Author Archives: Tero Nurmi

About Tero Nurmi

A man from the world of physics. Tero has a vast experience from working with laser technology. Currently Tero is the product manager for Arrant-Light Oy's aLED-modules and OLED-panels.

Microwave Sensors: How to Utilize Them in Lighting?

This blog post deals with microwave sensors. Especially how they are used with general lighting components to realize intelligent lighting systems. Some pictures enlighten the possibilities of microwave sensor technology better than hundreds of words.

Microwave Sensors

Microwave motion sensors operate in a different way that e.g. more commonly used passive infrared sensors. MW sensor sends out microwaves and analyzes the echo that comes back to the device.  If the movement changes the echo pattern the sensor will respond and switch the light on.

Microwave sensors have a consistent capability of detecting movement over all temperatures. PIR sensors’ detection sensitiveness might vary depending on the temperature. In addition, infrared sensors are vulnerable to dust and smoke and tend to have a shorter lifespan.

The lifetime of a microwave sensor is around 50.000 hours and our sensors are completely dust- and smoke-proof.

Example of a detection pattern when the sensor is mounted either on a wall or on the ceiling. Detection area can often be precisely set via dipswitches.

Microwave sensors can also detect movement through some non-metal materials such as glass and even thin walls. This gives more options for installing the sensor because it can be located out of sight or inside the luminaire.

Energy-saving In More Ways Than One

In addition to the traditional ON-OFF -control of a luminaire our sensors offer a wider selection of functions. You can also choose between 2-step and 3-step dimming. You can create larger networks of luminaires by utilizing RF communication between sensors to control several luminaires at once.

Some products have built-in daylight sensors, which enables you to fully take advantage of daylight and maintain sufficient light levels during dusk and dawn. This is called daylight harvesting.

Wikipedia states that several studies are implying to energy savings through daylight harvesting being around 20-60%. The greatest savings are achieved in rooms and areas where daylight has a significant impact on the lighting conditions through large windows for example.

In addition to energy savings, using these sensors also prolong the lifetime of your luminaires when luminaires are not on unless the light is actually needed.

Daylight sensor detects the level of ambient light and adjusts artificial light accordingly.

Endless Possibilities to Better Lighting Conditions

Correct lighting conditions make reading and writing more enjoyable, improves safety and can even have a positive effect on health. Where to use these sensors to get the best possible benefit out of them?

Some sensors are stand-alone models and can be connected to the LED driver. Other sensor products already include the driver. This gives you more options when you’re planning your lighting setup.

I have picked a few examples for you just to give you an idea of all the possibilities this kind of intelligent lighting control technology possesses.

Balcony: On/Off — Warehouse: 3-step dimming — Office: Daylight Harvesting

Restaurant: DALI LED Driver — Restroom: 3-step Dimming — Gas Station: Cluster Control & Daylight Harvesting

Conference Room: Cluster control — Underground Parking: 2-step Dimming — Stairwell: RF Wireless Control

As you can see, there are numerous function options and product combinations. To see a more detailed list of all the different types of sensor products in our range, take a look at our website.

To download a presentation on these sensor products, simply click the button below.

Download Here

How to Connect LED Modules into AC Network

In my earlier post I went through the procedure of how to physically connect a single LED component into an AC network. The connection was made between COB LED and the LED driver. When connecting LED modules (LED diodes assembled on the PCB board) you do it pretty much the same way with slight differences.

Connecting an SMD LED module into the AC network

As with a COB LED component, you will need a suitable driver for your module (see: how to choose a constant current LED driver).  You connect the positive terminals and the negative terminals of the LED driver and the LED module together to create a closed electrical circuit.

The difference to connecting a single LED component is that you may have to connect several LED modules into the same LED driver. In such case, you have to use series connection. This means that you still have to create a closed electrical circuit formed by the LED driver and these LED modules on the secondary side. You arrange the primary side like you would with single LED components. On the secondary size you connect the positive terminal of the first LED module (leftmost module in Figure 1) into the positive terminal of the LED driver. Then you connect the negative terminal of the last module (rightmost module in Figure 1) to the negative terminal of the LED driver. See Figure 1 below that shows all connections between the components.

