FAQ: Material related questionsQ: Stainless steel is the preferred material for conventional lighting in NPPs. Why do you promote aluminium housing?A: Because stainless steel has extremely poor thermal conductivity. Heat is number one killer (beside the radiation, of course) of any electronics and drastically reduces the lifetime of the product. Keeping operational temperature as low as possible has always been our main design goal.Q: What is thermal conductivity?A: Thermal conductivity is the ability of the material to conduct heat. It is measured in W/mK. Here are some thermal conductivities in W/mK:Air: 0.02Wood: 0.04Concrete: 0.8Stainless steel: 16Iron: 80Aluminium: 200Copper: 400Diamond: 1000From the table above it can be seen, that the stainless steel has poor ability to conduct heat. In fact, the ability of stainless steel to conduct heat is one of the worst in metals. This is the obvious reason, why we promote aluminium for LED Luminaires.Q: Did you try to make the same Luminaire in stainless steel/aluminium/copper housing?A: Yes, we tried. We tested the same Luminaire housing made out of copper, aluminium and stainless steel. Stainless steel has by far the worst thermal performance.Q: You can compensate bad thermal performance of the stainless steel by adding more cooling fins, right?A: Wrong. You can add stainless steel cooling fins to infinity without results. The only effect is heavy, bulky product, without proper cooling.Q: What is emissivity of the material?A: Emissivity is the surface property of the material. It shows the ability of the material to exchange heat energy with the surrounding media. Any glossy finish of the heat sink material has bad emissivity and therefore slow exchange of the heat energy with the surrounding air. An aluminium foil (glossy finish) has emissivity coefficient of 0.04, while anodized aluminium has the emissivity of 0.8. In both cases the same material regarding thermal conductivity, but anodized one has 20 times better emissivity, i.e. exchange of the heat with the surrounding media.Q: Aluminium is not allowed in areas where hydrogen generation might be the problem. How do you solve this problem?A: For applications inside the RB we are offering Stainless Steel version of the Luminaires. Due to very poor thermal performance of the Stainless Steel, the maximum allowed ambient operating temperature is limited to 50 oC (Aluminium version 80 oC). The material of the housing however does not have any impact on LOCA compatibility.
FAQ: Radiation related questionsQ: Do you test your products with radiation source, or you just compile public documents describing radiation hardness of electronics/materials?A: We always test our products and never assume anything. All our products have full nuclear qualification and tests, performed by third party certified laboratories.Q: Which part of your Luminaire is tested to radiation?A: Each and every part of our product is tested with gamma and neutrons. This includes all mechanical parts (housing, screws, optics, diffuser, gaskets, coatings, connectors, wires etc.) and all electronic parts including LEDs and complete LED control gear (driver).Q: Where do you test your products and components?A: All our products are tested inside the core of General Atomics TRIGA Mk II nuclear research reactor in Jožef Stefan Institute, Reactor Infrastructure Centre in Ljubljana, Slovenia, EU. In case of gamma irradiation, the nuclear reactor is shut down, without presence of neutrons. In case of neutron irradiation the research reactor is operating normally. Q: Which part of LED Luminaire is the most problematic one regarding radiation?A: LED control gear (driver) is by far the most problematic part of any LED Luminaire. Q: Your electronics is not affected by gamma and neutron irradiation. Why?A: Every electronics is affected by the radiation, including ours. We achieved world’s best radiation hardness in LED lighting industry with careful selection of components and circuit topology, cancelling the effects of radiation damage.Q: Many producers of LED Luminaires are testing just LEDs to gamma. Is this correct?A: No. The LED itself is relative insensitive to radiation, opposed to power electronics which might be up to 1000 times (three magnitudes of order) more sensitive. Testing LEDs only and assuming the Luminaire has the same radiation hardness as LEDs, is false.Q: Do you irradiate your electronics biased?A: Of course. Our electronics (complete functional PCB) is irradiated biased, i.e. up and running at full power before, during and after the test. Irradiation of non powered or unbiased electronics, or even components alone, not installed on PCB, gives wrong, misleading result - a magnitude better then biased. Q: Do you use Cobalt for gamma tests?A: No. For gamma and for neutron irradiations we use TRIGA Mk II Nuclear Research Reactor. Nuclear reactor has similar gamma spectrum to NPPs and better mimics real world situation inside the containment.Q: Is your LED driver sensitive to the dose rate?A: No. LED control gear is tested with the dose rates between 250 and 25.000 Gy/hour without any influence to operation of the Luminaire.Q: Your H series should have “World’s best radiation tolerance in LED lighting”. Is this correct?A: Yes, it is. We specify our products with radiation tolerance of up to 500 kGy. In fact we tested our electronic inside the core of the TRIGA MkII nuclear research reactor to more than 1 MGy (0.1 Grad). And the electronics is still functional. Q: Do you use shielding techniques?A: No, there are no radiation shields inside the Luminaire. Radiation hardness is achieved by design.Q: Are your radiation test reports available to the public?A: All test reports are available to qualified customers.
