My 3D printer has a 240W power supply that takes 220V AC as input and gives 12VDC/20A as output. I'd like to use a relay, controlled by a raspberry, to turn the printer ON/OFF. My question is: should I put the relay between the 220V and the power supply, or after the 12V? What are there pro and cons between the two configurations?
Switching mains is better because:
- It eliminates vampire losses by the power-supply itself which will use some power in standby. This saves a little bit on the energy bill.
- It eliminates risk of fire from PSU overheating (although it may introduce it somewhere else).
- It avoids heating the room.
The disadvantages include:
- Thermal cycling of the PSU, PCB and components. This may lead to component or board failure.
- Delay before you can print.