Figure 1. Connection of LED modules into AC network through the driver.

How do you make other connections? Series connection means that you always connect the negative terminal of the previous array to the positive terminal of the following array in the chain. See again Figure 1. The output voltage of your LED driver defines how many LED modules you can drive with one driver. In case of Figure 1, one LED driver drives three LED modules. If voltage over LED module is for example 12V, the output voltage of the LED driver should exceed 36V. In the real world, you have to take into account tolerances. So in this case, 40V can be used as target for the driver maximum output voltage.

In the same way, you can connect multiple COB LEDs in series. This may be the case when you need vast amount of light.

How to actually do it?

As for physical connections of SMD LED modules, there are four options:

  1. PCB terminal block connectors
  2. Soldering
  3. Wire-to-board connectors
  4. Board-to-board connectors

PCB terminal block connectors are quite popular. They are soldered on the PCB board in the reflow process (in reflow oven) after the assembly process. You push the wires into those PCB terminal blocks in the same way as you would push the wires into the push-in terminals of solderless connectors in the single COB case.

Figure 2. PCB terminal block connector (2-pole)

Soldering is an option, if there are separate soldering pads reserved on the PCB to solder the wire(s) with tin. Soldering is usually a more cost effective option.

The numbers 3 and 4 are the special cases when you wish to interconnect two modules with each other. I’ll skip them for now and save them for later post.

If you’re interested in aLED’s new, improved LED modules, read more over here.

Feel free to drop a comment if you have questions on this topic.

How to Connect a Single LED Component into AC Network

I have two blog posts for you focused on how you connect COB LED components into the electrical network. I mean, when you have either a single COB LED or an LED module based on SMD LED components assembled on a PCB board.

Compared to traditional lighting, connecting LEDs to the electrical network is a whole new world. LEDs need direct current (DC) to light them, alternating current (AC) will not work. There are also AC modules available but those are not covered here.

In this post I will concentrate on connecting single COB LEDs. In case you are interested in connecting LED modules, I will write about that in my next post.

LED driver

You will need an LED driver, which is actually an AC/DC converter. It converts the AC voltage/current of the electrical network into the suitable DC voltage/current needed by the LED component. You will find the requirements of the LED from a datasheet provided by the manufacturer. If you need help in choosing a driver, you can read our guide.

Figure 1. Example of an AC/DC converter, LED driver. This one is from ELT with dipswitches, which means that you can choose the driving current.

Connecting COB LED into the AC network

In case of COB, you will have to create a closed electrical circuit so that the electrical current can flow through the LED component. A COB LED is basically a diode in its electrical nature: the current can flow only in a forward mode. This means that you must connect the positive (+) solder pad of the COB LED into the positive terminal of the LED driver. In the same way, you connect the negative (-) solder pad of the COB LED into the negative terminal of the LED driver. See the Figure 2 below.

 

This way, you create the closed electrical circuit that is needed to feed current through the LED so that it gives light. This closed electrical circuit formed by the LED driver and the COB LED is called the secondary side of the LED driver. LED driver feeds the power and current into the closed electrical circuit, and thus through COB LED, on the secondary side.

 

Figure 2. COB-AC Network

 

On the primary side, the LED driver gets electrical power from electrical network, AC network. The terminals of the LED driver on the primary side are called line and neutral. They are connected into the line and neutral connections of the AC network. If you have an LED driver with cables, they are usually blue (neutral) and brown (line). Some drivers also have a ground terminal, which is usually connected to the luminaire body with grounding wire. However, the closed electrical circuit is needed also on the primary side; between the network and the driver.

Usually, you will need to use some kind of terminal block to connect the driver into the electrical network on the primary side.

Picture of a terminal block

Figure 3. The example of terminal block to connect the LED driver into the electrical network.

Two options

Finally, as for physically connecting a COB LED into the LED driver, you have two ways to do it:

  1. solder the wires on the solder pads of the COB
  2. use solderless connectors.

In the first method, you manually solder the wire by using soldering iron with high temperature that melts the soldering material such as tin. After cooling, there is a joint between the wire and the COB solder pad. You need two wires, one for plus and one for minus solder pad.

