Reader questions: Thickness of PCB traces for a 120A solenoid
George asks how thick PCB traces should be for driving a 120A solenoid:
I’m doing a board design to power a solenoid that apparently draws 120 amps, but it’s only on for about 300 ms (I imagine it has some kind of “inverse curve” looking decrease with time, I haven’t thought about it too much). The weird thing is that the solenoid comes with 18-gauge wires, or something close. I’m wondering how thick I should make the traces. I’m assuming I don’t have to go the recommended 5-inch wide (using PCB calculators). In fact, I started thinking I would only have to go as wide as the max diameter of the pad, which is TBD.
Now, the only reason one has to design wider traces for higher current is to avoid heat, correct? Because this is for an electric shifter (In Ohio State University’s new formula car), so it’ll have a very low duty cycle. What do you think? Should I just go ham on the traces and make them huge? Or should I limit them to the width of the pads (or the circumference of the wire for that matter)?
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