'protection capability' sends me directly to the short circuit rating of the OC device, which is spec'd at rated voltage. If you consider that at short circuit currents, your voltage has likely dropped dramatically. Your panel board/service short circuit rating is that of the lowest rated device. In regards to the trip currents, you need a device that will handle the voltage, so you'll be good.Will the protection capability of the circuit breakers be degraded in a 480V 3-phase panel, with 480V breakers, if it is installed with a 230V 3-phase feed?
+1.. 20 amps is 20 amps, across a thermal...Check one of the breakers, it will most likely show you the voltage range for normal operation, it could well be marked 230-480vac.
There is no difference in 20amps across a thermal load detection.
Max.