UPS Sizing

UPS sizing from connected critical loads

UPS capacity depends on the actual critical load, not a rough estimate. Model your critical loads in ekx and the UPS kVA requirement calculates directly from the connected equipment.

What you get

Critical load summary

Total critical load calculated from the devices actually connected to the UPS in your model.

kVA requirement

UPS kVA sized from connected load including power factor and derating considerations.

Fault current impact

UPS fault current contribution included in the short circuit analysis.

Voltage at critical loads

Bus voltages at critical loads calculated via load flow to verify adequate supply.

System integration

UPS is part of the one-line — not a standalone calculation disconnected from the system.

Upstream sizing

UPS input circuit and upstream protection sized based on UPS input current requirements.

UPS sizing in the context of the electrical system

A UPS doesn't exist in isolation. It has an input circuit, a bypass, a battery, and critical loads. ekx models it all in the same one-line diagram.

  • Critical loads connected to UPS in the model — kVA calculates automatically
  • UPS input circuit and upstream protection sized accordingly
  • Fault current contribution from UPS included in analysis
  • Voltage at critical loads verified under normal and emergency conditions

Start free. Upgrade when you need more.

Free tier includes 1 project with up to 2 buses. Paid plans start at $27/month for consultants and $149/month for unlimited access.

View All Plans

Frequently asked questions

How does it determine UPS size?

UPS kVA is calculated from the total connected critical load, including power factor and a typical design margin. You select from standard UPS sizes.

Does it model bypass operation?

The UPS can be modeled as a source in the system. Operation under different supply scenarios can be evaluated.

Is battery runtime calculated?

ekx calculates the kVA requirement. Battery runtime is a function of the UPS manufacturer's specific battery configuration and should be confirmed with the supplier.

Can I model redundant UPS?

Yes. Multiple UPS units can be modeled in the one-line diagram with appropriate distribution configurations.

Size your UPS from actual critical loads.

kVA from connected load, not a spreadsheet estimate.

Start Free