Hi , do i can use RB 600 with -48v power? or Not?
Thanks for replays.
Dimas
im not an electrician, but wouldn’t swapping the + and - give you +48 ? just throwing that out, I could be totally wrong.
I think the same Changeip, but i’m not sure, i need to be completly sure before buy 5 rb600 because i’m at Colombia, very far from Sellers.
regards
Dimas
do you have a volt meter ? connect the volt meter in reverse and see if you get +48. I would assume that as long as there is enough amps and you get +48 it should be fine. The only problem might be that if the negative wire is really fat and the positive wire is really thin, but if they are the same gauge it should be fine. I’m guessing it will be plenty beefy if it’s for telecom equipment.
You will get +48Vdc if you flip the leads. The whole idea of “positive” and “negative” voltages has to do with the direction of current flow, not the absolute voltage involved. It also has nothing to do with wire gauges either - that only has an effect on the total series resistance of the power input (current limiting it if high enough). This is all about ground references, current flow, and wether the RB600 has an isolated power supply or not on it.
I can’t swear to it, but I think telco power is isolated from Earth ground. But, if that’s not the case, and the RouterBoard power supply isn’t isolated either (as in there is no continuity between the “-” on the power input and say the “shell” on a wireless card), then you could have some rather nasty issues in store.
Talk with your telco people and find out if the telco battery supply is Earth isolated or not. Talk with the Mikrotik people and find out if the RouterBoard power supply is case/digital ground isolated or not. The safest answer is that if the Mikrotik power supply is not isolated, don’t connect it to telco power.
This isn’t something to take lightly - there is a lot of current available on most telco supplies (especially in CO’s where there are hundreds to thousands of amperes available at the bus), and if you screw up, you can get anything from a fried RouterBoard, to wires that act like fuses, to actually disrupting other telco bus powered gear. Be careful about what and how you do anything, and if not absolutely sure, don’t.
Brad
Recommended to use isolated DC/DC converter or 48VDC/230VAC inverter.
We use inverter without any problem.
(My english is not too good. I hope you understand me.)
Thanks to all, very clear about my question, i will ask to my provider about isolated power and if not, i have some Dc-DC converters.
Merry christmas to ALL Mikrotik People.
Now i have several installations with -48v power and works so fine…no problems.
Also be careful -
Equipment designed to run from Telco power supplies are normally specified 36-72V, to allow for the fluctuation of the battery banks as they charge/discharge. That’s quite a range.
Most data equipment with 48V input is designed with the 802.3af POE spec in mind, which has a much narrower tolerance - certainly nowhere near 72V.
Worth checking boards specs, and the actual supplies you are connecting to in order to avoid blue smoke -
Regards
Sorry to revive this ancient thread, but I am interested in a working solution to power Mikrotik routers (RB450G or RB2011) from telecom -48V. Thanks!