The Fuji EG53C/50-30MA Earth Leakage Hydraulic Magnetic Circuit Breaker has been superceded. One source recommends the EW50EAG-3P050B as replacement.
Data sheet ➥
https://www.onlinecomponents.com/en/...30ma-11339603/
I have no specific familiarity with Fuji circuit breakers, but it appears to me that:
Yellow button indicates Ground Fault [earth leakage] trip.
Grey button indicates an Overload trip.
Red button is a Push to Test button.
Generally:
You have to cycle a breaker toggle to full “Off” position, prior to resetting to “On”. You should feel/hear a slight 'click', when the toggle reaches full Off.
When a breaker trips, the toggle moves to a central position, more towards Off, but not all the way.
Breakers can generally be re-set with
power supply On or Off.