FAQ: Photometry related questionsQ: Are your photometric data simulated/calculated or measured?A: Our Luminaire photometric properties are measured in the Europe’s leading laboratories and not just calculated from LED vendor data sheets.Q: What is the output of the photometric measurements in the photometric lab?A: Beside standard test report, the output of the photometry are photometric files used in simulation software. Eulumdat .ldt and IESNA .ies files.Q: Do your Lumen/Watt specification represent LED efficacy?A: No, never. Our efficacy in lm/W is measured in the photometric lab and represent overall Luminaire efficacy - from the wall outlet to the luminous flux out of the product.Q: Your lm/W specification is relatively low in comparison to other LED Lighting vendors. Why?A: Correct. The numbers are lower then most others, because we are not specifying LED efficacy as Luminarie efficacy. There is big difference between this two numbers. LED efficacy is the number taken out of the LEDs manufacturer data sheet, measured in the ideal conditions. Luminaire efficacy takes into account also all optical and electrical losses, which lovers overall Luminaire efficacy. Optical losses are due to losses in optics, Luminaire housing, protective glass or diffuser. The best designs with optics or diffuser have at least 20% of losses. If we add at least 10% of losses in the LED driver, we can estimate overall losses to minimum 30%. In practice this value can be much higher. If Luminarie incorporates high performance LED with 200 lm/W and if we take into equation optical end electrical losses, then overall Luminaire efficacy is less than 140 lm/W.Q: Why should I check which efficacy is specified in the Luminaire data sheet - LED efficacy or Luminaire efficacy?A: Let me explain this with simple example. If we take high performance LED with data sheet efficacy of 200 lm/W and put this LED into the black box, then the overall efficacy of this “Luminaire” will be exactly 0 lm/W. Which specification for this “Luminaire” is now correct 200 lm/W or 0 lm/W?Q: How to avoid wrong and misleading figures in the Luminaire data sheets?A: Simple. Request photometric test report of the Luminaire.Q: Are your photometric test reports available to the public?A: All test reports are available to qualified customers.
