Input Power Factor, Output Rating and Efficiency: Read All Three

Put each number on the correct side

At the input, true power factor relates active power to apparent power for the defined measurement condition. In a single-phase case using consistent values, PF = P/(Vrms × Irms). With distorted waveforms, displacement angle alone does not describe true power factor. For three-phase systems, the applicable total measurement method and loading conditions also matter.

At the output, rated kW divided by rated kVA describes the declared active-to-apparent capacity relationship. It is a rating relationship, not a measurement of every connected load’s actual power factor. The load still has its own W, VA, waveform and operating behavior.

Efficiency relates active output power to active input power across the defined boundary. State the mode, load point and battery condition so that the numbers refer to the same energy path. Battery charging introduces stored energy as well as losses, which requires care in interpreting an AC-input-to-AC-output comparison.

Read one manufacturer example without merging its fields

Eaton’s 93E G2 datasheet lists input power factor of 0.99 and an output rating relationship of 0.9, with efficiency stated separately by mode. Its 100 kVA example is rated at 90 kW. These values can coexist because they answer different questions; they are not conflicting versions of one specification.

The same datasheet also gives a permitted load power-factor range separately from the output rating. That distinction is important: a nominal capacity ratio and a permitted load characteristic do not necessarily describe the same boundary.

This is an example from the named Eaton product. For a Highidea selection, request the corresponding fields for the exact configuration and operating conditions rather than transferring those numbers to another range.

Use a three-boundary quotation card

Complete each row independently before combining the results. A blank input-demand field cannot be filled with the output kW rating simply because both use watts.

Follow a hypothetical calculation through the boundaries

Assume a purely illustrative steady AC-to-AC case with 9 kW delivered to the load, efficiency of 0.90 and input PF of 0.99. Assume no net energy is being stored in or supplied by the battery, and use consistent measurement boundaries. The active input is 9/0.90 = 10 kW; apparent input is 10/0.99, approximately 10.10 kVA.

Now change only input PF to 0.90 while keeping the same assumed active input and efficiency. Apparent input becomes approximately 11.11 kVA. Active conversion loss remains 1 kW in this simplified example. Improving input PF changes the apparent-input relationship here; it does not erase the assumed conversion loss.

These are hypothetical arithmetic values, not Highidea specifications or a complete generator-sizing method. The example deliberately keeps output capacity separate: an actual UPS must still have the permitted W and VA capability for the connected load.

Avoid three purchasing mistakes

First, a high input PF does not mean conversion is lossless. Second, a high output kW/kVA rating does not establish the input PF at every load. Third, neither field replaces the other information needed for source compatibility, including relevant current distortion and transient behavior.

Legrand’s UPSaver datasheet lists input PF at different load levels, illustrating why a single headline number may not cover the operating range. Compare data at the state your project will use rather than ranking unrelated peak values.

Discuss the complete task with Highidea

Our rack online ET1-3KR and three-phase 33ET configurations serve different load arrangements. Provide Highidea with the source, load W and VA, expected load range, operating modes and recharge requirement. Request separate input, output and efficiency information for the proposed configuration.

Use the W and VA guide for load sizing and the mode-matched efficiency guide for the energy comparison. Keeping these tasks connected makes the quotation more useful without compressing three different boundaries into one score.

Primary references

• Eaton: 93E G2 datasheet.
• Legrand: UPSaver datasheet.