In the second method, you use a solderless connector.

Figure 4. The solderless connector.

The solderless connector does the same effect as the soldered wire. You need the electrical connection also in this method, but you won’t need to solder the wire by melting tin. You just push the wire into the push-in terminals of the connector. Again, positive to positive and negative to negative terminal. They are marked on the connector. Basically these push-in terminals work with a combination of metal plates and springs that then make the connection to the solder pad of the COB LED.

The difference between these methods is, that unlike with soldered joints, in the solderless connector method the springs may loosen a bit over time and loss of contact may occur. Solderless connectors are generally thought to be more expensive than manual soldering.  

In my next post I will go through the steps for connecting LED modules.

Glass Lens vs. Silicone Lens in Street Light

What is the difference between a lens made from optical glass and the lens made from silicon, when used in street light application?

In this blog post, I will explain the pros and cons of both lenses. I will also use a case example to showcase the differences.

The Basics

First let me explain few basic terms related to optics in street light:

Light Pollution

Light that doesn’t go to desired direction and causes harm of anykind. It is wasted light, that isn’t used to its primary purpose. Light pollution can be divided to three different categories:

  • Glare

""9.0

Discomfort glare results in an instinctive desire to look away from a bright light source or difficulty in seeing a task. So as told by its name, discomfort glare causes discomfort.

  • Uplight
Light Pollution (Uplight/Skyglow)

Light Pollution (Uplight/Skyglow)

Uplight can be seen especially in cities: it makes sky glow and stars disappear.

  • Light tresspass
Light Pollution (Light trespass)

Light Pollution (Light trespass)

Light trespass is found in the vicinity of streets: it can prevent you from sleeping or disturb your garden lighting.

Optical glass

Pros:

  • Cheap to manufacture
  • Very high temperature range, sensitive also to stress

Cons:

    • Complex optical shapes can’t be done accurately or if the complex shapes are needed, it is expensive
    • Non-optimal light distribution in street light
    • Heavier than silicone (freight costs are more expensive)
    • Lower light transmission than in silicone lenses

 

Silicone

Pros:

  • Enables high precision manufacturing of complex optical shapes
  • High integration level in luminaire
  • Material weighs less than in case of glass lens

Cons:

  • Cost is higher than for glass lens

  • Lower temperature range
  • Lower fire rating

Glass Lens

Glass Lens Light Distribution in Street Light Application

Glass Lens Light Distribution in Street Light Application

In the image you can see the light distribution image taken from above. This application uses Glass lens.

      • Boom angle 15 deg
      • 10880 LED lm, eff 88%
      • Eav 9.0 lx (>9.0 lx)
      • Eav/Emin 2.2 (<4.0)
      • Lv max/Lav 0.3 (<0.4)

Silicone Lens

Silicone Lens (Stella DWC2) Light Distribution in Street Light Application

Silicone Lens (Stella DWC2) Light Distribution in Street Light Application

In the image you can see the light distribution image taken from above. This application uses Stella DWC2 Silicone lens.

      • Boom angle 10 deg
      • 8400 LED lm, eff 92%
      • Eav 9.0 lx (>9.0 lx)
      • Eav/Emin 2.3 (<4.0)
      • Lv max/Lav 0.3 (<0.4)

Results

Glass lens needs more lumens for the same application. In this case, around 20% more. This means that you generally speaking need more power to get the same amount of light out from the luminaire.

The reason behind the lumen need is the fact that glass lens generates more light pollution. You can see that the trespass light area is much larger in glass lens image (the red box). And on top of this, glass lens distributes light 10 meters away from road. In comparison, silicone lens only distributes 7 meters.

So I think I can end this blog post by stating that the silicone lens gives a lot of advantages over glass lens in street light application.

Vivid LEDs: Special Color Rendering With Spectrum Tuning

When we talk about color rendering, traditionally that conversation has been filled with CRIs and Ra-indexes. These traditional ways of telling how well certain light source represents sunlight have been criticised because they may not tell the whole truth.

In recent years, LED manufacturers have been trying to answer this criticism by creating different products. Terms like “premium white”, “crispy white”, “pearl white” and “vivid white” have come to LED markets.

