wb8foz@mthvax.cs.miami.edu (David Lesher) (09/26/90)
My esteemed employer is planning on adding a bunch of 286 machines to an existing UPS system. The problem is, that because of the limited capacity of the UPS, they want to run ONLY the PC's off of it, and will run the laser printers off of the unregulated, un-isolated ground, unprotected power. I'm of the opinion that the first T-storm (if not sooner!) will blow up lots of boxes with this scheme, (the runs in question are long -- hundreds of feet) both from (line) induced voltage differences and ground loop problems. But the folks above, non-technocritters, don't believe me. Can anyone on the net *CITE SOURCES* I can use to strengthen my case? This could, for example, include a Tech Note from HP's Laserjet division, or such, or a section of the NEC. Note *I* don't need hearsay, I need published tomes to carry in. -- A host is a host from coast to coast.....wb8foz@mthvax.cs.miami.edu & no one will talk to a host that's close............(305) 255-RTFM Unless the host (that isn't close)......................pob 570-335 is busy, hung or dead....................................33257-0335
wolfgang@wsrcc (Wolfgang S. Rupprecht) (09/27/90)
wb8foz@mthvax.cs.miami.edu (David Lesher) writes: >My esteemed employer is planning on adding a bunch of 286 machines >to an existing UPS system. The problem is, that because of the >limited capacity of the UPS, they want to run ONLY the PC's off >of it, and will run the laser printers off of the unregulated, >un-isolated ground, unprotected power. I'm sure the UPS manufacturer would be pleased to cite papers or perhaps whip one up for you. I have pondered the same thing here and am toying with the idea of running everything through the UPS, but have a cut-out relay for the fluff when the power fails. This way one gets the filtering from the UPS and but doesn't melt down the inverter, or run down the UPS battery by running laser printers and other power hogs. One also eliminates you problem of large ground-loops for the data connections. You probably still have to play it close on the UPS rating though. -wolfgang -- Wolfgang Rupprecht uunet!{nancy,usaos,media!ka3ovk}!wsrcc!wolfgang Snail Mail Address: Box 6524, Alexandria, VA 22306-0524