[Ether]

Originally Posted by Mr V

Yes it might be pulling 80 amps at a particular rpm when power is applied but if the motor controller is commanded to be operating at 50% to achieve that rpm then the average current would only be 40 amps. The circuit breaker is then getting a "rest" period where it can cool between the times it is supplying that 80a so it will more or less act as if it was only carrying 40 amps and should be able to do so more or less indefinitely.

Put a small resistance in series with the breaker¹ and display the voltage drop across it (which will be proportional to the current) with an oscilloscope. You might be surprised at what you see.

¹or just measure the voltage drop across 1 foot of wire coming from the breaker