Despite the different terms, they are all meant for the same purpose: To represent certain colors and make the lighting look better. I will be using term “Vivid” as it is the term Citizen Electronics uses. And to be honest, it describes the purpose of these LEDs quite well.

Color rendering

Color rendering means simply how well a white light source can show, or render, the true colors of different physical objects compared to sunlight. You know the effect when you buy a jacket in the clothes shop and it looks completely different in sunlight.

Colors are divided into 15 indexes (R1-R15). A general color rendering index (CRI or Ra-index) is defined as an average of the sum of first eight indexes (R1..R8). However, these first 8 indexes are rather less saturated colors, while indexes R9-R12 represent highly saturated colors (red, yellow, green, blue).

CRI 100 = Sunlight

For example, in grocery stores, a shopkeeper may want to highlight red color of meat or colors of vegetables. This means that the general color rendering index doesn’t really tell anything about the rendering capabilites of the light. In this case, high rendering index of some of R9-R12 indexes is necessary. It doesn’t matter how high the CRI is, R9-R12 can be anything.

CRI 83 (look at R9)

CRI 83 (look at R9)

The above image shows the index values of R1-R15. The CRI is 83, but look at the R9 value. Not very good.

So basically, the LED itself can have the CRI of 97 and you still have no idea how does it render red or green for example.

Vivid via Spectrum tuning

Vivid LEDs are made using spectrum tuning. In short, this means that the phosphorus of the LED has been modified. How it is modified, depends on the LED and the intended application. Note that spectrum tuning can be made also by using RGB-LEDs.

For example, Vivid White LED’s spectrum has been tuned so that it represents white and bright colors as well as possible. The colors are more saturated than under typical normal LED light.

Test report on Vivid White aLED Module

Test report on Vivid White aLED Module. Click the image to open it in new tab for better view.

These LEDs work very well for example, in clothing stores, where you have a lot of different colors that need to look good.

Here are two good principals when choosing LED:

  1. Think about your application, what colors do you want to highlight?
  2. Don’t stare at the CRI (unless you get a full report), it might not tell everything

Conclusion

Traditional way of thinking color rendering solely through the CRI should be updated. More importantly, you should know what you want to highlight and ask for a LED suited for your application.

Download More Information About Vivid

 

What is OLED in Lighting?

OLED means Organic Light Emitting Diode.  It works in similar way than (semiconductor) LED. Both need positive and negative charge carriers to generate electrical current and finally generate light.

It is a surface light source based on organic material layers. LED, on the other hand, is a point light source that is based on semiconductor materials. But the operation is based on the same principle.

OLED as Surface Light

OLED as Surface Light

The large-area LED modules, that are covered by opal diffuser, are basically similar light sources as OLED panels. Without this diffuser, these LED modules also are point light sources because of small SMD LED diodes they have on their surface.

OLED panels are surface light sources by nature. They give uniform light.

The benefits OLED:

  • Its light has spectral power distribution very close to sunlight.
  • Color rendering index (CRI) of 90.
  • Produces no glare
  • Produces very little heat(<35°C),
  • Doesn’t produce any UV and therefore it doesn’t cause blue light hazard risk.
  • Panels are thin and lightweight.
  • Simple light: panels don’t need many accessories unlike LED, such as heat sinks, diffusers, or other optics. It only needs the power source and the light source itself.

    Spectrum of OLED

    Spectrum of OLED

Structure of OLED

The OLED structure consists of layers. These layers have different purposes.

There are basically THREE different kinds of layers that have some purpose. Of course, you need anode and cathode terminals to bring electricity from outside world to the panel. As an example, LG Display uses Aluminium as cathode material and ITO (indium tin oxide) as their anode material.

  • Light generation layer: Emissive Layer (EML). Generates light.
  • Electrical current flow guidance: Electron Transport Layer (ETL), Hole Transport Layer (HTL) and Hole Injection Layer (HIL). These layers are used to transport charge carriers in optimal way to the light generation layer, EML. But also, they have to be optically suitable for light generated in the EML layer so that as much light as possible is extracted from the panel.
  • Third type of layer: Encapsulation. The encapsulation layer is used to protect inner optically active layers from any outside harm that could deteriorate the operation of the panel.

