Dimmable switches or dimmers (from English dim - dim, dim) are a device that can regulate the voltage at the consumer in the range from 0 to 100% of the nominal. Most often, dimmers are used instead of conventional switches to smoothly adjust the brightness of the light.
Purpose of the dimmer
The main purpose of such devices is to regulate the brightness of incandescent or halogen light bulbs. The control of halogen lamps, which operate at low voltage, is carried out using a dimmer connected through a step-down transformer. These devices can be purchased separately, but it is better to buy a dimmer with a built-in transformer.
Attention! To work in lighting circuits with LED and fluorescent lamps, it is necessary to use special dimmers.
To control energy-saving lamps, devices are used, the design of which includes an additional element - an electronic starter.
Using the dimmer as a light switch, you can arbitrarily change the intensity of lighting from maximum to the most subdued. In this case, there is no need to use double or triple switches to control the operation of chandeliers with several lamps. In addition, it makes no sense to purchase expensive fixtures equipped with their own voltage regulators.
Classification of dimmers
Currently, there are several varieties of monoblock dimmers on the market:
- Dimmers with a mechanical regulator, which is made in the form of a rotary disk. The design of such products is relatively simple, which is the reason for their quite reasonable price. There are dimmers with push or turn on. In the first case, to close the electrical circuit, it is necessary to lightly press the regulator knob, devices of the second type always turn on the light, starting from its minimum intensity.
- Push button dimmers. They are more complex devices, but their functions are greatly expanded due to the possibility of combining such controllers into groups that can be controlled from the remote control.
- Touch dimmers. They are quite expensive, but also the most prestigious devices that fit perfectly into the interiors of rooms decorated in a modern style. In addition, touch models, like the dimmers of the previous type, are equipped with signal receivers that allow you to change the intensity of lighting using an infrared remote control or via radio.
In addition to monoblock dimmers, there are devices with modular control, which is carried out using a remote button or rocker switch. Such regulators are used to control lighting in public places, as well as to install them in junction boxes.
As already mentioned, most dimmer models are designed for use in circuits with incandescent or LED lamps.
When choosing a dimmer, it is necessary to pay special attention to its power, which must exceed the total maximum power of all consumers connected through this device. Today, in electrical stores, you can find dimmers with power from 40 W to 1 kW.
As for the design, there are single, double and triple dimmers on the market. At the same time, the vast majority are single models.
Additional functions of dimmers
In addition to its main purpose - smooth adjustment of light, some dimmer models can be equipped with additional elements that allow you to perform a number of useful functions, which include:
- Creating the effect of presence.
- Various dimming modes, as well as flashing lights.
- Automatic switching on and off.
- Voice and remote control.
The design of switches with a dimmer
The main element of the dimmer design is an electrical circuit, which is designed to reduce the effective value of the voltage supplying the load.
Ensuring the reliable operation of this circuit is carried out using several types of protection, which include protection against short circuit, overvoltage and overheating.
Like a conventional light switch, the dimmer has a metal frame that allows you to easily install it in a standard socket.
Device diagram
The main element of the electrical circuit on which the dimmer switch is built is a bidirectional triode thyristor - a device that is an electronic switch controlled by a short pulse.
One of the most common dimmer circuits is shown in the figure.
The signal to open and close the thyristor is carried out using a capacitor of a certain capacity, which accumulates a charge during the passage of the first half-wave of the supply voltage.
Principle of operation
Modern dimmers are not consumers of electrical power. This is their fundamental difference from earlier analogues that worked according to the scheme of an active or capacitive voltage divider.
Previous generations of voltage regulators were either rheostats connected in series with the load or autotransformers. In both cases, the manufacture and use of such devices proved to be extremely costly. The use of a rheostat, in addition to significant financial costs, led to a significant increase in the mass of the dimmer. In addition, when current flows through the rheostat, it becomes very hot, which leads to significant power losses and makes it necessary to take into account the need to cool this device.
Unlike a rheostat, an autotransformer is not an energy consumer, but it has an extremely large mass and dimensions.
It is possible to avoid power losses in the dimmer due to the electrical circuit, which allows you to supply power to consumers by “cutting off” the front or rear half-wave of the supply voltage. This principle of operation is called phase control with cutting of the leading or trailing edge.
The principle of operation of a dimmer that cuts off the leading edge of a half-wave of a voltage sine wave:
The figure shows the form of the supply voltage in the circuit, the circuit of which contains a controlled thyristor, which is automatically turned on when the voltage reaches zero.
Depending on the operating mode, which is determined by the response time (from 0 to 9 ms), it is possible to achieve a smooth change in the power consumed by the lighting device.
Installing a dimmer
The connection of a single dimmer is carried out in the same way as the installation of an ordinary rocker switch. Thus, when installing a dimmer instead of an existing switch, there is no need to make any changes to the design of the electrical wiring.
The connection diagram, as well as the dimensions of the socket box and the marking of the terminals are absolutely identical.
Some difficulties may arise only in the case of connecting dimmers as pass-through switches or combining them into groups controlled from the remote control. The scheme of their connection of three outputs for connecting electrical wires.
Advantages and disadvantages of using dimmers
Advantages:
- The ability to arbitrarily change the brightness of the light in the room not only greatly increases the ease of use of the lamps, but also gives wide scope for interesting design solutions.
- Reducing the voltage at the consumer without power dissipation makes it possible to significantly save energy.
- When operating at low voltage, the life of the lamps is significantly extended.
- The use of a dimmer can to some extent protect the consumer from voltage surges, which are one of the main reasons for the failure of incandescent lamps.
- The lamps are turned on at the moment when the sinusoid of the supply voltage passes through zero, which prevents a sharp increase in current in them.
Flaws:
- The relatively high price of these dimmers compared to conventional rocker switches.
- If it is necessary to replace a double or triple switch with a dimmer, there are significant difficulties associated with the acquisition of an expensive double dimmer model or equipment for additional points to install two or three such devices.
- Distortion of the supply voltage curve. This disadvantage does not greatly affect the result of the work of active energy consumers, which are incandescent lamps. At the same time, the use of dimmers can have an extremely negative impact on the operation of electronic consumers.
Thus, the use of dimmers as dimmers is quite justified in cases where a smooth change in light brightness is really necessary. At the same time, due to the high cost of these devices, using them instead of all the switches in the apartment seems inappropriate.
