IEC TR 61341:2010 - Measurement Method for Centre Beam Intensity & Beam Angle of Reflector Lamps
Overview
IEC TR 61341:2010 is a crucial technical report published by the International Electrotechnical Commission (IEC), detailing standardized methods for measuring and specifying the centre beam intensity and beam angle(s) of reflector lamps. This method applies to a broad range of lamps used for general lighting, including incandescent, tungsten halogen, gas-discharge, and LED-based reflector lamps. It excludes special-purpose lamps such as projection lamps. This second edition supersedes the 1994 version, reflecting advancements particularly in LED lamp technologies.
The report aims to establish a consistent, repeatable method that supports accurate classification and comparison of reflector lamps based on their photometric properties. It is especially important for manufacturers, testing laboratories, and lighting designers focused on performance characterization and quality assurance of reflector lamps.
Key Topics
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Measurement Scope & Applicability
- Applies to incandescent, tungsten halogen, gas-discharge, and LED-based reflector lamps for general lighting
- Excludes special-purpose lamps like projection lamps
- Methods focus on design testing and photometric characterization, not on individual lamp assessment
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Core Terms and Definitions
- Optical Beam Axis: The axis around which the luminous intensity distribution is symmetrical
- Centre Beam Intensity (Ic): Luminous intensity measured on the optical beam axis (in candela)
- Peak Intensity (Ip): Highest luminous intensity value regardless of axis
- Beam Angle: Angle between two points where luminous intensity drops to 50% of centre beam intensity
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Beam Pattern Classification
- Symmetrical (circular) beams
- Asymmetrical (oval or elliptical) beams, requiring multi-plane measurements
- Irregular beams with multiple peaks requiring more complex evaluation
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Measurement Conditions
- Lamp aging and stabilization protocols differ by lamp type (e.g., 1 hour for incandescent, 100 hours for gas-discharge)
- Precise control of electrical operating conditions within ±0.5% tolerance
- Temperature control for LED reflector lamps with thermal equilibrium requirement
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Test Setup & Procedure
- Use of a photometer bench or directional photometer with CIE photopic spectral correction
- Positioning detector at suitable distance following the inverse square law
- Measurements conducted by rotating lamp or photodetector to capture intensity distribution in key planes
- Reporting luminous intensity distribution when centre beam intensity is low (e.g., “butterfly” beams)
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Technical Updates for LED Lamps
- Extended scope to accommodate LED reflector lamps
- Inclusion of measurement conditions to address LED-specific characteristics
- Added figures clarifying relationships between beam axes and intensities
Applications
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Lighting Design and Specification
- Enables designers to select reflector lamps with suitable beam angles and intensities for various applications such as retail lighting, architectural accentuation, and general illumination.
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Lamp Manufacturing and Quality Control
- Supports manufacturers in consistency testing and compliance with performance standards.
- Assists in classifying lamps by beam angle groups for cataloging and marketing.
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Standardized Testing Laboratories
- Provides a uniform measurement method to deliver reliable data for product claims, certification, and third-party verification.
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Energy Efficiency and Performance Reporting
- Accurate photometric measurements aid in evaluating energy-efficient lamps (including LEDs) under real-world conditions.
Related Standards
- CIE Technical Report No. 43 – Offers complementary information on photometric characteristics for floodlight luminaires, enhancing the understanding of beam performance.
- IEC 60081 series – Deals with performance and safety tests for various lamps, possibly including incandescent and halogen lamps.
- Relevant IEC Photometry Standards – Related photometric measurement and classification standards complement the test methods provided in IEC TR 61341.
The IEC TR 61341:2010 technical report is essential for professionals working with reflector lamps, enabling consistent measurement and clear communication of key photometric parameters like centre beam intensity and beam angles. Its inclusion of LED lamp requirements ensures its relevance in modern lighting technology landscapes. For the latest edition, updates, and service information, consult the IEC webstore or contact your national IEC committee.
Keywords: IEC TR 61341, centre beam intensity, beam angle, reflector lamps, incandescent lamps, tungsten halogen lamps, gas-discharge lamps, LED reflector lamps, photometric measurement, lighting standards, IEC standards.