Im building a aluminium heatbed for my printer. And i think i have everything i need but to be sure i ask you opinion about my setup.
Im want to use the following components 1xAluminium sheet of 300x250x10mm 1x CARLO GAVAZZI RP1A23D5 SOLID STATE RELAY 3-32 VDC , 5 A 230 V AC 9x 50-watt wirewound resistor, RH050, 12 Ohms 2x Thermal fuse, 10 A, 142 °C 1x Thermal compound, metal oxide powder, 5 g syringe 1x Thermisor 100K 1x Rumba 3d printer controller based on Atmega2560
I put the Resistors in series mounted to the aluminium sheet with 2 screws and some thermal compount thats a total of 9x12 Ohms =108 Ohms The Thermal fuse also in serie with the resistors and mounted just below the headbed. Thermister connected to the Rumba and placed in the center of the heatbed Port 3 of the SSR connected to a logic pin of the Rumba Port 4 of the SSR connected to the ground of the Rumba board
Port 1 and 2 of the SSR between 230AC power and the Resistors Ground wire connected to Heatbed
The Rumba board is running a PID controller to get the temp. to a maximum value of 110 degrees C
230VAC / 108Ohms = 2.13A 2.13A * 230V = 489W
489W/9 Resistors = 54Watt P/resistor
But because the are mounted to a giant heatsink i hope the extra 4Watt would not be a problem.