Re: [CAD_CAM_EDM_DRO] Inrush and prevention? was Re: power supplies form those 24v transformers

Les Watts wrote:

>Ballendo,
>
>Again these are suggested by Mariss from Gecko.
>
>They are NTC thermistor inrush limiters. Thermometrics
>and Keystone make them, and they are commonly used
>on power supplies (particularly switching) when large
>capacitances must be charged up at turn on. On traditional
>transformer supplies core saturation and winding resistance
>also help to control this surge, but the inrush limiters would
>seem to give an extra measure of soft starting.
>
>

I wrote a program to simulate this kind of inrush. I estimated the
thermal time
constant of the NTC thermistor by weighing them. It tries a cold start
with zero
volts on the caps from all meaningful power line phase angles in 1
degree steps, and
reports the worst case surge. If anyone is interested, I can dig it
out. I suspect it is
Fortran, but might be Pascal.

Jon