Power Factor Correction in LED Street Lights - Why It Matters for India

Q: Do LED street lights below 25W need active PFC?

IS 16102 does not mandate APFC for luminaires below 25W - passive PFC is permitted. However, many quality manufacturers include APFC even in lower-wattage drivers because: it adds minimal cost at small sizes and provides better compliance across all installation scales. For procurement: specify PF ≥ 0.95 and THD ≤ 10% for all wattages, regardless of the IS 16102 exemption for smaller luminaires.

Q: Can you feel the difference between a light with PF 0.5 and PF 0.97?

The light output looks identical - PF has no effect on brightness. The difference is entirely in the electrical supply side: the PF 0.5 driver draws twice as much current from the cable and transformer for the same light output. This extra current heats cables and transformers. In a large installation, it is visible on the electricity bill as higher reactive power charges for commercial and industrial consumers.

Q: Is there an easy way to measure power factor on a street light in the field?

Yes. A basic plug-in power analyser (₹500–₹1,500, available online) measures watts, VA, PF, and sometimes THD simultaneously. Plug the LED driver into the analyser and read the PF directly. Professional clamp-type power quality analysers give more accurate readings and can measure PF on an installed circuit without disconnection. For field verification during project commissioning, a plug-in analyser on a sample of 5% of lights is a practical quality check.

Power Factor Correction in LED Street Lights - Why It Matters for India

Power factor correction (PFC) is a circuit technology built into LED drivers that actively manages how current is drawn from the grid. Understanding it explains why quality LED drivers cost more - and why cheap drivers cause problems in large street light installations.

By Xera Tech Team · Updated 12 Jun 2026 · 4 sections

Passive vs Active PFC

Passive PFC: uses a large filter capacitor or inductor at the driver input to smooth the current waveform. Achieves PF of 0.85–0.92. Low cost. Does not fully eliminate harmonics. Adequate for small installations (a few dozen lights). Active PFC (APFC): uses a boost converter circuit that shapes the input current to be sinusoidal and in phase with the voltage - actively mimicking a pure resistive load. Achieves PF of 0.95–0.99. Significantly reduces harmonic distortion (THD <10%). Required for IS 16102 compliance for luminaires above 25W. All quality LED street light drivers above 25W must have Active PFC.

Why APFC Matters for Indian Grid Infrastructure

India's distribution transformers are sized for apparent power (kVA), not real power (kW). With low PF loads: a 100 kVA transformer can only supply 50–60 kW of useful power - the rest is reactive power that heats the transformer without doing work. In streets with 100 × 40W LED lights with PF 0.5: apparent load = 100 × 40W ÷ 0.5 = 8,000 VA = 8 kVA. With APFC (PF 0.97): apparent load = 100 × 40W ÷ 0.97 = 4,123 VA = 4.1 kVA. The APFC system needs only half the transformer and cable capacity - halving infrastructure cost. For large municipal systems with 10,000+ lights: the difference between PF 0.5 and PF 0.97 is the equivalent of needing 2× fewer distribution transformers.

Verifying APFC in Purchased LED Drivers

Look for on the driver specification: PF ≥ 0.95 (implies APFC). Explicitly stated 'Active PFC' or 'APFC'. THD ≤ 10% - only achievable with APFC. The ERDA or NABL test report measures PF and THD - these values confirm APFC performance under real test conditions. A product claiming PF 0.99 without an independent test report should be treated with scepticism - this is a common marketing exaggeration for cheap drivers. The IS 16102 test at ERDA or a NABL lab is the only authoritative verification.

Frequently Asked Questions