I've designed a circuit that intentionally trips circuit breakers. Yes, I know this is a bit bizarre so here's the background - these magnetic breakers are of a special type that are used in commercial flight simulators. They can be used to simulate the behavior of high-current breakers by allowing for a fast trip at relatively low current (<250 mA). The breakers have a built in resistance of 153 ohms, are intended to be driven from a 28V supply (so to trip them, all you need to do is short them to ground), and have two built-in diodes (one flyback, one forward-biased).
This is the datasheet for the breakers. The circuit is very simple: The breaker is connected to a 5.1K resistor that's in parallel with a solid state relay for isolation, the
AQY211EH. The SSR is normally off until it receives a signal from a microcontroller, which then turns on and bypasses the resistor with a short to ground, causing the breaker to trip.
Here's a circuit diagram to help visualize what's going on.The circuit works well on the surface, but when I had a look at the behavior of the circuit in my oscilloscope, I came across these
large transient voltage spikes that occur roughly 10ms after the SSR switches on. The max and min of the spikes are roughly +14V and -14V, and occur several times -
here's a more zoomed in view at 20 us/div to show what's going on.
Anyone have any idea what these spikes might be and what can I do to suppress them? This is my first time working with circuit breakers and SSRs, so I'm not well versed in their quirks.
Thanks in advance.