24V Capacity on WS-24-400B

[bchur83]

I am running a WS-24-400B at my main core tower site that feeds all other sites. We have been doing some upgrades lately to Backhauls and Sectors moving from some old UBNT M5 gear to AF-5X-HD BackHauls and R5AC Gen2 APs.

After upgrading 4 sectors and 2 backhauls, I started getting random reboots of other AF5X units on the tower, not the new ones I had just installed. It was completely random, one would lock up and show no ethernet connection but was drawing power. After about 15min it would connect back up and another would go down. This kept repeating for about an hour. I then got to thinking about the bigger picture since it was randomly switching between 3 of my most loaded backhauls that were rebooting. Low Power issue... ?

I got to thinking about an article I read before about the WS12 models having a limited 24V PSU output to something like 108 watts without a modification to the internal PSU. This got me to take a look at the Switch power and it shows about 130w currently across the entire switch with about 500Mb/s traffic passing. All of the radios are running either 24V or 24VH and I remember a while back that some of the older AF5X units couldn't run 48V but newer ones could. So I switched the 2 newest AF-5X HD units to 48V. Boom, the rebooting stopped on the other radios. I then got to looking at the older AF5X units and I think I can switch one more over to 48V otherwise the others are in the MAC address range that will only support up to 24V.

I know someone will bring it up that the AF5x is designed to run on 4 pair power, but this hasn't been an issue at all for over 3yrs running some of them on just the normal 24V and not 24VH. Most of the AF5X radios are drawing about 10-11W so they are not over drawing on the 2 pairs.

So my question is, what is the capacity of the 24V PSU in the WS-24 series switches, since it sounds like on the 12 port models this could be an issue, does it affect the 24 port models? Is the 24V on split over 2 separate banks of 12 ports or is it a total capacity of the entire switch? As of right now, like i stated before, I am only using about 130W of power on the entire switch but most of that is 24V, so do I need a different switch? Add a 2nd one to take some of the load off?

[sirhc]

You do realize that you can power AFX radios (all except the first few hundred AF5X units made) with 24V, 24VH, 48V, and 48VH.

I would use 48V or 48VH to power AFX radios which would ease the demands on the boards 24V power supply.

Read this post on AFX radio powering options: https://forum.netonix.com/viewtopic.php?f=6&t=1215#p9040All newer WS-12 boards are rated to 160+/- watts of 24V

All WS-24 and WS-26 boards have (2) 24V power supplies, 1 for ports 1-12 and 1 for ports 13-24 each rated at 160+/- watts.

[bchur83]

I do know "most" AF5X's can run on up to 48v. Unfortunately I have at least 3 on this tower that are before they switched to the 48v power option. I have already switched 3 of the newest AF5X units to 48v but the older units don't allow it based on their MAC addresses. The other radios I have on the tower are mostly a mix of R5AC Gen2 or PBE-5AC which all need 24v.

Since the early WS12 switches had an issue with the 24V not having full capacity on earlier revisions (108W vs 160W without the PSU mod?), does the earlier WS24 suffer this as well? Ours is a Board Revision B and we have had it for over 4yrs. It just seems like the issue started when we exceeded around 100W @ 24v on the first 12ports since that is where most of our 24v Backhauls are plugged into the switch. I can certainly move some ports around to distribute the load between the 2 PSUs but I was just curious what the limits are for the capacity on various models of switches.

The WS-24-400B is rated for 400W and from what you are saying it only has a "max" capacity of 320W @ 24V if evenly split across the 2 banks of ports and that is at full load. So lets assume in reality you shouldn't load the 24V beyond 130W for each bank? In a perfect world we all would have an even split of devices at 24v and 48v but that isn't always the case. I think there should be some sort of section in the datasheets that states these limited capacities at certain voltages. It is relevant information that people should know to be able to design their networks in the most efficient manner for PoE power.

[sirhc]

No the 24V issue never affected the WS-24 models, different boards differnt designs.

We advertise the switches with the power supply rating (total capable watts).

I agree maybe I should adjust the spec sheet to make this more clear however we assume people will be running some AF or MIMOSA radios as that was our big selling point in the beginning that we were the only POE switch capable of powering AF radios. Besides people never read the spec sheet (most) or the forums.

To be kind "most" people will not listen to me on grounding and dangers of ground current. I also had a guy send me a WS-12-250-DC switch RMA with a 1A 12V wall plug power adapter hard wired to the unit wondering why it keeps rebooting....

You would be suprised at what we deal with, people trying to power a WS-12-250-DC 200 feet up a tower with 14 AWG wire or even worse an Ethernet cable with 2 pair for negative and 2 pair for positive again wondering why they have issues.


So if you assume say with a WS-12-250-AC

4 ports are capable of 48VH and lets say someone powers 4 AF radios that is 200 watts right there.

But lets say common
2 AF radios = 100 watts
10 airMAX AC radios with a peak of 15 watts average 10 watts = 100 watts average of 24V and the 24V power supply is rated to 160+/- watts

Or another common
1 AF radios = 50 watts
11 airMAX AC radios with a peak of 15 watts average 10 watts = 110 watts average of 24V and the 24V power supply is rated to 160+/- watts

Still plenty of head room there.

The problem was in the beginning we made a design decision to limit 24V to 106 watts but at the time average airMAX watts was 6 watts per UBNT spec sheet even though it spikes to 12-15 watts under heavy transmit loads. UBNT still only lists "average" watts not peak transmit watts.

But in the beginning we assumed at least 2 AF radios and 1 port to router so maybe 9 ports with average draw of 6 watts = 54 watts but even under all radios transmitting which should not happen that is 12 watts x 9 = 108 watts.

[bchur83]

Can you tell me if the WS-24-400B, even early versions (2014? 2015?) have the full 2x 160W 24V Power Supplies? I have moved over a few radios to 48V that could run 48V and moved a couple other 24V radios over to the 2nd bank of ports and this seems to have solved my random cycling issue at this site.

It appears to me to be a power load from the start and I am just curious if the 24port had the full 160W available to each bank of ports from the start since the 12port switches seem to have only had the 108W capacity before the 2017 revision?

[sirhc]

THE ONLY MODELS EVER TO NOT HAVE 160+/- WATTS PER 12 PORTS WAS THE WS-12-250-AC, WS-12-250-DC, WS-12-400-AC, WS-12-DC

The WS-24-400A and WS-24-400B all had 160+/- watts per 12 port bank of 24V POE.

Now with that in mind some of those units are 4+ years old now