Re: [PSES] Y2 capacitor in DC circuit
Non-sequitur. Either the cap is rated for the working voltage, or should not be used where the component required to provide basic protection from shock. There are several mfrs that make 300Vac X and Y-caps that are also specified for 1kVdc. The problem is that the IEC60384-14 cert will not indicate that the 1kVdc is a rating. Brian From: Boštjan Glavič [mailto:bostjan.gla...@siq.si] Sent: Monday, November 10, 2014 11:04 AM To: EMC-PSTC@LISTSERV.IEEE.ORG Subject: [PSES] Y2 capacitor in DC circuit Dear experts, I have one question. One of our clients is generating high voltage DC bus out of primary circuit without the insulation. This 800VDC circuit is therefore considered as part of primary circuit. They are using Y2 capacitor between this DC voltage and PE (accross basic insulation). Measured working voltage accross the capacitor was 800VDC (worse case). Y2 capacitor has only rating for AC voltage (250V). They could not find any Y capacitor with DC voltage. Do you see any issue with such construction? Best regards, Bostjan SIQ - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Y2 capacitor in DC circuit
Hi Boštjan: A Y2 capacitor is rated 250 V a.c., 5 kV peak impulse. According to IEC 60384-14, rated voltage is "either the r.m.s. operating voltage of rated frequency, or the d.c. operating voltage, which may be applied continuously to the terminations of a capacitor." Impulse voltage is "aperiodic transient voltage of a defined waveform." 800 V d.c. exceeds the Y2 rating. You can expect failure of the capacitor - maybe not immediately - with possibly explosive results. I would look for a capacitor (you won't find a suitable Y capacitor as Y-caps have a maximum rating of 250 V) rated for the a.c. voltage, d.c. voltage, and impulse voltage. I would guess that you could get such a cap from some Y-cap suppliers. Your client probably needs to ask them to design and build the caps according to the use specs. Best regards, Rich - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
Re: [PSES] Y2 capacitor in DC circuit
In message , dated Mon, 10 Nov 2014, =?iso-8859-2?Q?Bo=B9tjan_Glavi=E8?= writes: I have one question. One of our clients is generating high voltage DC bus out of primary circuit without the insulation. This 800VDC circuit is therefore considered as part of primary circuit. They are using Y2 capacitor between this DC voltage and PE (accross basic insulation). Measured working voltage accross the capacitor was 800VDC (worse case). Y2 capacitor has only rating for AC voltage (250V). They could not find any Y capacitor with DC voltage. Do you see any issue with such construction? Of course: the Y2 capacitor is being used a long way outside its ratings. It may stand 800 V DC for a while, but only for a while. It may burn up. I think they should look very carefully to see if it is necessary to have a capacitor from the 800 V DC to PE. -- OOO - Own Opinions Only. With best wishes. See www.jmwa.demon.co.uk Quid faciamus nisi sit? John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
[PSES] Y2 capacitor in DC circuit
Dear experts, I have one question. One of our clients is generating high voltage DC bus out of primary circuit without the insulation. This 800VDC circuit is therefore considered as part of primary circuit. They are using Y2 capacitor between this DC voltage and PE (accross basic insulation). Measured working voltage accross the capacitor was 800VDC (worse case). Y2 capacitor has only rating for AC voltage (250V). They could not find any Y capacitor with DC voltage. Do you see any issue with such construction? Best regards, Bostjan SIQ - 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 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 Mike Cantwell For policy questions, send mail to: Jim Bacher: David Heald:
