# Large current draw at each cycle

I am designing a power circuit based off an older circuit for a similar machine, and have had a few issues in LTSpice simulator, where massive currents are drawn for the capacitors charging.

The image above shows the capacitors spike at the frequency of the AC input, quickly charging, but drawing a huge amount of current per cycle.

The instantaneous current draw (approx 120Hz) is 18A, and I am wondering whether this value is harmful to the operation of the circuit (currently under a 3.15A fuse), as the normal DC load is under the fuse normally.

Circuit voltage vs total current draw

Circuit outline (Simplified)

(I've got ways to manage inrush current, but not the constant spikes)

• The simulator can calculate you the RMS if you worry about your fuse, but you should also worry about the diodes and the cap(s) Commented Jul 16, 2018 at 8:47
• Is that a 3 ohm resistor across C1? Commented Jul 16, 2018 at 9:30
• In the original circuit the fuse is right at the start, but the capacitors themselves aren't wired any different from the circuit above, so I'm not sure how sudden spikes of current are handled due to the capacitor charging. The I1 and I2 are loads, the 24V regulator has a 0.125A load, and along the main wire there is a 3A load Commented Jul 16, 2018 at 9:31