Advantages of DC

[petecarlson]

A little off topic, but since the DC switch will be able to take ~9-48V, and is smaller then a full 19" rack, I'm thinking of building mini DC sites with two AF24s or EQ and could use a smaller/cheaper 24V rectifier system and a smaller enclosure instead of a full rack. Does anyone have suggestions for a managed rectifier system that could be mounted in a smaller enclosure with a DC WISP switch? Just want to be able to monitor battery condition and perhaps do scheduled battery testing.

[sirhc]

By the way it is 9-60V INPUT but they are tuned to work best (most efficient) with 24V sites.

Our DC switches will monitor DC INPUT and CURRENT DRAW so you know what your batteries are putting out and what you are consuming.

On the flip side you can see which radios/devices draw the most current as we monitor that to on the switch side.

By using an SNMP monitoring system you will be able tell how often you're charging the batteries as you will see an uptick in the INPUT voltage when the charger is engaged.

Maybe down the road we could have the switch put a log entry in the switch log when it detects charging and when it detect charging has stopped as there will be a sudden drop in the INPUT voltage.

[cbl]

Our DC switches will monitor DC INPUT and CURRENT DRAW so you know what your batteries are putting out and what you are consuming.

Does the mini currently let you monitor DC input via the barrel connector?

[Dave]

yes

[petecarlson]

Anyone have any thoughts on using a meanwell DR-UPS40 for a mini pop with a Netonix DC switch:
http://www.meanwell.com/webapp/product/ ... d=dr-ups40

Seems like a nice cheap way to get battery backup on an AF24 or two. No temp compensation though.

[LRL]

We usually use the Tripp lite APS750's for our AC sites and we've used a couple of APS1250s as well.

We run a tiny two rack data center using an APSX6048. It runs a cisco blade chassis, two nexus switches, an EMC VNX, and a few misc servers. Our load is about 5k watts.

The nice thing about the tripplite inverter charges is the ability to give yourself as little or as much backup time as you want. The above mentioned data center can run for 36-40 hours on batteries alone. Beyond that we use a manual generator if it comes to it.

IMO, if you've got AC use it and back it up.

[rkelly1]

Chris - When your unit failed, did it continue passing through AC or completely cut off power?

[sirhc]

The "one" that failed was a LARGE 30 or 50 AMP unit and I am not for sure as this was at least 3 years ago but I think when it failed no AC passed through, DEAD

THis was my OLD Fiber POP with Level 3 which has since be decommissioned as a major POP but the cabinet and the replacement unit is still there working fine I think.

[bmv]

Great topic.

We had started off with standard 1000VA APC UPS systems at our POPs, but in a power cut, they were only providing about 4 hours of runtime at the site at best. They were low cost and simply to fit, plus with Mikrotik routers you can monitor using the serial cable.
We then started to design and create our own DC systems, first 24V and now 12V. However they are expensive, there are lots of components and batteries/DC-DC transformers seem to die or have problems, and they take time to build. We were also limited to using Toughswitches as they were easier to DC than other switches (before the Netonix DC switches have arrived).

We then have started to go back to AC!

The latest creation is a customised version of the Tripplite - however with our system our POP is running off the inverter 24x7, so inefficient and potentially will decrease the lifetime compared to the Tripplite which is mains passthrough and 20ms transfer on power failure.
For our critical POP sites, we have a combination of 2 x inverters, APC ATS transfer bar to provider redundancy in case either inverter fails, and a bank of 12V batteries in parallel with a 100A charger. This is costing £1000 ($1500+) though!

We are monitoring all our DC/AC backup sites with SiteMonitors to know battery charge levels and mains power status.

Now that we're aware that the Tripplite exists, this will massively simplify our set up.

All our sites are on-grid, so the hassle of DCing components is big, plus there is a huge cost to this.
All we want is a 1-1.5 day runtime system in case there is a power failure. We can always hotswap batteries or hook up a generator in extended power outages.
We're drawing no more than 100W at each POP and mostly <50W.
I think that AC battery systems, even with the inefficiency of DC-AC-DC when on the inverters is a price worth paying.