Hi again Pete. I was just saturation testing some chokes I made and thought you might be interested to see a DSO screenshot and observe what happens when a choke saturates. The equipment used is just a large capacitor which is charged to a set voltage. This charge is then dumped directly into the choke and a Hall current sensor measures the current resulting. The screen graduation is 100A per vertical division. You can see the choke resists the current for the first milli second, allowing it to increase only gradually. After that time the current had risen to about 150A when the trace slope suddenly steepens dramatically. That is the point where the choke starts to saturate and the current can rise as high as the source allows. In this case its about 400A when the capacitor runs out of charge. For that test the cap was charged to 40V, had I charged it higher then the dumped current would also have gone higher after saturation. The ring cores you used behave very differently, there is no sharp saturation 'knee'. Instead, the current trace sweeps up quite quickly and, unless you have sufficient inductance, can reach high levels. On this picture I tested a similar core to yours, using 4 rings and 5 turns of cable. You can see it reaches 150A in a relatively short time and keeps on climbing. My chokes are for 48V, the chokes would see double those currents in your 24V system so would saturate at lower power levels. Chokes dampen the current in your primary, they do nothing to the voltage. |