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
I see you found the diode.
It has a peak surge rating of 350A.
Your thermistor needs to be larger than 170V/350A = 0.49 ohm.
I haven't heard any rational reasoning for going greater than 2 ohm.
Note, the surge current is for an extremely short time; 4 ms max. The charging pulses that follow the initial pulse have significantly less current.
Just to review:
1. The desired resistance of the thermistor has nothing to do with the size of the capacitor bank.
2. If this is your standard peak-charge circuit, the diode bridge is the weakest link and may need inrush current surge protection.
3. The energy the thermistor consumes during turn-on is equal to 1/2CV^2. It doesn't matter if the thermistor has 1 ohm or 5 ohm, they will consume equal energy.
4. The size of the capacitor bank determines the minimum energy spec for the thermistor.
Sal
It has a peak surge rating of 350A.
Your thermistor needs to be larger than 170V/350A = 0.49 ohm.
I haven't heard any rational reasoning for going greater than 2 ohm.
Note, the surge current is for an extremely short time; 4 ms max. The charging pulses that follow the initial pulse have significantly less current.
Just to review:
1. The desired resistance of the thermistor has nothing to do with the size of the capacitor bank.
2. If this is your standard peak-charge circuit, the diode bridge is the weakest link and may need inrush current surge protection.
3. The energy the thermistor consumes during turn-on is equal to 1/2CV^2. It doesn't matter if the thermistor has 1 ohm or 5 ohm, they will consume equal energy.
4. The size of the capacitor bank determines the minimum energy spec for the thermistor.
Sal
