Dimmer switch

Switches with dimmer or dimmers (from English dim - dim, dim) are a device that is able to regulate the voltage on the consumer in the range from 0 to 100% of rated. Most often, dimmers are used instead of conventional switches to provide smooth adjustment of the brightness of the light.

Dimmer assignment

The main purpose of such devices is to control the brightness of the glow of incandescent or halogen bulbs. Halogen lamps that operate at reduced voltage are controlled by a dimmer connected via 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, special dimmers must be used.

To control energy-saving lamps, devices are used, the design of which includes an additional element - an electronic starter.

Using the brightness control as a light switch, you can arbitrarily change the light intensity from maximum to most dim. 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, the market offers several varieties of monoblock dimmers:

• 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 due to their quite reasonable price. There are dimmers with push or rotary way of inclusion. In the first case, to close the electric circuit, you need to lightly press the knob of the regulator, devices of the second type always turn on the light, starting with its minimum intensity.

• Dimmers with push button control. They are more complex devices, but their functions are greatly expanded due to the appearance of the possibility of combining such regulators into groups that can be controlled from the remote control Do.

• 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, the sensor models, like the previous type of dimmers, are equipped with signal receivers that allow you to change the light intensity using an infrared remote control or radio channel.

In addition to monoblock dimmers, there are devices with modular control, which is carried out using a remote button or key switch. Such regulators are used to control lighting in public places, as well as to install them in junction boxes.

As already mentioned, most models of dimmers are designed for use in circuits with incandescent or LED lamps.

When choosing a dimmer, special attention must be paid to its power, which should exceed the total maximum power of all consumers connected through this device. Today, in electrical goods stores you can find light controllers with a power of 40 W to 1 kW.

As for the design, the market offers single, double and triple dimmers. Moreover, the vast majority are single models.

Additional functions of dimmers

In addition to its main purpose - the smooth adjustment of light, some models of dimmers can be equipped with additional elements that allow you to perform a number of useful functions, to which relate:

1. Creating the effect of presence.
2. Various dimming modes, as well as flashing lights.
3. Auto on and off.
4. Voice and remote control.

Design of switches with dimmer

The main element of the design of the dimmer is the electrical circuit, which is designed to reduce the effective value of the voltage supplying the load.

Ensuring reliable operation of this circuit is carried out using several types of protection, which include protection against short circuit, high voltage and overheating.

Like a conventional light switch, the dimmer has a metal frame, which 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 bidirectional triode thyristor - a device that is an electronic switch controlled by a short impulse.

One of the most common schemes for dimmers is shown in the figure.

The signal for opening and closing the thyristor is carried out using a capacitor of a certain capacity that accumulates charge during the passage of the first half-wave of the supply voltage.

Principle of operation

Modern dimmers are not consumers of electric power. This is their fundamental difference from earlier analogues, which 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 was extremely costly. The use of a rheostat, in addition to significant financial costs, led to a significant increase in the mass of the light regulator. In addition, when current flows through the rheostat, it heats up very much, which leads to significant power losses and makes it necessary to take into account the need for cooling of this device.

Unlike a rheostat, an autotransformer is not a consumer of energy, 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, "cutting off" the front or back of the half-wave of the supply voltage. This principle of operation is called phase control with cutting off the leading or trailing edge.

The principle of operation of the dimmer, cutting off the leading edge of the half-wave of a sinusoid voltage:

The figure shows the form of the supply voltage in the circuit, the circuit of which contains a controlled thyristor, which is automatically switched 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.

Dimmer setting

Connecting a single dimmer is carried out in the same way as installing an ordinary keyboard 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 wiring diagram, as well as the dimensions of the socket and the marking of the terminals are absolutely identical.

Some difficulties may arise only if the dimmers are connected as pass-through switches or if they are combined into groups controlled by the remote control. The scheme of their connection of three outputs for connecting electrical wires.

Advantages and disadvantages of using dimmers

Benefits:

1. The possibility of arbitrary changes in the brightness of light in a room is not only significantly increases the usability of the fixtures, but also gives a wide scope for interesting design decisions.
2. Lowering the voltage at the consumer without power dissipation makes it possible to significantly save energy.
3. When operating at reduced voltage, the lamp life is greatly extended.
4. Using a dimmer is able to some extent protect the consumer from power surges, which are one of the main causes of failure of incandescent lamps.
5. The lamps are turned on at the moment the sinusoid of the supply voltage passes through zero, which prevents a sharp increase in the current in them.

Disadvantages:

1. The relatively high price of these dimmers compared to conventional key switches.
2. If it is necessary to replace a double or triple circuit breaker with a dimmer, significant difficulties arise associated with the acquisition of an expensive double dimmer model or equipment of additional points for installing two or three of these devices.
3. Distortion of the supply voltage curve. This disadvantage does not affect the result of the work of active energy consumers, such as incandescent lamps, too much. At the same time, the use of dimmers can extremely negatively affect the work of electronic consumers.

Thus, the use of dimmers as dimmers is quite justified in cases where a smooth change in the brightness of the light 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.