On 3/29/12 9:05 AM, Kevin Wormington wrote: > Curious if anyone has used one AC and one DC power supply in an MX80? Yes, I > know the docs say it's not supported but we all know how that goes. > > Thanks, > > Kevin
The big issue is not will the device support it, but why devices generally don't, and often actively prevent this. The issue is potential differences between the systems, attempting to equalize through your device, or a person. This includes not just normal operation, but failure and event (device fail, lightning, infra damage) handling. It is possible to design a combined AC/DC power system for this, but it is not simple or easy, technical or regulatory wise. It is possible to design isolated input power supplies for devices. It is possible to design the devices to maintain approp internal isolation to take advantage of this. It is possible to do all of this at the same time, and in theory meet all of the require safety regs. Possibly != easy or cheap. Most folks will accept the increase in equipment cost. Most folks will simple hook up the gear if it will allow it, without regard to the special requirments for install or power systems build out. That places the gear makers in an interesting position. They could make the gear to do it, but it would cost more. It would only be safe and not risk gear damage if it was coupled with proper install and AC/DC power systems design. I have seen plenty of devices running one AC and one DC supply, even though it was always a "DO NOT TO IT" item for that device. I have seen more than a few damaged, and more than a few safety issues. It is why many gear makers add additional restrictions, like gear refusing to power up if both AC and DC supplies are inserted. -- ------------------------------------------------------------------------ Christopher E. Brown <chris.br...@acsalaska.net> desk (907) 550-8393 cell (907) 632-8492 IP Engineer - ACS ------------------------------------------------------------------------ _______________________________________________ juniper-nsp mailing list juniper-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/juniper-nsp