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:
Out of interest, I took a look at my 55A Iota converter. I didn't see any thermistor. The turn-on voltage test seems to confirm that.
The scope plot shows the capacitor voltage rising to 125V in the first charge cycle. The Iota converter has a 3 x 1000uF capacitor bank.
Max initial charge cycle current is:
I = C * dV/dt
I = 3000uF * 125V/5ms
I = 75A
If the OP's converter continues to fail, I would remove the thermistor and install a wire jumper. The OP should ask the manufacturer why there's a max 30A turn-on requirement.
Sal
Sal, 1/4 of a 60 Hz cycle is 4.167 ms which makes the average current during that period approximately 90 amps.
The peak current will be nearly twice that value or approximately 0.9 * 2 * 90 amps = 162 amps peak.
If the diode current is averaged over the entire period, which is valid since only one diode pair is on at a time, the surge current through the diodes would be approximately 22.5 amps.
