Coil Power Supply: Current Measurements

22 08 2011

All photos.

Today I took a step back and measured the current going through the coils.

Previously I measured 1,200 amps going through the coils with the capacitors charged to 450V.

My setup is a little different now: There are 2 meters of cabling + feedthrough between the coils and their power supply.

For all of these shots, the capacitors were charged to 450V. The shunt resistor shows 100mV across for 100A through. Multiply the voltage by 1000 to get the current in amps.

Surprisingly I’m seeing significant variation of current for identical conditions.

The most current I saw was 1,095 amps:

But with the same conditions I saw this much lower 344 amp current:

The median current reading was around 734 amps:

Disconnected, the coil shows 0.8 ohm of resistance.

I’m rather surprised by this variation. What could be the cause?

I tried some other conditions.

With the capacitors charged to 200V, I got 560 amps of current:

I also tried charging 5 out of 10 capacitors to 450V. With an average current of 500 amps.

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