ErP Directive (EU) 2019/2020 Detailed Explanation of Light Source Functional Requirements - Displacement Factor (DF) Testing with PM310H

The ErP Directive (EU) 2019/2020 and Energy Label Directive (EU) 2019/2015 have been officially implemented. Displacement Factor (DF) is a new requirement, and many friends don't know how to test DF. Below, we will provide a brief introduction to the DF concept and testing methods, hoping to help friends solve the DF testing problem.

I. What is Displacement Factor (DF)?

The above figure showing the definition of DF (Displacement Factor) is a screenshot from (EU) 2019/2020, Page 15.

Displacement Factor (DF) is also cosϕ, which is the cosine of the phase angle between the fundamental current and fundamental voltage. DF is one of the important parameters for measuring the electrical performance of LED light sources.

II. What are the DF Requirements in the ErP Directive?

The above figure showing DF (Displacement Factor) requirements for LED and OLED light sources is a screenshot from (EU) 2019/2020, Page 22.

For light sources of different power, the DF requirements are different. Lamps with power less than or equal to 5W have no DF requirements; 5W to 10W require DF greater than or equal to 0.5; 10W to 25W require DF greater than 0.7; above 25W require DF greater than or equal to 0.9. Therefore, accurate DF testing is crucial for product compliance.

III. How to Test Displacement Factor (DF)?

1) Using Electrical Parameter Measurement Instruments That Can Directly Read DF

a) Using Yokogawa WT210

You can access the following interface by pressing keys to directly read DF (Displacement Factor). The WT210 is a commonly used power analyzer that can measure various electrical parameters including DF.

b) Using Hangzhou YIMING Technology Co., Ltd. PM310H Power Meter

The PM310H is a professional digital power meter that uses a large LCD screen display, which can display voltage, current, power, power factor PF, displacement factor DF, voltage and current total harmonic distortion, voltage and current crest factor and other parameters on one screen, making reading very convenient. The PM310H power meter is particularly suitable for DF testing of LED light sources, and can quickly and accurately measure DF values. Using PM310H for DF testing is simple to operate and provides reliable results.

2) Manual Calculation of Displacement Factor DF Through PF and Harmonic Content

If you have a power meter that can measure harmonics, and currently have no plans to purchase a new digital power meter (such as PM310H); then you need to work a bit harder and can calculate DF yourself using the method introduced below.

According to the formula introduced in Annex D of IEC62612-2013, you can calculate the Displacement Factor DF:

We get the DF calculation formula:

Where λ is the power factor, which can be directly obtained from general digital power meters (such as PM310H). Through the above formula, you can calculate the DF value, thereby determining whether the product meets the ErP Directive requirements for DF.