Thx, that actually helped a lot! Thanks, 'S
Sent mobile! On Dec 31, 2015, at 14:18, Ken Hohhof <[email protected]<mailto:[email protected]>> wrote: The difference is which side of the power supply is grounded. Telecom standard “office battery” is negative with respect to ground, it goes back to galvanic corrosion and copper cables. Or you could just view it as the standard, why is negative less logical than positive? There is more confusion regarding 24 volts. I think that was kind of a cellular standard voltage and tended to be +24 with respect to ground, but I’m not totally sure about that. The other place you see a lot of 24VDC is the process control / DIN rail world, and I think that’s always +24. And some references will tell you that 802.11at is +48V with respect to ground, but in actuality, I think most 802.11at POEs are floating, and most 802.11at powered devices are too. But just to be totally safe at some DC sites with expensive licensed radios and WB GigE-POE, I have put in a DC-DC converter to provide +48V. From: Scott Vander Dussen<mailto:[email protected]> Sent: Thursday, December 31, 2015 3:56 PM To: [email protected]<mailto:[email protected]> Subject: Re: [AFMUG] 48v Rectifier Recommendations Not to be a total noob, but what exactly is -48, and why does it exist instead of just +48? I read up on it sometime ago I think it had its origins with the telecom industry frying stuff or something? But I don't understand what the fundamental difference between -48/+48 is. Thanks, 'S Sent mobile! On Dec 31, 2015, at 10:26, Ken Hohhof <[email protected]<mailto:[email protected]>> wrote: Either of those should be good. I have some Eltek gear, but people have said nice things about Emerson also. One other option would be this: http://www.alpha.ca/web2/products/standard-systems/dc-power-solutions/item/48vdc-cordex-hp-300w-2 I haven’t used that product, but I do have some of their FXM series UPS and they have been very solid. Watch out that some of the rectifier products only work for one polarity, like –48VDC, so if you primarily need +48 that might be a problem. From: Josh Baird<mailto:[email protected]> Sent: Thursday, December 31, 2015 11:52 AM To: [email protected]<mailto:[email protected]> Subject: Re: [AFMUG] 48v Rectifier Recommendations Check Emerson Netsure (211) or Eltek for rectifier solutions. On Dec 31, 2015, at 12:45 PM, David Milholen <[email protected]<mailto:[email protected]>> wrote: I throw this name out there alot but dont know if anyone ever bites because the Cheaper solutions prevail. When it comes to power I do not want to keep going back to revise or figure out what doesnt work. � Have a look at these babies from Duracomm. The price is right on these to. We are having to update a majority of our sites since the release of pmp450i We also invested in the dc -dc converters and isolators for the -48 needed for ptp microwave gear. http://www.duracomm.com/product-category/rack-mount-power-supplies/he1u-mu-series/ � On 12/31/2015 11:35 AM, Scott Vander Dussen wrote: I need to upgrade several sites from AC to DC. Usage is 15A or less at 48vdc. Desire a robust, rack mount, with SNMP solution. Any specific recommendations? -- <Davidmvcf.jpg>
