andrew.box
100 W
Hey folks, I'm trying to drive a meanwell 12V 18A PSU, model S-250-12, using a standard type relay like one would use with arduino to switch the 120VAC mains to the power supply on and off. Not an SSR or anything, regular relay that goes 'click'. Well, I've had 3 relays now fail closed with this project which leaves the PSU and load turned on all the time, not what I want to do!
After the 2nd failed I figured it may be inrush current welding the contacts closed, relays are 10A rated and my load on the 12v side is only 5A but inrush maybe would be higher, so I put a 2 ohm 25A rated thermister in series with a leg of the AC mains between the relay and meanwell. But it happened again, I just found the relay stuck closed. I'm stuck on this as well, it can't be 3 bad relays at this point.
Anyone ever had this issue or have a better idea that me what's going on?
Full disclosure - this isn't being used as a charger in this project but rather to drive a 12v resistive heating element for an incubator for a DIY creature rearing setup, but I didn't know where else to turn and figured this may be useful to someone building an arduino controlled meanwell based charger someday. If it's too off topic feel free to remove.
After the 2nd failed I figured it may be inrush current welding the contacts closed, relays are 10A rated and my load on the 12v side is only 5A but inrush maybe would be higher, so I put a 2 ohm 25A rated thermister in series with a leg of the AC mains between the relay and meanwell. But it happened again, I just found the relay stuck closed. I'm stuck on this as well, it can't be 3 bad relays at this point.
Anyone ever had this issue or have a better idea that me what's going on?
Full disclosure - this isn't being used as a charger in this project but rather to drive a 12v resistive heating element for an incubator for a DIY creature rearing setup, but I didn't know where else to turn and figured this may be useful to someone building an arduino controlled meanwell based charger someday. If it's too off topic feel free to remove.