FAQ: Reliability and lifetime related questionsQ: What is MTBF?A: Mean Time Between Failures or MTBF represents the statistical approximation of how long a number of units should operate before a failure can be expected. It is expressed in hours and does not represent how long the unit will last. For instance. If we test 1.000 units for 1.000 hours and 1 failure occurs, the MTBF value would be 1 million hours. This does not mean, that the unit will operate for 1 million hours or 114 years. If 1 million units are operating with calculated MTBF of 1 million, a failure can be expected every hour.Q: Who performed MTBF calculation for you?A: We contracted our MTBF calculation with Israeli company A.L.D. , the leading consulting firm and software house in the field of Reliability Engineering and Analysis, Safety Analysis and Safety Management, Quality Engineering and Quality Assurance.Q: Which method do A.L.D. use for MTBF calculation?A: There are many methods and standards to choose from for MTBF calculation. We decide to perform MTBF calculation according to US military specification MIL-HDBK-217F Notice 2, one of the most frequently used and recognized standards in the industry.Q: What is the relation between MTBF and lifetime?A: The confusion between these two parameters is the most common confusion in the reliability theory. However, there is some mathematical way to use MTBF to roughly expect a lifetime. For our products the calculated lifetime with 95 % of confidence is about 22 years operating 24/7/365 - i.e. continuous operation. Due to exponential nature of mathematical formula, for 100 % of confidence the calculated lifetime is zero hours, or with 0 % confidence, the lifetime is indefinite.Q: 100.000 hours of lifetime is well known figure for LED lighting. Why are you complicating with calculations?A: 100.000 hours is the number you can find in any LED component data sheet. It is a pure theoretical figure and give us an idea how long a LED component (not a LED Luminarie) can last if it operates under ideal conditions. Conditions inside the LED Luminarie, where the LED component is operating, are far from ideal. The operating temperature (bad thermal design), current density (driving LED at maximum power), the technology and the quality of the LED component are all affecting real operating life, which can be much lower then 100.000 hours.Q: Does the LED Luminaire last as long as LEDs?A: Not at all. LED Luminaire has many other components too. The most problematic, and the most unreliable one, is LED control gear, sometimes called LED driver or ballast. By far the most unreliable components in any power electronics, are electrolytic capacitors and opto couplers. Our power supply does not use any of them. Just for comparison. The best electrolytic capacitors have lifetime expectancy of just few thousand hours at rated temperature. Should we expect, that the Luminaire itself will last for 100.000 hours? Probably not.Q: Finally, what is the lifetime of your Luminaire?A: A million dollar question. Statistically speaking, more than 22 years with the confidence level of 95 %. Also statistically, our Luminaire can fail in the first hour of operation or it can last forever. The probability of either is very low, but is possible.Q: Do you use third party LED driver?A: No. We are using only LED driver developed and produced in-house with all required nuclear qualifications.
H-100, 100 W, Ultra Rad Hard LED
Nuclear grade High-Bay LED Luminaire:•TID: 500 kGy (50 Mrad), tested/certified•Neutron fluence: 5×1014 n/cm2 1 MeV, tested/certified•IP68/69K, IK08, tested/certified•>160 lm/W overall efficacy, tested/certified •LOCA tested/certified•Seismic tested/certified•“All in one” solution, no external boxes•Stainless Steel housing, no plastic parts•100 % browning and shatter proof opticsDesigned for most demanding nuclear applications in the RB of the NPPs.
Generation IV, the Family of Ultra Rad Hard Nuclear Grade LED Luminaires
Beside the world’s highest tested and certified radiation tolerance of 500 kGy (50 Mrad), the latest generation also includes:•World's first and only LOCA tested and certified LED Lighting•World's first and only "all in one" solution, without external boxes mounted elsewhere•World's first and only "all in one" solution designed for in the air and under the water applicationsFour family members are available:H-100,100 W, >160 lm/W, 500 kGy TID, IP68/69K, IK08, LOCAL-100,100 W, >160 lm/W, 50 kGy TID, IP65, IK07H-50, 50 W, >170 lm/W, 500 kGy TID, IP68/69K, IK08L-50, 50 W, >160 lm/W, 50 kGy TID, IP65, IK07
L-100, 100 W, Rad Hard LED
Nuclear grade High-Bay LED Luminaire:•TID: 50 kGy (5 Mrad), tested/certified•Neutron fluence: 5×1013 n/cm2 1 MeV, tested/certified•IP65, IK07, tested/certified•>160 lm/W overall efficacy, tested/certified •16.500 lm, CRI 80, CCT 5000K•For high ambient temperatures up to 80 oC•“All in one” solution, no external boxes•Aluminium housing, anodized•100 % browning and shatter proof opticsDesigned for less demanding, cost sensitive nuclear applications.