This kind of set of layers is called a stack.On top of the stack is the encapsulation layer.

OLED Structure

OLED Structure

For example, LG Display uses two-stack structure for 3000K and 4000K OLED panels and three-stack structure for 2700K panels. Because there are more stacks in 2700K version, the overall voltage over the panel is a bit higher.

Encapsulation

One major problem with the organic materials is that they are very sensitive to oxygen and moisture. This means that OLED panels need to be protected – as even a single water or oxygen molecule can harm the panel.

The encapsulation layer also protects from minor physical impacts. If this encapsulation layer deteriorates it will affect the optical layers. Usually strong glass is used for rigid OLED panels. But flexible panel is gaining more and more popularity. Flexible panels use plastic.

 

Drawbacks

The major drawbacks of OLED panels are:

  1. Easy to break

At the moment, most panels use glass substrates. These substrates are very fragile and are easy to break when not handled with care. This will improve in future as technology develops and plastic substrates will gradually replace glass.

  1. Cold endurance

You can’t use the panels in temperature of under 0 degrees of Celsius. This will obviously place some constraints for the use.

It is very probable that the cold endurance will get better in the future as the technology develops.

  1. Technological immaturity

OLED is still very young technology and it can’t produce very large amounts of light. It also loses to LED in luminous efficacy.

This will obviously improve in the future as manufacturers are investing in new product facilities.

Applications

As a surface-type lighting element, OLED can be used in different kinds of interior designs. It can give the background or accent/ambient lighting for example some artworks or other objects.

OLED as an Accent Light

OLED as an Accent Light

Basically, new application areas are up to you.

You can find and download ideas about OLED lighting from our website.

 

FAQ: OLED – Panels

From this post, you can find the most frequently asked questions related to OLED panels. The post will be updated in the future if new questions arise.

Q: What is OLED? Does it work in the same way as LED?

A: OLED means Organic Light Emitting Diode. It works in similar way than (semiconductor) LED. Both need positive and negative charge carriers to generate electrical current and finally generate light.

OLED Structure

Structure

You can read about the structure and tehnology of OLED from my other blog post.

Q: How OLED panel is attached on the surface/profile that is used in the luminaire?

A: The panel can be attached in many ways, but most common way  is to use adhesives. The screw connection is not recommended for panels.

Every panel manufacturer should have a list of adhesives that are not allowed with their products.

Q: How the to handle OLED panels?

A: You must handle them with care. At the moment most panels use glass substrates and because the panels are very thin, they break very easily. In the future, plastic substrates will replace the glass substrates. This will obviously decrease the risk of breaking the panel.

You can find more exact instructions on handling the panel from the datasheet of the panel.

Q: Can you bend the OLED panel because it is so thin?

Bendable OLED Panel in Luminaire

Bendable Panel in Luminaire

A: You can’t bend the glass substrate panels.

Plastic panels are ok to bend. There is a limited bending radius that can be found from the datasheet. Within that limit, you can bend the plastic panels almost endlessly.

Q: How you connect the OLED panels if you want to light many panels at time?

A: You can drive many panels by connecting them electrically in series. So you have the same current going through each panel and you get the same luminous output for each panel if they are the same products. Thus you can drive for example 4-panel luminaire with one driver as long as the voltage range of the driver allows you to do so.

Q: Which temperature range is allowed for OLED panels?

A: Basically, OLED lighting can be used only in indoor lighting at the moment. For example, LG Display informs in the datasheets of their panels, that operating temperature has to be over zero degrees of Celsius, and this applies also to storage temperature. Only transport temperature can be lower than zero degrees of Celsius, but only for a limited time.

Typical recommended operating temperature range is 0..40°C.

Q: What kind of new application can be done with OLED?

A: One interesting application is so-called transparent connection. In this case the panel is attached inside a glass plate. The current/power is then provided to the panel through metal mesh transparent conductive film.

OLED Transparent Connection

Transparent Connection

You can find and download ideas about OLED lighting from our website.

OLED Lighting Market to multiply by 15 in next five years – Are lighting manufacturers ready?

