In theory, you can do anything. In the real world, I would not expect series caps to share the total voltage equally. I've seen designs for HV diode array and HV cap arrays where parallel elements in each leg are added to help balance the instantaneous voltage. cheers Rick -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Riley, Jonathan Sent: Wednesday, June 27, 2012 7:16 AM To: 'rohit.mishra@xxxxxx'; 'balaseven@xxxxxxxxx'; 'si-list@xxxxxxxxxxxxx' Subject: [SI-LIST] Re: Dielectric Strength of series capacitor_EMI Hi Bala You also need to consider the difference in leakage currents too. This affects both of the capacitors and also the PCB. You can overcome both of these issues by putting a balancing resistor in parallel with each capacitor, the value of the resistor being fairly high (high enough to allow a significantly larger current to flow than the leakages, so this becomes the dominant current). Of course, if the equipment does not permit a DC path, you cannot do this. It is generally simpler and safer to use a single capacitor whose rating meet or exceed your requirements. Regards Jonathan -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of Rohit MISHRA Sent: 27 June 2012 06:05 To: balaseven@xxxxxxxxx; si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Re: Dielectric Strength of series capacitor_EMI Bala, Theoretically, you can connect two similar capacitors in series since both will share half of breakdown voltage and can serve your purpose but Remember, real capacitors value always comes with some tolerance !!! Suppose you have two capacitors of 10 UF Value with 10 % tolerance and breakdown voltage of 2 KV So worst condition will be when one capacitor will have 9 UF and another will have 11 UF Value. When you connect these two capacitors serially across 4 KV Source, The one with lesser value ( 9 UF) will charge fast and will also share more voltage and hence would break down much earlier than you would predict when simply dividing the voltage among them. So you shouldn't expect capacitors to charge to the same voltage unless they are the same series by the same manufacturer and out of the same production run. Hope that helps. Rgds, Rohit Mishra -----Original Message----- From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On Behalf Of bala Sent: Wednesday, June 27, 2012 3:07 PM To: si-list@xxxxxxxxxxxxx Subject: [SI-LIST] Dielectric Strength of series capacitor_EMI Hi All, I have to use 4KV line to ground capacitor for safety,and,due to some design restrictions,i planned to use two 2KV capacitor in series. My question is,Can we add the Dielectric Strength of the capacitor connected in series and consider them as cumulative.? We usually apply 'Kirchhoff Voltage Law' to calculate the total Voltage,can we apply the same for Dielectric strength? -- bala ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field or to administer your membership from a web page, go to: //www.freelists.org/webpage/si-list For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List forum is accessible at: http://tech.groups.yahoo.com/group/si-list List archives are viewable at: //www.freelists.org/archives/si-list Old (prior to June 6, 2001) list archives are viewable at: http://www.qsl.net/wb6tpu