[TechAssist] Re: Voltage Rating of Resistors
- From: "J Silverman" <greentron@xxxxxxx>
- To: <techassist@xxxxxxxxxxxxx>
- Date: Mon, 25 Apr 2005 14:03:34 -0400
With the current at 5 ma, the resistors would see a peak power of 45
milliwatts each. Only the manufacturer could answer your question.
Jerry Silverman
Greentron Inc
4 Newland Ave
Greenville SC 29609
Fax/Phone 864 232 3889
mail to: greentron@xxxxxxx
----- Original Message -----
From: "Bil Green" <tv.vcrrepair@xxxxxxxxxxx>
To: "Jerome Silverman" <techassist@xxxxxxxxxxxxx>
Sent: Monday, April 25, 2005 7:08 AM
Subject: [TechAssist] Re: Voltage Rating of Resistors
> 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
> >>
>
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