The world market for OLED Lighting will grow to 1.6 billion US Dollars in next five years. This year the market is estimated to be 135 million Dollars. This is according to UBI Research.

The situation is similar to LED market in 2007. When we introduced Citizen LED to our customers in 2007, many held a COB in their hand for the first time. Many were skeptical about the technology. But try to imagine the market without LEDs now.

Those who were brave and took the chance with LED, are now controlling the market. Although LEDs were expensive back then, the design work that was made before the prices dropped was priceless for many of our customers.

Flexible OLED lighting

Flexible OLED panel

Now we are presenting the first OLEDs for many of our customers. Many people are skeptical. They don’t believe that OLED will ever become mainstream. Some companies plan to skip OLED and other start designing luminaires with OLED.

Those that start now, are ahead when the market starts to grow.

New investments for OLED Lighting factory

LG Display announced in March that they are investing in a new OLED light panel manufacturing facility. The new facility will be the first 5th generation OLED light panel manufacturing plant in the world. It will be built in South Korea in the city of Gumi.

The initial capacity of the plant will be 15 000 glass substrates per month. This can be scaled up when the demand increases.

LG is expecting that the new plant will give it significant price competitiveness as well as more know-how and even better quality.

The new facility’s capacity will give LG flexibility in panel size. This means that LG Display will be able to manufacture panels of all sizes, including giant ones.

OLED panel is made up of layers of organic materials. It is self-illuminating and consumes less power and also emits lower heat than conventional lighting. OLED is environmentally friendly and is closest to natural light. Due to its ability to be thin and flexible, it is suitable for different applications and venues and could create new markets for lighting. You can read more about OLED Lighting panels from my blog post about OLED.

If you need any help in designing OLED lighting, contact me and we can start the design process together!

Source: http://www.lgdisplay.com/eng/prcenter/newsView?articleMgtNo=4981

FAQ: aLED Modules

Q:You have the driving current 700mA written in the datasheet of your LED module.  Can I use smaller driving current?

A:Yes, you can use smaller current. The current value 700mA mentioned in the module’s data sheet is so-called nominal/typical value that corresponds to the value Citizen announces for voltage and luminous flux (lumens) of the diode used in that LED module.

The minimum current is defined by the diode datasheet and in our 700mA modules the minimum current is 70mA. But you can also use the larger current. The maximum current is 1190mA. Please notice that you have to take care of cooling of the module in case that you use the maximum current. The warmer the module, the lower the lumen output and the shorter the lifetime.

CALC-0814 Absolute Maximum Ratings Found From the Datasheet

CALC-0814 Absolute Maximum Ratings Found From the Datasheet

Q: What is the IP classification of your aLED modules?

A: It is basically IP00, because if our LED arrays are not placed inside the luminaire, they are subject to dust and moisture. So if you need IP classification for your luminaire, please ensure that the luminaire casing has the desired IP classification.

Q: Ok, your aLED modules are classified as IP00, can they then be potted or protected from dust or moisture with some special coating?

A: Basically if you want to cover them with some coating or even pot them, you have to always contact the supplier of that coating or potting material to find out how it affects the LED components. Usually LED manufacturer gives some warranty for their products but this warranty applies only under certain pre-specified constraints or conditions.

Additionally, using coating may alter, and probably does so, optics of the LED components from the characteristics announced in the datasheet of the LED component manufacturer.

So basically you can use potting or special coating, but you should always check how the process affects the module.

Q: How the driving current affects the lifetime of LED module?

A: The lifetime estimations curves, lifetime hours versus temperature TC, are informed for the LED modules at their maximum rated current. That means that maximum condition is used and then lifetime hours are announced at different TC temperatures. The TC point is found in every LED module and is usually located near the soldering terminal, anode or cathode, of the LED diode located near the center of the module.

CALC-0814 Lifetime Estimation curves

CALC-0814 Lifetime Estimation curves

Higher current means higher Tc point temperature and therefore it means shorter lifetime. On the other hand, lower driving current means lower Tc point temperature and therefore longer lifetime.

Q: Are your modules MacAdam 3-step compliant?

A: Our aLED modules follow color consistency in MacAdam 3-step. This means that from production batch to production batch color coordinate values stay within the MacAdam 3-step ellipse. This means that our modules are MacAdam 3-step compliant.

