Question 1

How are lumens measured?

Accepted Answer

Lumen is a unit of measurement of the total amount of visible light emitted by a source, called the total luminous flux. The industry uses two main types of equipment to measure lumens: integrating spheres and goniophotometers. An integrating sphere is a hollow sphere with the interior surface coated with a highly reflective white coating. If the light source is within the sphere all the light rays are reflected many times from the inner surface and are thoroughly and evenly diffused. The photodetector measures the homogenized light signal and the calibration software calculates the total lumens. The test speed of this method is fast, and it is widely used in the rapid luminous flux test of LED light sources and small lighting fixtures. A goniophotometer works on a different testing principle, namely rotating the luminaire or moving the detector to measure the luminous intensity at a very large number of angular points in space in three dimensions. The instrument sums (mathematically) the luminous intensities in all directions to determine the total number of lumens. In addition to luminous flux, it can also output photometric data such as luminous intensity tables, light distribution curves, and beam angles. The LM-79 testing mentioned in the main text relies on this type of instrument.

Question 2

What is the purpose of the LM-79 report?

Accepted Answer

The LM-79 report (Now is called an LM-79-19 report) is an official test report issued by a laboratory that details the electrical, photometric and colorimetric performance of a complete set of LED luminaires. It is of critical importance, in the opinion of ZGSM. Many engineering projects require this report as mandatory documentation. Indeed, the key metrics used to evaluate luminaires in these projects are precisely power, luminous flux, luminous efficacy, light distribution curves and color parameters. The Illuminating Engineering Society (IES) developed the LM-79 standard to provide a uniform and repeatable method for testing LED light sources and luminaires.

Question 3

What’s LM-79 and LM-80?

Accepted Answer

LM-79 and LM-80 are industry norms for testing and rating LED lighting products, developed by the Illuminating Engineering Society (IES).

LM-79 is a standard method for testing fully assembled LED fixtures, treating the assembled fixture as one system to be tested. Test parameters: Total luminous flux (lm) Input power (W) Luminous efficacy Color Rendering Index (CRI) Correlated Color Temperature (CCT) Light distribution. It is mainly used to verify the initial performance of finished luminaires and is also required for certifications such as ENERGY STAR.

The LM-80 is intended for components such as LED packages, LED arrays and modules, not for testing complete luminaires. It is tested for lumen maintenance (light decay after long-term use) and color parameter drift under high temperature aging conditions for at least 6000hrs.

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Why is an LM-79-19 report required for photometric & chromaticity parameters?

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LED Street Light

High Mast Light

Led Flood Light

Solar Flood Light

LED High Bay Light

LED Tunnel Light

LED Garden Light

Led Bollard Light

Solar Street Light

LED Traffic Light

LED Canopy Light

Lighting Accessories

Smart Systems

Simulation Design

Smart Financing