Foe a 60x40cm heated bed, I estimate you will need 600W of heating power as a minimum, and 1kW to 1.5kW would be more like it if you want to reach ABS printing temperatures quickly. At these power levels, only AC mains power is practical.
The good news is that you can get a silicone bed heater custom made to your size, voltage and power requirements quite inexpensively from these people [
alirubber.en.alibaba.com]. Mount it on the back of an aluminium plate (I use 5mm thick), and either print on the top surface or put a sheet of glass on the top surface and print on that. Also, you can drive such a bed heater very easily using an inexpensive zero-crossing SSR such as SSR-25DA, without needing a heatsink at these sort of power levels.
The bad news is that you have to pay attention to insulation, protective grounding, enclosing all the live wiring, and preferably provide RCD protection.
Edited 2 time(s). Last edit at 04/16/2015 08:01AM by dc42.
Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod
Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].
