I don't know the peak power rating of the resistors, but the 900V inverter I am using is current limited to 5mA (the final output, after the voltage doubler is 1700V, at around 2.5mA). Therefor the max power that the 3 resistors (in series) will be subjected to is around 4W total, not 535W. And this would be for less than 0.5 seconds. I just need to know if continually applying an overload voltage to a carbon film resistor (for a fraction of one second, at a pulse rate of 1Hz) will weaken it. They are designed for 100% overvoltage during an overload. Bil PC 1000 Mammoth Lakes, CA 760-924-1000 M-Pulse 5000 magnetic pulse generator http://www.heal-me.com.au/m-pulse5000.htm Sunday, April 24, 2005, 8:16:33 PM, you wrote: JS> What is the peak power rating of the resistors? You are asking the three JS> reistors to handle a peak power of 535 watts. JS> Jerry Silverman JS> Greentron Inc JS> 4 Newland Ave Greenville SC 29609 JS> Fax/Phone 864 232 3889 JS> greentron@xxxxxxx JS> ----- Original Message ----- JS> From: "Bil Green" <tv.vcrrepair@xxxxxxxxxxx> JS> To: ".TECHASSIST @ freelists . org" <techassist@xxxxxxxxxxxxx> JS> Sent: Sunday, April 24, 2005 8:22 AM JS> Subject: [TechAssist] Voltage Rating of Resistors >> If anyone is very familiar with the voltage ratings of carbon >> film resistors, I could use some help. >> >> >> I would like to know if the Max. Overload Voltage of carbon >> film resistors (this is 2 x times the working voltage) would >> apply in this instance: >> >> I would like to use three 1.8k, 1/2W resistors* in series >> with a 1700VDC supply to charge a 0.5uF capacitor. It will >> fully charge in approx. one second. >> >> * 1/2W carbon film resistors are rated at 350V (working voltage) >> >> I realize that this is not exactly a surge condition, however >> the voltage exceeding the rating of these resistors would >> only exist for about 1/2 second (and would be below the Max. >> Overload Voltage of the 3 resistors wired in series). >> >> This is to be used in a magnetic pulse generator in which the >> capacitor discharges into a coil once per second (one second >> to fully charge and a very small fraction of one second to >> discharge). >> >> This instrument would only be used for a few minutes per day, >> and must be reliable. >> >> I will be ordering some 1W resistors (500V rating), but have >> a couple units that need to be shipped out on Monday. >> >> From what I've read, it's common for engineers to not consider >> the voltage rating of resistors when designing circuits, so I >> don't feel negligent, since I am doing the best I can at this >> time. >> >> Bil >> >> PC 1000 >> Mammoth Lakes, CA >> 760-924-1000 >> M-Pulse 5000 magnetic pulse generator >> http://www.heal-me.com.au/m-pulse5000.htm >> >> -------------------------------------------------------------------------- JS> --- >> This Email List is Public. Remove: http://www.tech-assist.org/remove.htm >> Lost Password: http://www.tech-assist.org and select "Login Problems?". >> Appliance Repair List: JS> http://www.tech-assist.org/secure/tip/chatjoin.htm#app >> Email Archives: //www.freelists.org/archives/techassist/ JS> ----------------------------------------------------------------------------- JS> This Email List is Public. Remove: http://www.tech-assist.org/remove.htm JS> Lost Password: http://www.tech-assist.org and select "Login Problems?". JS> Appliance Repair List: http://www.tech-assist.org/secure/tip/chatjoin.htm#app JS> Email Archives: //www.freelists.org/archives/techassist/ ----------------------------------------------------------------------------- This Email List is Public. Remove: http://www.tech-assist.org/remove.htm Lost Password: http://www.tech-assist.org and select "Login Problems?". Appliance Repair List: http://www.tech-assist.org/secure/tip/chatjoin.htm#app Email Archives: //www.freelists.org/archives/techassist/