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
We've gone over this already. My test data shows turn on current during the first cycle is 36A This is with a 2 ohm thermistor and 2400 uF capacitor bank.
Scope plot of Parallax converter, measuring voltage at the capacitor bank. Vert: 20V/div, Horz: 5 ms/div
The waveform has a linear ramp, charging to about 75V in 5 ms during the first cycle. Since the capacitor charge rate is constant we can deduct that the current is also constant (through most of the cycle). The steeper the slope, the greater the charging current. Subsequent charge cycles have lower current.
The current is:
I = C * dV/dt
I = 2400 uF * 75V/5 ms
I = 36A
There's your 40A spec.
Sal
Scope plot of Parallax converter, measuring voltage at the capacitor bank. Vert: 20V/div, Horz: 5 ms/div
The waveform has a linear ramp, charging to about 75V in 5 ms during the first cycle. Since the capacitor charge rate is constant we can deduct that the current is also constant (through most of the cycle). The steeper the slope, the greater the charging current. Subsequent charge cycles have lower current.
The current is:
I = C * dV/dt
I = 2400 uF * 75V/5 ms
I = 36A
There's your 40A spec.
Sal
BFL13 wrote:
I know there was the single cycle value being different from actual current (but can't remember in what way ) but how about that 34a limit for the 5R compared with this spec for the converter at 40a?
•MAX INRUSH CURRENT, SINGLE CYCLE: 40 AMPS
Could the 40a translated into real amps be too much for the 34a 5R and ok for the 85a 2R?
