Community discussions

MikroTik App
 
lucasimo88
just joined
Topic Author
Posts: 10
Joined: Fri Apr 06, 2018 8:43 pm

Positive ground system

Sat Oct 09, 2021 7:00 pm

Are mikrotik devices compatible with the 24v "positive ground system", or is there a risk of a short circuit?
 
ConnyMercier
Forum Veteran
Forum Veteran
Posts: 723
Joined: Tue Dec 17, 2019 1:08 pm

Re: Positive ground system  [SOLVED]

Sat Oct 09, 2021 7:07 pm

Following Mikrotik-Devices have optional -48V DC telecom Options.
CCR2004-1G-12S+2XS
CRS326-24S+2Q+RM
CCR1072

https://mikrotik.com/products/group/accessories
 
mada3k
Long time Member
Long time Member
Posts: 682
Joined: Mon Jul 13, 2015 10:53 am
Location: Sweden

Re: Positive ground system

Mon Oct 11, 2021 10:55 am

RB1100AHx4 has -48V support as well.
 
fermevc
just joined
Posts: 7
Joined: Thu Nov 09, 2017 7:27 pm

Re: Positive ground system

Tue Mar 07, 2023 10:26 am

Sorry to revive old thread, but I was looking for LAN switch that can operate in "positive ground" environment.
We have a couple of devices designed to operate in "positive ground" environment. ( - power terminal is isolated from chassis and ground) and we need to wire their LAN ports for remote management.
I've looked at RB1100AHx4 datasheet and there is indeed option to power it with DC voltage.
I need a little bit more info about the following statement from datasheet: 20 V - 57 V (-48 V supported).
I don't have RB at hand to measure if (-) terminal is isolated from chassis and ground or not.
Can someone please confirm that RB1100AHx4 can be powered via (-48 VDC positive ground) and that its chassis can be safely / properly grounded together with existing equipment?
Thanks in advance!
 
User avatar
rextended
Forum Guru
Forum Guru
Posts: 11967
Joined: Tue Feb 25, 2014 12:49 pm
Location: Italy
Contact:

Re: Positive ground system

Tue Mar 07, 2023 10:37 am

If it says on the site, and there's clearly a separate connector, it's true.
I don't think they would have left it written for years if it was wrong...
 
jebz
Member
Member
Posts: 366
Joined: Sun May 01, 2011 12:03 pm
Location: Australia

Re: Positive ground system

Sat Mar 11, 2023 4:18 am

I've looked at RB1100AHx4 datasheet and there is indeed option to power it with DC voltage.
I need a little bit more info about the following statement from datasheet: 20 V - 57 V (-48 V supported).
.
I think this image on the product page should assist in confirming the DC input is isolated -
.
Image
.
 
fermevc
just joined
Posts: 7
Joined: Thu Nov 09, 2017 7:27 pm

Re: Positive ground system

Sat Mar 11, 2023 5:23 pm

Thanks for the replies!
If I get a chance, I'll take one unit for testing/measurements, and will report the results here.
 
marekm
Member
Member
Posts: 379
Joined: Tue Feb 01, 2011 11:27 pm

Re: Positive ground system

Sun Mar 12, 2023 6:09 am

I can confirm RB1100AHx4 works fine with -48V DC power. Better not mix that with PoE-in on ether13 though, CRS328-24P trying to power up (when already powered by -48V DC) reports a short circuit. The same DC/DC converter is probably used by both the DC terminal blocks and PoE-in. Two 230V AC inputs are also available and work as redundant with DC.
 
fermevc
just joined
Posts: 7
Joined: Thu Nov 09, 2017 7:27 pm

Re: Positive ground system

Thu Mar 16, 2023 7:57 pm

I can confirm RB1100AHx4 works fine with -48V DC power. Better not mix that with PoE-in on ether13 though, CRS328-24P trying to power up (when already powered by -48V DC) reports a short circuit. The same DC/DC converter is probably used by both the DC terminal blocks and PoE-in. Two 230V AC inputs are also available and work as redundant with DC.
Thank you for the confirmation!
I wasn't planning to use PoE-in.
I just need to power RB using existing DC PSU which has positive grounded, and the question was:
Is it safe to ground RB1100AHx4 chassis to existing grounding bar?

Who is online

Users browsing this forum: lurker888 and 25 guests