On Mon, Jan 10, 2022 at 2:47 PM Martin via <martin_ehrenfried=[email protected]> wrote:
Hi Chris,
It's typical of a switched mode power supply, which looks to have an approximate 9KHz component.
Power supplies stop abruptly when the power is switched off. This thing clearly has a spin-up and spin-down phase, both 3-4 seconds long.
It might be a large variable-speed motor. An elevator in my house draws similar patterns (it has a soft-start and soft-stop phase in order not to shake the passengers too much).
