Hello Experts,
When trying to simulate a inrush controller in LTspice, we see there is a sudden spike in the capacitor current , whenever the contactor(S1) is turned on.
I understand the positive spike, but why does the negative spike occur?

 

What problem are You trying to solve ?
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With an unmarked set of plots there is nothing to discuss.
Also, in many cases a simulator gets confused.

 

I understand the positive spike, but why does the negative spike occur?

Only positive spike:

ADDED:
@ak52: Contactor like relay, changes its impedance instantly,
but not smoothly, during 100ms, like in your circuit.
So, it should be something like this:

 

Just exactly where is that "negative spike" measured between?? When the contactor opens suddenly the voltage at the cap will drop a small amount because of the voltage drop across the 1000 ohm resistor. Recall that in this simulator, voltage sources can supoply infinite current because they have zero internal resistance. The simulator world is different from the real world.

 

Just exactly where is that "negative spike" measured between?? When the contactor opens suddenly the voltage at the cap will drop a small amount because of the voltage drop across the 1000 ohm resistor. Recall that in this simulator, voltage sources can supoply infinite current because they have zero internal resistance. The simulator world is different from the real world.

The current that is measured is the current flowing through C1, Yes I see that when the contactor opens the voltage drops slightly, , but that does not explain why the current goes positive and then suddenly turn negative , whenever the contactor is switched on?


PS: Once i gave some internal resistance to the voltage source , the negative spike has gone, Could you pls explain this?