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 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.
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.
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.
Figure 3. The example of terminal block to connect the LED driver into the electrical network.
Finally, as for physically connecting a COB LED into the LED driver, you have two ways to do it:
solder the wires on the solder pads of the COB
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.
You can use several different dimming options to dim LED Lighting. What are the possibilities and what dimming should you look from a LED driver? I’m going to answer these questions in this blog post by going through the different systems.
The goal is to give you the basic understanding of the dimming methods available at moment.
I am grouping the dimming methods in two main groups: analogue and digital.
When you want to control lighting, you have to know some basic issues of your lighting fixtures:
Are your fixtures dimmable? If yes, what is the dimming method which works together with your fixtures
If your fixtures are non-dimmable, then you can only have on/off – function.
Analogue dimming covers all dimming systems that don’t transform the dimming signal into bits and controls the lighting in analogue manner.
Phase dimming systems dim the lights by altering the supply voltage.
Leading & trailing edge dimming
Before LEDs, we used to dim halogen lamps with wall dimmers. We can still use these kinds of dimmers. But dimmer, driver and LED-module must be compatible with each other.
This type of control is accomplished without any need for an additional control wire. It involves connecting a dimmer in series between one of the mains wire and the equipment.
The dimmer cuts part of the mains voltage sinusoidal waveform to a greater or lesser extent in order to dim luminous flux even from 1% to 100% (this value depends on dimmer and driver).
Depending on how the driver makes the mains voltage cut, it is possible to distinguish between two types of dimming:
Trailing edge dimming
Dimming cut-off in the wave on its ascending side, from the beginning (phase cut-off at ignition). This is traditionally used in halogen lamps supplied through electromagnetic transformers.
Dimming by cut-off in the wave on its descending side, from the end cutting backwards (phase cut-off at switch off). And this way of dimming causes less interferences than leading-edge dimming.
There are dimmers and equipment that support both types of dimming, and others that support only one type.
Leading & Trailing-edge dimming LC
Leading-edge dimming L
Trailing-edge dimming C
The 1-10V system enables dimming of the luminous flux from around 1…10% to 100%. This is done by sending an analogue signal to the equipment over an additional, two-wire control line. These control wires have positive and negative polarities respectively and that must be kept in mind when wiring up the system.
The analogue signal has a direct voltage value of 1V to 10V. 1V or short-circuiting the fixture’s input control gives the minimum light level. While 10V or leaving the input control circuit open gives out the maximum light level.
International standard, IEC 60929, defines the regulation curve. The regulation curve represents the relationship between the control line voltage and the luminous flux. It reflects a practically linear relationship in the range of 3V to 10V.
To get a response adapted to that of the human eye it is possible to use logarithmically controlled potentiometers.
Regulation curve by IEC 60929
These in light fixtures generate power control with 1-10V dimming. Driver supplies a current to the controller through equipment control terminals. The controller current must be from 10µA to 2mA. The maximum control line current is obtained with a voltage of 1V and the minimum with a voltage of 10V.
This dimming system is unidirectional, i.e. the information flows in one direction, from the controller to the light fixture. The latter generates no feedback to control. This means that this system can’t be controlled by a software. Groups have to be created by wiring. This system can be integrated into building control systems.
The voltage drop in the control line wiring limits its length. Therefore, the maximum distance is limited by the number of control gears connected. The latter establishes the current per line and the cable diameter used.
Touch Control Push Button (analogue but can be connected to digital systems)
Touch Control is a system that enables the simple and economic dimming of luminous flux. It uses the mains voltage as a control signal, applying it with a standard push button on a control line, without any need for specific controllers. The Touch Control system enables you to carry out the basic functions of a regulation system with a power-free pushbutton. Depending on how long the button is pressed it is possible to switch the light on or off or dim it. Switching the light on or off is done by short, sharp pressing or “click”. If the button is pressed for a long time it is possible to dim the luminous flux between the maximum and minimum levels alternately.
This is a unidirectional interface, i.e. information flows in one direction. The equipment does not generate any type of feedback, so it can’t be controlled with a software. Groups have to be created by wiring. This system cannot be integrated into building control systems.
The length of the wiring and the number of equipment that can be connected, are theoretically unlimited. But in, asynchronism may occur during switching on and dimming, at distances longer than 25 meters, and with a larger number of fixtures connected. Owing to its characteristics, the use of this dimming method is recommended for individual offices, small meeting rooms or bedrooms, landings and small spaces in general.
Digital dimming covers all dimming systems that transform the dimming signal into bits and controls the lighting in digital format.
DALI Regulation (digital)
As revealed by the meaning of its acronym, Digital Addressable Lighting Interface, DALI is a digital and addressable communication interface for lighting systems.
This is an international standard system in accordance with IEC 62386, which ensures compatibility and interchangeability between different manufacturers’ equipment marked with the following logo: DALI controller
It is a bi-directional dimming interface with a master-slave structure. The information flows from a controller, which operates as the master, to the control gears that only operate as slaves. The latter carries out the orders or responds to the information requests received.
Digital signals are transmitted over a bus or two-wire control wire. These control wires can be negatively and positively polarized, though the majority control gears are designed polarity free to make connection indifferent.
You don’t need especially shielded cables. It is possible to wire the power line and DALI bus together with a standard five-wire cable.
Unlike other systems, you don’t need to create wiring groups. Therefore all the pieces of fixtures are connected in parallel to the bus. Without bearing in mind the grouping of these, simply avoiding a closed ring or loop topology.
You don’t require mechanical relays to switch the lighting on or off, given that this is done orders sent along the control line. You don’t need are bus termination resistors either.
Consequently, the DALI interfaces offer wiring simplicity in addition to great flexibility when it comes to designing the lighting installation.
The maximum voltage drop along the control line must not exceed 2V with the maximum bus current of 250mA. Therefore, the maximum wiring distance allowed depends on the cable cross-section, but it must never exceed 300m in any case.
After wiring, the DALI lighting system is configured with the software. You can create up to 16 different scenarios, addressing the equipment individually up to a maximum of 64 addresses. This can be made with groups up to a maximum of 16, or simultaneously by means of a “broadcast” order. You can change the configuration at any time without any need for re-wiring.
The DALI system has a logarithmic regulation curve adjusted to human eye sensitivity, defined in the international standard, IEC 62386. The possible regulation range is set at from 0.1% to 100%. The driver manufacturer determines the minimum.
DALI Regulation Curve by IEC 62386
With the software, you can change the “fade rate”. “Fade rate”is the time needed to go from one light level to another(fade time) and the speed of the change.
The DALI system lies in the fringe between the complex and costly but powerful ones; control systems for buildings that offer total functionality and the most simple and economic regulation systems, for example, the 1-10V one.
You can use this interface in simple applications independently, to control a luminaire or a small room. You can also use it in high-level applications such as being integrated by gateways into building smart control systems.
These are the most common systems you can use to dim LED. There are a lot of different dimming systems for different driver manufacturers. I can’t cover all of those in a single blog post. I will be writing a different post about wireless dimming options.
If you have anything you would like to know, you can always contact me firstname.lastname@example.org .