This is a relay capable of switching 30A of current. It is switched by a 12V signal. The relay can be connected to be normally open or normally closed, depending on your setup and can be set to a high level trigger or low level trigger. It uses an EL817 photoelectric coupler for isolation.

This is used to switch your heated bed on and off when your heated bed needs to run off a higher voltage than your electronics or the current is more that the electronics can handle. So if you have for instance a RAMPS board controlling your printer, but you have a large heated bed running off 24V or your heated bed pulls more than 10A of current then the switch on the electronics is not suitable to drive the heated bed. Then you can use the heated bed output from the electronics to switch the relay and connect the heated bed to the power supply via the relay.

Specifications:

• Current capacity: 30A
• Switching voltage: 12V
• Can be connected as Normally Open or Normally Closed