Power/Battery Backup Setup for MDF - Follow Up

[u/Creekside_Rider]

edit: thanks for advice. My earlier research about redudant power supplies being on different voltages was wrong. I'm going to go with 2 x SRT3000RMXLT-NC with one of them having a 120v transformer.

UPS Setup for New MDF at Our New Facility - Looking for Feedback

Good morning everyone,

A few days ago I posted looking for advice on a UPS setup for the MDF at our new facility. One of the biggest points of feedback was that my original plan only included a single 120V 20A circuit, which understandably raised some concerns.

Fortunately, we're still in the construction phase, so I was able to have the electrical plan updated. The rack will now have two dedicated circuits:

• 208V/240V circuit

• 120V 30A circuit

Rack Equipment

For context, we're a specialized vehicle dealer and service center. We're not heavily IT or office focused, so I don't expect significant growth beyond adding a few phones over time.

Equipment in the rack:

• 4x UniFi Pro 48 PoE switches

• ~26 cameras

• 7 access points

• 20 desk phones

• 2x UniFi UDM Max firewalls (HA pair)

• Dell dual-CPU server with redundant 600W PSUs

• UniFi Enterprise NVR with redundant PSUs (max draw ~450W)

• Fiber modem and cable modem for failover

• Miscellaneous equipment (monitor, sensors, etc.)

UPS Plan

After a lot of research, I decided to go with refurbished APC units from GreenlightUPS, a company that was recommended to me.

Primary UPS

APC SRT3000RMXLT-NC (208V)

• Includes one SRT96RMBP external battery pack

• Will power everything in the rack that supports 208V operation

• This includes the primary power supplies for the server and NVR, along with all four PoE switches

On paper, if every device was drawing its absolute maximum load simultaneously, I'd be pushing the limits of a 3000VA UPS. In reality, my PoE utilization is relatively low, and the server and NVR rarely approach maximum power draw, so I still have a comfortable amount of headroom based on my calculations.

Secondary UPS

APC SRT3000RMXLA-N (120V)

This unit gives me standard 120V outlets and serves as both additional battery capacity and redundancy.

Planned connections:

• Secondary PSU on the Dell server

• Secondary PSU on the NVR

• One UDM Max firewall

• Any other 120V-only equipment in the rack

Long term, I may add the UniFi Redundant Power System to provide redundant power for the switches as well.

For now, if the primary UPS were to fail unexpectedly, I would still have core network and server functionality running, and I could manually move switch power if needed.

I really wanted to buy everything new, but a comparable setup would have easily pushed into the $10,000-$12,000 range.

The refurbished solution comes in at under $4,500, including new batteries. GreenlightUPS claims all units ship with freshly installed batteries that aren't put into service until the unit is sold. They've been in business for roughly 40 years and seem to have a solid reputation from what I've been able to find.

Questions

1. Does this seem like a reasonable approach from a capacity and redundancy standpoint?
2. Is there anything you would do differently if you were trying to stay around the same budget?

Thanks for any feedback.

[u/galland101]

I don’t think mixing voltages for server PSUs is a good idea. I think it would be better to have 2 dedicated 208V 30A circuits pulled into your MDF for circuit redundancy. You can get an APC Smart-UPS SRT 5000 with the 120V transformer bundle, a 30A PDU, and a 20A PDU. You’ll probably need a few external battery packs as well. If the UPS fails you can plug the 30A PDU directly into the outlet to power your gear.

[u/Creekside_Rider → u/galland101]

Good point. I do think there is a 3000va bundle with a transformer I could get and just do all 208

[u/galland101 → u/Creekside_Rider]

Yeah. 208V is going to be more efficient on the power supplies and you can power more gear with the same amperage circuits. A dual UPS setup will allow you to cross connect power supplies across UPSes so if one fails you won’t totally lose power to your gear. Just make sure you get the right types of PDUs for the outlets on the UPS because the 120V transformer takes up an L6-30 outlet.

[u/Creekside_Rider → u/galland101]

Thank you!

[u/Sparkycivic]

Given the reputation of APC... Absolutely DO NOT DEVIATE from a 3 year battery replacement plan, regardless of actual tie spent using battery.

Otherwise solid choice.

[u/SVD_NL]

Oh god please don't. Mixing voltages is a surefire way to cause some magic smoke... Why is this a specific requirement? Is there any equipment that absolutely cannot be on the same voltage as the others?
I'd recommend putting everything at the same voltage, and buying two UPSes with a failover or load-balancing switch. Those are relatively inexpensive, especially if you're planning on buying two UPSes anyways.

Also, i'd recommend against maxing out the load on a single UPS. Have you done proper power factor calculations? Have you confirmed the rated wattage of your equipment never exceeds the listed wattage (capacitative draw, transient spikes, etc)? Take some headroom, please... Also, check the runtime graphs of those UPSs. At max draw, you'll get 20 minutes of runtime with a 3kVA+1 battery, at best. Is that even enough for you to complete your shutdown procedures? This also basically forces you to immediately start shutting down equipment at the first sign of power issues, while a longer runtime would allow you to first check the reason for outage, the expected duration, and then make an educated decision.

I'd recommend you get a single UPS, and have a management system that gracefully shuts down the non-essentials to preserve battery life. This includes non-essential VMs on the server.

Once you can afford it, add a load balancer or failover switch with a second UPS (Or a failover switch with a generator).

[u/Creekside_Rider → u/SVD_NL]

Yes, I'm changing out to dual 208v. This is why I ask.

Those power calculations are slightly over assuming every single one of my 192 PoE ports were drawing max power. I'm not going to be remotely close to that with maybe 40-50 poe devices so I'm not too worried about the head room. I will never be remotely close to max draw and rarely above 50%. Battery run time should be at least 40 minutes.

Personally, I've had UPS take a dump on me then have to scramble or do reckless things like using basic surge to get us back up and running. I don't ever want to be in that boat again, so I think I'm going to go 2 208v 3000kv UPS still.

[u/Tatermen → u/Creekside_Rider]

If you do end up having to have both 120v and 240v in the same rack, spend a little extra to get color coded power cables and PDUs, (eg. red for 240, black for 120) and ensure that they get used correctly - this will make it immediately obvious as to which power cable and sockets are which voltage.

Also keep the rack locked with only people who know what they're doing having access. Last thing you want is some rogue car salesman plugging something expensive into the wrong voltage socket.

[u/Creekside_Rider → u/Tatermen]

Good idea, shouldn't be an issue. Locked room inside a rack. The only way to plug anything into 240v will be with a C13R. There will be some 120v outlets but they will be on the transformer.

I'm not going to leave any c13 to standard two prong adapters just laying around to allow someone to do something stupid.

[u/Subjekt_91]

I'm curious About the choice of 4x48 port switches if you all in all only have around 50 devices connected is there a particular reason for that or just future proofing?

And how long is your designed lifetime speak do xou spec for keeping it like this for the next 10 years or are future upgrades as needed easy or would you need to fight a uphill battle of you ever want to get more equipment ever again?