Depending on the CCT, variation in Kelvins is different for MacAdam 3-step, being ±65K for 2700K and ±140K for 4000K.

For 5000K and 6500K our LED modules are only within ANSI binning, not within MacAdam 3-step.

Q: How many aLED modules  you can drive with one 50W/90W 700mA driver?

A: It depends on the module, of course. For the sake of an example lets look at CALC0814-M17W1.

First of all, as you can see from the module’s datasheet, the power is 700mAx24.16V = 16.9W. This is power when the module is driven with 700mA typical current. If you use one 90W driver, you can drive 5 module in series connection.

Let’s do still check calculation. As given by the module’s datasheet, the maximum voltage of the module is 26.4V if all LED diodes are at maximum value of voltage binning range. This is unlikely, but should be checked anyway. Total voltage of 5 modules in series is 5×26.4V = 132V. In our example case the LED driver’s maximum output voltage is 129V. However, the case that all 40 diodes in series connection would have 3.3V (maximum voltage of voltage binning range) is very unlikely. With typical rated value of 3.02V given in the diode’s datasheet, total voltage of 5 modules in series is 40×3.02V = 120.8V, which is within driver’s output voltage range.

So 4 modules is definitely ok. Probably you could drive five, but then we would need to check that they all are from the typical binning.

If you use 50W driver, you can safely drive only 2 arrays in series connection. In our example case the LED driver’s maximum output voltage is 72V. If you drive 3 arrays in series, even the typical voltage is 3×24.16V = 72.48V, which is too much for the driver.

Q: How do you calculate aLED module’s total voltage and total current.

A: We use the information of the diode and the information how many diodes there are in series and how many in parallel.

Circuit Schematics for CALC0814

Circuit Schematics for CALC0814

Let’s take CALC0814-M17W1 as an example. Numbers ‘08’ and ‘14’ refer to electrical configuration of the diodes in the module. First number, ‘08’, refers to how many LED diodes are in series between the + and – terminal of the array.  Second number, ‘14’, refers to how many LED diodes are parallel in one LED chain. In this example, there are 8 pcs of LED chains in series and 14 LED diodes connected in parallel in each LED chain.

Typical value for the diode is 50mA and therefore there is 700mA going through each chain (14x50mA). That gives the total current of the module. With this typical current of 50mA, the diode forward voltage is 3.02mA and there are 8 LED chain in series in this module. This means the typical total voltage of the module is 24.16V (8×3.02V).

Q: aLED modules have quick connectors. Can I use soldered wires instead of quick connectors?

A: Yes, you can. If there are no separate solder pads for soldering wires, you can use quick connector solder pads but in this case the connector is not assembled in the assembly process. In some aLED modules both options are possible simultaneously.

Please note, that with different connectors, the delivery time might be little longer.

If you have some other questions, that were not found in this list, please feel free to ask me. I will answer to you directly and add the general questions to this FAQ later.

Tero Nurmi
Product Manager
aLED Modules
tero.nurmi@light.fi

How Lifetime Affects the Energy Savings of a Luminaire

Generally, when selecting LED luminaires, the attention is drawn to energy consumption. Efficacy, therefore, the power consumption, is the most important selection criterion. But do you pay attention to the lifetime of the luminaire? What happens if the better efficacy luminaire has shorter lifetime? This means that you may have to renew the luminaires much quicker. This adds expenses and eats off the savings from the electricity bill.

Lifetime of LED Light Source

Compared to traditional light sources, the lifetime of an LED light source is long. When a traditional incandescent bulb or a fluorescent tube runs out of its lifetime, it can’t be used anymore. It either won’t produce light or starts to flicker. LED only loses some of its brightness and is, at least in theory, eternal.

This is the reason why the lifetime of LED light sources is measured in a different fashion compared to the traditional. The lifetime of a traditional light source means literally lifetime. LED’s lifetime tells that at what point the amount of light drops below the desired value.

