GB/T 45321-2025 Measuring method for electric and photometric parameters of filament light sources for power-driven vehicles
1 Scope
This document specifies the measurement principles, instrument and equipment, measurement conditions, measurement steps and data processing, and test report for the electric parameters, total flux, and chromaticity coordinates of filament light sources for power-driven vehicles.
This document applies to filament light sources used in power-driven vehicle road lighting and light signal devices and systems (hereinafter referred to as "light sources"), with reference also applicable to filament light sources for other road vehicles.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 2900.65 Electrotechnical terminology - lighting
GB/T 26178 The measurement of luminous flux
GB/T 43081-2023 Lamps and light sources for road vehicles - Dimensional, electrical and luminous requirements
JJG 247-2008 Standard incandescent lamp for total luminous flux
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 2900.65 and GB/T 26178 and the following apply.
3.1
filament light sources
a light source where the sole element that produces and emits light when powered is one or more filaments
3.2
test voltage
U
voltage applied to the base end of a light source for testing its photoelectric performance
Note: The unit of the test voltage is Volt (V).
3.3
total flux (of a light source)
?
cumulative flux within a 4 πsr solid angle
Note: The unit of total flux is lumen (lm).
[Source: GB/T 2900.65-2023, 845-29-046]
3.4
standard lamp
filament light sources intended for use as a reference in photometric or spectral radiometric measurements, with values traceable to primary measurement standards
Note: In this document, it refers to a standard lamp for total flux or color temperature, used for calibrating the test systems for total flux and chromaticity coordinates.
[Source: GB/T 2900.65-2023, 845-27-095, modified]
3.5
ageing (of a light source)
preprocessing stage before acquiring the initial values of the light source
[Source: GB/T 2900.65-2023, 845-27-108]
4 Principles
4.1 Electric parameters
The measurement of filament light sources for power-driven vehicles uses direct current (DC) power supply. The current is preferably measured through I-V conversion using a DC standard resistor and a DC digital voltmeter, with the measurement principle shown in Figure 1. Alternatively, a DC digital ammeter may be used for current measurement, with the measurement principle shown in Figure 2.
Figure 1 Schematic diagram of electric parameters measurement
(I-V Conversion method for current measurement)
Figure 2 Schematic diagram of electric parameters measurement
(DC ammeter method for current measurement)
4.2 Total flux
The total flux of a light source is measured using an integrating sphere, with both photometric and spectroscopic methods available.
The standard lamp and the tested light source are placed at the same position inside the integrating sphere. The total flux of the tested light source is calculated based on the indirectly measured illuminance or relative spectral power on the inner surface of the integrating sphere.
The measurement systems are shown in Figure 3 and Figure 4.
Figure 3 Schematic diagram of total flux measurement system (photometric method)
Figure 4 Schematic diagram of total flux measurement system (spectroscopic method)
4.3 Chromaticity coordinates
The measurement of chromaticity coordinates is conducted in a darkroom or light-tight box using a comparative measurement method. The standard lamp and the tested light source are placed at the same position inside the darkroom or light-tight box. The relative spectral power distributions of both are measured separately. Based on the CIE 1931 standard colorimetric system (XYZ), the tristimulus values X, Y, Z, and the chromaticity coordinates x, y of the tested light source are calculated. The measurement system is shown in Figure 5.
Figure 5 Schematic diagram of chromaticity coordinates measurement system
Contents
Foreword I
1 Scope
2 Normative references
3 Terms and definitions
4 Principles
4.1 Electric parameters
4.2 Total flux
4.3 Chromaticity coordinates
5 Instruments and equipment
5.1 Electric parameters
5.2 Total flux
5.3 Chromaticity coordinates
5.4 Traceability of instrumentation and equipment
6 Measurement conditions
6.1 Working environment
6.2 Aging
6.3 Ignition point location and direction
6.4 Stability
6.5 Voltage and current
7 Measurement steps and data processing
7.1 Preheating of measurement equipment
7.2 Electric parameter measurement
7.3 Total flux measurement
7.4 Chromaticity coordinates measurement
8 Test report
Annex A (Informative) Ignition direction of light source inside the integrating sphere
Annex B (Informative) Typical examples of power-on for light source and monitoring contacts for lamp terminal voltage
Annex C (Normative) Measuring method for light source absorption correction factor