H-50, 50 W, Ultra Rad Hard LED
Nuclear grade Low-Bay LED Luminaire:•TID: 500 kGy (50 Mrad), tested/certified•Neutron fluence: 5×1014 n/cm2 1 MeV, tested/certified•IP68/69K, IK08, tested/certified•>170 lm/W overall efficacy, tested/certified•8.500 lm, CRI 80, CCT 5000 K•“All in one” solution, no external boxes•Stainless Steel housing, no plastic parts•100 % browning and shatter proof opticsDesigned for demanding nuclear applications. Ideal for hot cell lighting.
L-50, 50 W, Rad Hard LED
Nuclear grade Low-Bay LED Luminaire:•TID: 50 kGy (5 Mrad), tested/certified•Neutron fluence: 5×1013 n/cm2 1 MeV, tested/certified•IP65, IK07, tested/certified•>160 lm/W overall efficacy, tested/certified•8.000 lm, CRI 80, CCT 5000K•For high ambient temperatures up to 80 oC•“All in one” solution, no external boxes•Aluminium housing, anodized•100 % browning and shatter proof opticsDesigned for less demanding, cost sensitive nuclear applications.
LOCA tested and certified
H series is world’s first and only LOCA (Loss Of Coolant Accident) tested and certified LED Luminaire.H series is designed for typical DBA (Design Basis Accident), where beside high radiation levels, high temperatures, hot steam, high pressure and chemical survivability are required.LOCA certification is a post Fukushima requirement and the ultimate test for any equipment mounted inside the Reactor Building of the typical NPP.The test was performed in UJV Rez Nuclear Institute, Czech Republic.
Seismic tested and certified
An earthquake is one of the most feared natural phenomena in any NPP. After the Fukushima disaster, all equipment installed inside the containment of the NPP, should have seismic certification.Our Luminaires were seismically tested in one of the Europe most advanced facility, the Military Institute for Ground Forces in Czech Republic.The test report is available on request.
Radiation tested and certified
Neutron and gamma irradiation tests were performed in General Dynamics / General Atomic TRIGA Mk II Nuclear Research Reactor in Jozef Stefan Institute, Ljubljana, Slovenia.Gamma spectrum of the research reactor mimics real life situation in the NPPs .Beside nuclear reactor irradiation, Cobalt irradiation test were performed in Rudjer Boskovic Institute, Zagreb, Croatia.Both Nuclear Reactor and Cobalt irradiations show world’s highest radiation tolerance in LED Lighting.
Photometric properties of the Luminaires were measured in Europe leading photometric laboratories, using latest photo goniometer instruments.Our experts can offer to the customer complete lighting design, using latest lighting design/simulation software.This is the fastest, easiest, most cost effective and by far most accurate approach to lighting without any guessing. Optical .ldt files for all our products are available on request.
Generation IV of our Ultra Rad-Hard LED Luminaires can be modified according to the customer specification.Possible modifications of the existing members of the family are:•custom holder,•the shape of the Luminaire base plate and•the type of optics.All other characteristics are not affected by the modification. All the documentation including certificates are the same as for the original, non modified version.
DITO is fully privately held company founded in 1992 by Srecko Bizjak B.Sc. (CEO) and Rafael Kitak B.Sc. (R&D). Both are exclusive owners of the company to this day.In 1995 we developed world’s first multichannel, studio grade, PC based, digital audio recorder DAR-20. In the year 2000 we bring to the telecommunication market our DSP based multichannel, multifunctional, fully programmable, 2 Mbit/E1 digital voice announcement system.In 2007 we developed TNS++, railway copper wire transmission system. TNS++ is still world’s unique product for multichannel DSP based, fully programmable, very high performance tone communication, over standard railway copper wire cables. The system is used for communication between relay based safety related railway equipment worldwide.In 2009 we started with LED Lighting development. First, with the street and heavy duty industrial lighting products. In 2013 we jumped to nuclear LED Lighting business.Our goal is to bring to the nuclear market world’s highest radiation hardness in the LED Lighting industry, world’s best LOCA scenario compatibility and world’s best “all in one” in the air and under the water LED lighting system.