Radiation Tolerant LED Luminaire
Following on from work done on a radiation resistant power supply for
emergency lights, a new
design has been developed to cope with the higher power demands of
conventional lighting in radioactive environments.
The LED luminaire is designed to be equivalent to the 36W T8 fluorescent
tube with the following performance objectives:
- Smaller physical size than an equivalent T8 luminaire to facilitate retro-fit
- Equivalent or higher light output (>2500lm)
- CRI >= 72
- Lamp Life > 50,000 hours to 50% failures
Research basis
The development of radiation hard lighting for the CERN accelerator complex started in 2009 with some initial tests on emergency luminaires. Since then the growing trend towards LED and the increasing emphasis on energy efficiency in EU directives has accelerated the obsolescence of conventional T8 fluorescent luminaires with wirewound ballasts (which, by virtue of the lack of electronic components are intrinsically very radiation hard). As a result CERN has been developing modifications to conventional LED luminaire designs which allow operation in the radioactive environment found in the accelerator tunnels.
A summary of the work on emergency lighting can be found here: Radiation Hardening of LED Luminaires for Accelerator Tunnels
Radiation testing of white power LEDs is detailed here: Modelling of proton irradiated GaN-based high-power white light-emitting diodes
More recent testing of optical materials, SiC diodes and GaN transistors is awaiting publication.
Functional specifications for electronic components
Technical Specification:
Variant 1 - High Radiation areas - Power Supply Module
Variant 1 electrical schematic
- Three-phase rectifier topology
- Output voltage: 538 V rms (ripple 300 Hz)
- 6x SiC (silicon carbide) Schottky diodes ST STPSC10H12G-TR
- Maximum current: 10 A
- Maximum blocking voltage: 1200 V
- Diodes radiation tested in IRRAD, up to 2×10^14 p/cm2.
- Limited voltage increase (~10%) at 1 A after the highest fluence (53 kGy, i.e. >53 years in the typical SPS radiation environment).
- Input Voltage: 400V AC RMS, 3 Phase
- Voltage Tolerance: +/-10%
- Input Frequency: 50Hz
- Frequency Tolerance: +/- 0.5Hz
- Maximum electrical power: 50W (measured at input terminals)
- Earthing Regime: TN
- Filters to be implemented in future versions on both AC and DC sides
- Relevant standards to be observed: IEC 61000-3-2, EN 55015, EN 50082-1, EN 50082-2
Variant 2 - Low & Moderate Radiation areas - Power Supply Module
Variant 2 electrical schematic
- Single-phase rectifier topology
- Output voltage: 170V rms
- 4x SiC (silicon carbide) Schottky diodes ST STPSC10H12G-TR
- 1x SiC MOSFET transistors WOLFSPEED (CREE) C2M0080120D
- 3x SiC MOSFET transistors WOLFSPEED (CREE) C3M0280090D
- Maximum current:
- Maximum blocking voltage: 1200 V
- Diodes radiation tested in IRRAD, up to 2×10^14 p/cm2.
- MOSFETs to be radiation tested in IRRAD soon.
- LED string current is controlled below 300mA
- Input Voltage: 230V AC RMS, between phase and neutral
- Voltage Tolerance: +/-10%
- Input Frequency: 50Hz
- Frequency Tolerance: +/- 0.5Hz
- Maximum electrical power: 115W (measured at input terminals)
- Earthing Regime: TN
- Filters to be implemented in future versions on both AC and DC sides
- Relevant standards to be observed: IEC 61000-3-2, EN 55015, EN 50082-1, EN 50082-2
Variant 3 - High Radiation areas - Linear Power Supply Module
Variant 3 electrical schematic
Variant 3 bill of materials
- Input Voltage: 230V AC RMS, between phase and neutral
- Single-phase bridge rectifier topology
- Output voltage: 320V DC
- 4x SiC (silicon carbide) Schottky diodes ST STPSC10H12G-TR
- Maximum blocking voltage: 1200 V
- Diodes radiation tested in IRRAD, up to 2×10^14 p/cm2.
- 2x GaN Gate Injection Transistors (Panasonic PGA26E019BA / PGA26E07BA)
- GaN Gate Injection Transistors irradiation results (IRRAD) to be released soon.
- LED string current is controlled below 400mA
- Voltage Tolerance: +/-10%
- Input Frequency: 50Hz
- Frequency Tolerance: +/- 0.5Hz
- Maximum electrical power: TBC W (measured at input terminals)
- Earthing Regime: TN
- Filters to be implemented in future versions on both AC and DC sides
- Relevant standards to be observed: IEC 61000-3-2, EN 55015, EN 50082-1, EN 50082-2
LED module for Variants 1 and 2 (3 units per luminaire in High Radiation areas, 1 unit per luminaire otherwise)
- 70x LED Osram Oslon Square GW CSSRM2.PM connected in series
- Maximum DC current: 1.8 A
- Average DC current in our luminaire (~80 mA)
- Typical voltage drop on LED at 80 mA: 2.7 V
- Luminous flux (per LED) at 80 mA: ~40 lm
- Luminous flux (per board) at 80 mA: ~2800 lm
- Tested against radiation in IRRAD, up to 2×10^14 p/cm2.
- 50% reduction in light output: ~10 kGy (>10 years in typical SPS radiation environment)
LED module for Variant 3 (1 unit per luminaire)
- 100x LED Osram Oslon Square GW CSSRM2.PM connected in series
- Average DC current in our luminaire (~100 mA)
- Typical voltage drop on LED at 100 mA: 2.7 V
- Luminous flux (per LED) at 100 mA: ~50 lm
- Luminous flux (per board) at 100 mA: ~5000 lm
- Tested against radiation in IRRAD, up to 2×10^14 p/cm2.
- 50% reduction in light output: ~10 kGy (>10 years in typical SPS radiation environment)
The three variants are proposed for the dual purpose of having a mixture of technologies and circuit topologies as an insurance against unforeseen failure modes. Lighting installations at CERN normally consist of 3 phase circuits, however conventional T8 luminaires are only connected between phase and neutral. The adoption of a 3 phase solution is therefore compatible with existing installation practices.
The design specifically excludes a transformer in order to minimise activation of the luminaire.
Spice simulations are provided for both variants of the luminaire electronics model.
General specifications for the luminaire construction
Project information
The design files are in LTSpice format, including the schematic and simulated electrical performance. You will need LTSpice to open the individual designs, and in some cases additional component libraries from the component manufacturers will be required.
- Variant 1 design files (zip file)
- Variant 2 design files (zip file)
- Variant 3 design files (zip file)
Contacts
Commercial producers
- Luminaires based on this design are not yet in production
Project Development
- James Devine - CERN - General question about project
- Alessandro Floriduz - CERN - Fellow (2016-2018)
Project Status
Date | Event |
02-10-2017 | Completion of irradiation test campaign for LED and SIC diodes |
29-01-2018 | Successful circuit test of Variant 1 design |
07-06-2018 | Successful circuit test of Variant 2 design |
14-09-2018 | Successful circuit test of Variant 3 design |
J Devine - 19 November 2018