I have a temperature controller supplied with 230VAC via a 0.5A circuit breaker curve C. The thing is, the MCB trips as soon as power is turned on. I have measured the inrush current profile without the MCB with a current probe: up to 90A for 20ms!
I can see three options:
- A capacitor is first charged when power is turned on, and a second "power" switch allows the capacitor to discharge. I don't want another switch, so I'd rather avoid this option.
- A RC + MOSFET ramps up the voltage. If possible and safe, I'd like to avoid adding components as it is a real hassle to go through the design update process.
- The 0.5A nominal is changed for 10A. This is the quickest option as I have some around and it doesn't take much to change a value on a drawing and get it signed off; however that allows more potential destructive power in the downstream components (a couple of relays, a AC/DC, in addition to the controller). The technician used the same wire gauge everywhere, so up to 10A wouldn't melt the wires.
Is there any other option I am not aware of? If there isn't, then this post serves to those in the same situation. After all that's what forums are for.