On 06/26/2011 05:55 PM, Jussi Peltola wrote:
On Sun, Jun 26, 2011 at 11:36:24PM +0200, Ingo Flaschberger wrote:
but transforming is not easy. ac/ac transformers are easy tu build and very immune against lightning strikes - inverter systems are not. Switching DC is also problematic since there is no zero crossing to extinguish the arc.
Sometime look at break ratings for AC and DC breakers and compare the relative sizes. Shows this effect. Easy answer is: don't use mechanical switches for routine switching... (easy if there is an inverter present, like in a VF drive or switching power supply). Big enough AC breakers maintain the arc over more than one cycle so have this problem too. (plasma quench time at atmospheric pressure can be a while...) Given the technology of the time, AC won rightfully. Still better for most distribution. -- Pete