Converter In-Rush Thermistors etc, UPDATE -4
UPDATE on 17 Nov, Update 2 on 22 Nov, Update 3 on 16 Jan 14, Update 4 on 19 Oct 14. --------------- In a recent thread there was mention of how you can wreck your gizmo (in my case a converter) ...
Forum Discussion
Salvo wrote:
Yes, if this is your typical capacitor peak charge circuit, then the diode bridge is the only part at risk. You must keep the surge current less that the diode rating. If the diode has a 350A surge rating then you need a current limiting resistor greater than:
R = 170V/350A = 0.5 ohm
SalBFL13 wrote:
Please remind me, on a cold start, with the capacitors unloaded, is the diode bridge at risk at all?
Ok so these are the diode bridge specs. (D25BX60) I can't follow the argument here what to use for amps and the 170v. Ken wants to use 50a , back a bit from the 60 number--but is that 60 amps??? and Salvo wants to use the big number threshold to arrive at a way lower R.
ISTR the actual thermistor requirement is to hold back a certain amount of amps to the diode bridge out of the total inrush, so the bridge stays under its limit. But we don't know the total inrush so how can we subtract the diode bridge's limit, whatever that is really, from the total, to see what the thermistor's minimum R must be to hold back that much current?
http://www.fagorelectronica.es/images/download/semiconductor/d25xb.pdf
