieee-pses.org/list.html (including how to > unsubscribe) <http://www.ieee-pses.org/list.html> > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > Scott Douglas <[email protected]> > Mike Cantwell <[email protected]> > > For policy questions, send mail to: > Jim Bacher <[email protected]> > David Heald <[email protected]> > -- Scott Aldous Compliance Engineer Google 650-253-1994 [email protected] - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://www.ieee-pses.org/emc-pstc.html Attachments are not permitted but the IEEE PSES Online Communities site at http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used formats), large files, etc. Website: http://www.ieee-pses.org/ Instructions: http://www.ieee-pses.org/list.html (including how to unsubscribe) List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas <[email protected]> Mike Cantwell <[email protected]> For policy questions, send mail to: Jim Bacher: <[email protected]> David Heald: <[email protected]>
