Power Factor vs Efficiency in LED Power Supplies

Efficiency and power factor describe different things

Conversion efficiency is DC output power divided by real AC input power. At a hypothetical 90% efficiency, a supply delivering 90W to its load takes 100W of real input power. The 10W difference represents conversion losses inside the supply. Efficiency is therefore useful when comparing input demand and heat dissipation for a defined output load.

Power factor is real AC input power divided by apparent input power. Apparent power is RMS voltage multiplied by RMS current and is expressed in volt-amperes, or VA. A PF of 0.6 does not mean that only 60% of the incoming real power becomes useful DC output; that would confuse power factor with efficiency.

Active power factor correction, usually abbreviated PFC, addresses the AC input behaviour. It does not by itself establish a particular conversion efficiency, output rating or installation suitability.

Read the two entries separately in an LNS-P specification

The HYRiTE LNS-100P specification lists the LNS-12U100P at 12V, 8.33A and 99.96W, with 91% efficiency. Its LNS-24U100P counterpart is listed at 24V, 4.16A and 99.84W, with 93% efficiency. The PF entry is at least 0.9 at 230V AC and full load.

The same document identifies active PFC and states that unspecified measurements are made at 230V AC, rated load and 25°C ambient temperature. These are separate entries with defined conditions. Do not turn the 93% efficiency figure into a PF claim, or promise the full-load PF at every dimming level.

What changes when power factor changes?

To isolate the effect of PF, consider two hypothetical supplies each delivering 90W at 90% efficiency from 230V AC. Both take 100W of real input power. The values below are calculations using assumed operating points, not measured results for either HYRiTE model.

The higher-PF example draws less RMS current for the same real input power. It does not deliver more DC output in this comparison, and the assumed conversion loss remains 10W in both cases. This is why a purchaser should request efficiency and PF separately instead of using either as a general “energy saving” score.

Check load, voltage and starting current

A rated-load specification does not establish performance at a lightly loaded operating point. If a sign spends much of its time dimmed, give the supplier the expected load range and request matching PF and efficiency data. Also state the mains voltage: the LNS-P PF entry above explicitly names 230V AC.

Steady-state RMS current is different from inrush current at switch-on. Neither the worked example nor a high-PF label determines how many supplies can share a breaker. That decision needs the actual inrush behaviour, switching arrangement, protective-device characteristics and installation assessment. Keep this check separate from the steady-state calculation.

Turn the distinction into a clear purchasing requirement

Specify DC voltage, total load, expected input voltage, operating temperature and any required minimum PF at a stated load. Request efficiency at the same operating point. If dimming or standby operation matters, describe those conditions rather than relying only on a full-load headline value.

Browse the HYRiTE product series index and standard LNS-100V product page. For LNS-P specifications and project requirements, contact HYRiTE. The signage enquiry checklist helps organize the information needed for selection.