The terms for LED Lifetime:

  • L70, L80, LXX = How much of the original lumens are still available. For example L70 means that the light source still produces 70% of the original lumens. So if the light source produced 1000lm at the beginning, this has dropped to 700lm.
  • B50, B60, BXX = How many light sources are below the given lumen value. So e.g. B50 means that 50% of the light sources don’t produce the desired amount of lumens anymore.

Typically the lifetime is given as a combination of these two. For example L70B50: 60.000h means that after 60.000 operational hours 50% of the light sources still produces at least 70% of original lumens.

aLED Moduulin elinikäennuste

Lifetime estimate of aLED module

The lifetime can also be given using only the L-value. For example L70: 60.000h. Then the manufacturer doesn’t actually promise how many of the luminaires are still over 70% after 60.000h.

Taking Lifetime into Account When Selecting Luminaires

Let’s assume that you are lighting a space that has 1000 luminaires. For example a shop. You have narrowed your luminaire choices down to two: Option A and Option B. Currently the space has fluorescent lighting and more specifically 58W T8 luminaires, which produce roughly 4000 lumens each. Here are your options:

  • Option A
    • Luminous Flux :4000 lumens
    • Efficacy 150 lm/W
    • Power: 26.7 W
    • Lifetime L70B50: 50 000 hours
    • Price 120€/Luminaire
  • Option B
    • Luminous Flux :4000 lumens
    • Efficacy 130 lm/W
    • Power: 30.8 W
    • Lifetime L70B50: 90 000 hours
    • Price 120€/luminaire

It’s easy to choose option A. The power consumption is lower as the power is around 4 watts smaller. For example in your 1000 luminaire space this means 4kW and a significant savings in your electricity bill.

When you know the daily operational hours, you can calculate the annual electricity consumption and compare that to the old solution. For the sake of an example, let’s assume that your shop is open for 14 hours a day. When you add the time for cleaning etc., your daily operational hours are 16. At least in this example.

This way you get the following math:

  • Annual operational hours: 16h*365= 5840 h/year
  • Price of electricity: 0.1€/kWh
  • Traditional (58W Fluorescent)
    • Annual electricity consumption: 1000*58W*5840h=338720000Wh= 338720kWh
    • Electricity bill: 338720*0.1=33 872.00€
  • Option A:
    • Annual electricity consumption: 1000*26.7W*5840h=155928000Wh=155928kWh
    • Electricity bill: 155928*0.1= 15 592.80€
  • Option B
    • Annual electricity consumption: 1000*30.8W*5840h=179872000Wh=179872kWh
    • Electricity bill: 179872*0.1=17 987.20€

 

Both LED options drop the electricity bill down to half of the old solution, saving you a lot of money. Option A saves a little bit more, thanks to the better efficacy and lower power consumption.

In short term, option A would be the better solution. As it saves more per year. Option A saves annually around 2.4k€ more than Option B.

However, it is very rare that investment this size is made with a one, two or even five years scope. That’s why we should do the math for a longer period.

When we take the lifetime into account, the situation changes a little.

Let’s first calculate the lifetime in your application. When the daily operational hours are 16, the annual operational time is 5840h, as calculated above.

With this, we can transform the lifetime into a more understandable form:

  • Option A:
    • 50 000h/5840h=8.6 years
  • Option B:
    • 90 000h/5840h=15.4 years

So you would have to change the option A after 8 years while the option B can still light your space for 7 more years (15 in total).

When we look at the total savings caused by the luminaires, the numbers look like this:

Savings in electricity bill after luminaire change

Savings in electricity bill after luminaire change

Lifetime (a) Option A Option B
1  17 582.29 €  14 447.26 €
3  52 746.88 €  43 341.78 €
5  87 911.47 €  72 236.31 €
10  55 822.93 €  144 472.62 €
15  143 734.40 €  216 708.92 €
20  111 645.87 €  168 945.23 €

As you can see from the calculations and the chart above, the option A is better in the short term. But when you look for a long term savings, the option B’s longer lifetime kicks in before the investment reaches 10 years. You will have to replace the option A almost twice as often as option B.

So when you look at the investment in a long-term, the lifetime becomes very important.

When choosing luminaires, you should focus your attencion to both: efficacy and lifetime.  The more expensive the luminaire and the investment is, the more important the lifetime is.