All this state-of-the-art equipment (PoE Switches, Routers, Wi-Fi 7 Access Points, Security Cameras) we have installed in our cabin has one common, huge vulnerability: It is completely dependent on power.
A simple power outage from the PPC, and your "smart" home is "blinded" and "deaf" instantly. Cameras don't work (since they draw power from the Switch), you don't have internet (since the Router shuts down), and home servers like NAS are at risk of losing data from the sudden shutdown.
This is where the Rack's guardian angel comes into play: the UPS (Uninterruptible Power Supply). Let's look at why not just any UPS will do the job, the differences between Rackmount and Tower, and how to correctly calculate the power you need.
Many people think that a UPS is just a big battery that keeps machines running when the power goes out. In fact, its most important role is to purify the current.
The mains voltage is never a constant 230V. It constantly makes brownouts or spikes. The sensitive power supplies of IT equipment are unimaginably strained by these fluctuations. A good UPS has AVR (Automatic Voltage Regulation) technology: It works like a "filter" that smooths out current irregularities, providing your expensive equipment with absolutely clean and stable voltage, extending its life.
When you go to buy UPS, you will find two completely different plans:
They are the classic rectangular UPS that we usually put under computer desks. Pros: They are much cheaper than their Rackmount counterparts. Cons: They don't have "ears" to screw into the 19 inch rails. If you want to put a Tower UPS inside the Rack, you need to buy a heavy-duty metal rack and rest it on it. It takes up huge, unused space (often 4U or 5U) and the cables coming out of the back look extremely ugly.
They are designed specifically for cabins. They have the standard width of 19 inches and height usually 1U, 2U or 3U. Pros: They integrate perfectly into the cabin, screw onto the rails, have LCD screens on the front and ensure perfect cable management and airflow. Cons: They are considerably more expensive and require racks with sufficient depth (at least 600mm or 800mm depending on the VA).
UPSs are divided into three categories based on how they manage power:
How big a UPS do you need? UPSs are measured in Volt-Amperes (VA), but your machines consume Watts (W). Their relationship is not 1 to 1. Depending on the Power Factor of the UPS, usually Watts is about 60% to 90% of VA. For example, a 1000VA UPS can usually handle a maximum of 600W with 700W of net load.
Your Calculation: Add up the maximum consumption (in Watts) of your equipment. (eg PoE Switch 150W + Router 15W + NVR Recorder 50W + NAS 40W = 255 Watts).
Note on Autonomy: The purpose of UPS is not to give you 8 hours of internet. Its purpose is to keep the system alive for 15-30 minutes (so that the micro-interruptions pass) and, if the interruption is prolonged, to instruct (via USB or network) your Server (NAS) to do a Safe Shutdown so that the hard drives do not fail.
Multiply the sum by 1.5 to have enough margin so that the UPS is not running at 100% of its load. So 255W x 1.5 = ~380W. A 750VA or 1000VA UPS will comfortably cover you.
Rackmount UPSs have heavy duty lead acid (SLA) batteries inside. A 2U UPS can weigh from 20 to 35 kg!
The UPS ALWAYS goes into the lowest point of the cabinet (1U or 2U from the floor). If you put it up, you change the center of gravity of the Rack, which can become dangerously unstable and tip over.
NEVER hang a heavy UPS by only its front "ears" on the rails. The weight will bend the rack rails or break the aluminum frame of the UPS itself. Purchase and install the special "L-Rails" (side support rails) or a heavy-duty 4-point rack so that the UPS sits securely at its full depth.
UPS is the "insurance policy" of your entire network. A Rackmount, Line-Interactive UPS with "Pure Sine Wave", bolted with sturdy rails to the bottom of the cabinet, guarantees that micro-interruptions and power surges will never reach your sensitive equipment, ensuring the 24/7 operation of your smart building.
Next Step: We have everything set up perfectly. But, all this cabin with Switches, UPS and Servers has to go into a room. And if you make a mistake in choosing the room, living with the Rack will become a nightmare.
We move on to the next article of the guide: Electrical Provisions for a Home Server / NAS (Home Lab): In which room should the Rack go (cooling, noise and dedicated power line requirements).
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