Even a brief power outage can shut a server down abruptly, corrupt data and cut off the office network. A UPS (Uninterruptible Power Supply) protects equipment from these situations. But in our consultations with clients, we often see that choosing a UPS for servers takes more than looking at the capacity figure. Here is what the Techarg team takes into account when recommending the right UPS for servers and office network equipment.
Understanding VA and Watts in a UPS for Servers
UPS capacity is usually stated in two units:
- VA (volt-amperes): apparent power, the number often shown prominently in the product name.
- Watts: real power, the load the UPS can actually support.
What matters most is watts. The ratio of watts to VA is called the power factor. A 1,000 VA UPS with a power factor of 0.9 can support a load of up to 900 watts. That is why, when preparing a recommendation, our team always works from the wattage in the specifications rather than the VA figure in the product name.
UPS Types for Servers and Networks
| Type | How it works | Best for |
|---|---|---|
| Offline/standby | Switches to battery when the power fails | Individual PCs, light equipment |
| Line-interactive | Regulates voltage and switches to battery during an outage | Switches, routers, office PCs, CCTV NVRs |
| Online double-conversion | Equipment always receives clean power from the inverter, with no transfer gap | Servers, storage and critical equipment |
For servers and equipment that must run 24 hours a day, we recommend an online UPS because there is no gap when power switches to battery, which makes it the safest option for critical equipment.
How to Calculate UPS Capacity for Servers
During a consultation, our team calculates UPS capacity in these steps:
- Listing all the equipment that will be connected: servers, storage, switches, routers, firewalls and NVRs.
- Finding the power consumption (watts) of each device from its specifications, then adding them up.
- Adding a reserve of about 20–30% so the UPS does not run at its limit and still has room for additional equipment.
Example:
| Device | Power |
|---|---|
| Server | 450 W |
| NAS storage | 80 W |
| PoE switch | 150 W |
| Firewall and router | 40 W |
| Total | 720 W |
| Total + 25% reserve | 900 W |
In this example, the UPS capacity we would recommend is at least about 900 watts. These figures are only an illustration; in practice, our calculations always use the actual power consumption of the client's equipment.
How Much UPS Backup Time Is Needed?
Backup time depends on battery capacity and the size of the load. That is why the first thing we ask clients about is the purpose of the UPS:
- Enough for a safe shutdown (a few minutes): a UPS with internal batteries is usually sufficient, combined with software that shuts the server down automatically.
- Keep operating during the outage: this calls for additional external batteries or a generator, with the UPS bridging the gap while the generator starts.
Server UPS Maintenance Tips
From our team's experience in the field, a well-maintained UPS is far more dependable when it is actually needed. What we usually recommend:
- Regular UPS testing with a simulated outage.
- Battery replacement as recommended by the manufacturer, usually every few years.
- Keeping the UPS in a cool room, because heat shortens battery life.
- Connecting the UPS to the server via a data or network cable so it can trigger an automatic shutdown.
Conclusion
In every UPS recommendation, our team works from power in watts, adds a capacity reserve, and prioritizes an online UPS for servers and critical equipment. From the start, we also map out with the client whether the UPS is only for a safe shutdown or for keeping operations running.
Techarg supplies UPS units from brands such as Eaton and Schneider Electric as part of our IT hardware procurement service. Tell us about your needs, and the Techarg team is ready to provide consultation and a solution, including a calculation of the UPS requirements for your office. Contact us.