The idea of controlling the intensity of the light in the room appeared simultaneously with the lighting itself and this problem was solved in part in different ways. While candles were being used – it was controlled by the size and number of candles, the kerosene lamps – by changing the length of the wick. When incandescent bulbs took the place of candles, it turned out that the problem of controlling the intensity of light remained. Of course, there were lamps of different capacities and a certain number of lamps could be used to choose the optimal intensity of light in the room or on the street, but it was not possible to change the light intensity of the source itself because the voltage is constant, and to install for each light source a transformer with variable transform coefficient was a senseless idea.
The situation has improved with the change of thyristor diode. Thyristor is a semiconductor device that can only pass the sinewy side of the alternating current. In addition, by changing the voltage on the thyristor control electrode, you can control the degree of current transmission. Thyristors have been used to control brightness, but extremely rare. In everyday life, they met even less.
When LEDs with their own power supply – a driver – were used in the manufacturing industry, many manufacturers thought the introduction of light control in the lamp driver – it was a good idea. That’s how the dimly powered drivers came up.
But if the driver in turn could change the current power and the lamp voltage, only the problem of controlling the driver itself, how to communicate the voltage to the lamp, remained.
Initially, the “thyristor” method was used. Two conclusions were made on the driver. By changing the voltage between 0 to 10V, it was possible to control the driver’s power. It’s simple: 0V – the light is off, 5V – the lamp works at 50% brightness, 10V – the lamp works at full power. Some manufacturers used a range not from 0-10V but from 1-10V, but the principle remained the same. This control protocol was named “0-10V”.
Until now, the “0-10V” protocol all fit. But with the development of the lighting industry, lighting requirements for housing have changed. A large number of lighting devices began to appear in homes, and more flexible lighting settings were required, and were difficult to solve using the “0-10V” protocol. The problem with the “0-10V” protocol is that we can not adjust the level of illumination of each individual luminaire. More precisely – we can, but in this case, for each lamp it is needed the controller and its own harness. Considering that in a modern house there may be more luminaires and each has to implement different lighting scenarios, the wiring turns into a nightmare. It is necessary to look for another lighting control system.
For this, European manufacturers have developed a new protocol – DALI (Digital Addressable Lighting Interface). Controllers and actuators – the lighting drivers are connected through a common two-wire bus. When the lighting control system is initialized, all lamps receive their personal address from the controllers and execute commands only if they are sent to that address. There results a local miniature network. Only one device can be connected to 64 devices. If this number is not enough, it is possible to connect a DALI controller (router) instead of one of the execution units and obtain another 64 addresses and so on up to the theoretical limit of 12,800 devices. The operating voltage on the DALI controller bus is 16V, which makes it possible to install this bus near the power wires and even use two free wires from a power supply cord, because with this operating voltage, the take-up from the power wires does not affects the performance of the DALI bus.
Despite all the benefits of the DALI lighting control system protocol, the 0-10V protocol is also very used. Each of them has its own scope.
For example, if it is necessary to control an object with a large number of devices, provided that different lighting scenarios are possible, the DALI protocol and DALI lighting system is more than needed. Well, if one or two luminaires are connected to a controller whose mode of operation should not differ, then the “0-10V” protocol will be installed due to the simplicity of deployment, configuration and cost of the equipment.
Speaking of the usual cases of using these two protocols, we can give the Smart House Project, which is simply impossible to do without DALI lighting control system devices. The “0-10V” protocol is used, for example, to control street lights, where a lamp is usually accompanied by a controller.
Therefore, when designing lighting control systems, it is necessary to evaluate the advantages and disadvantages of using each of the protocols and choose the most suitable for features, comfort and price.