Best way to safely pass 10A to test OCP circuit?
koolksmart, Mon Mar 14 2022, 12:16AMHi there,
I've got a system I'm developing which controls a motor up to 10A. The motor connects via standard IEC port and is supplied mains power through quick connects connecting to an AC cord.
I'd like to validate that my OCP circuit works by passing 10A through the system, but I'm not sure about the safest way to do so. My thinking so far is that I could connect a number of high-power-draw devices to a surge protector (e.g. vacuums, hair dryers, etc.), plumb that into my AC feed in place of the motor, and ramp up to their highest power settings until I hit 10A and (hopefully) kill power from inside my device.
I would also like to put a current clamp around the line wire coming from the power strip and get a scope reading for what current level finally triggers my OCP.
Is this a terrible idea? Will it work? What's the "proper" way to go about this kind of test?
Any and all input is appreciated! Thank you!
Re: Best way to safely pass 10A to test OCP circuit?
klugesmith, Mon Mar 14 2022, 05:19PM
Sounds like a good plan.
Most clamp-on ammeters don't involve an oscilloscope.
If your "overcurrent protector under test" is rated at 10A then it should conduct 10A forever.
Might be designed to trip after a couple minutes at 15A, a few seconds at 20A, and immediately in case of short circuit (1000+ A). Details in datasheet.
[edit] If the OCP function is home-made, of course you could design it to trip instantly at 10.1 amperes.
That might make it hard to start your motor.
Will it respond to RMS current, or average rectified current, or peak current in one or both directions? You could make your test load more interesting by including resistive load on a phase-control dimmer. Even a regular switched vacuum cleaner or incandescent lamp will have inrush current much higher than steady-state current.
klugesmith, Mon Mar 14 2022, 05:19PM
Sounds like a good plan.
Most clamp-on ammeters don't involve an oscilloscope.
If your "overcurrent protector under test" is rated at 10A then it should conduct 10A forever.
Might be designed to trip after a couple minutes at 15A, a few seconds at 20A, and immediately in case of short circuit (1000+ A). Details in datasheet.
[edit] If the OCP function is home-made, of course you could design it to trip instantly at 10.1 amperes.
That might make it hard to start your motor.
Will it respond to RMS current, or average rectified current, or peak current in one or both directions? You could make your test load more interesting by including resistive load on a phase-control dimmer. Even a regular switched vacuum cleaner or incandescent lamp will have inrush current much higher than steady-state current.
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