Since the invention of electric lighting, the question of dimming has arisen. At first, mechanical devices were used for this, blocking part of the beam (curtains, etc.). It was cumbersome and inconvenient. Then potentiometers and adjustable transformers began to be used for this. It was unreliable and not economical. With the development of solid-state power electronics, it became possible to create compact devices for changing the brightness without undue energy consumption.
Content
Dimmer as a device for regulating the intensity of the glow
The name of such devices comes from the English to dim - darken. When the device is in operation, you can set the required level of lighting or create color effects, including dynamic ones, as well as achieve certain energy savings.
From the user's point of view, changing the intensity of the glow occurs by manipulating the instrument's controls - the rotary handle, the "more-less" buttons, the remote control, etc.
From the point of view of a developer of a lighting system (even a small home one), it is necessary to better understand the processes leading to a change in the brightness of a lighting device.
The principle of dimming
For lamps operating in alternating current circuits, dimming is done by reducing the current by “cutting out” part of the sinusoid.
The more voltage is cut, the less current through the lamp. The brightness is averaged due to the inertia of the lamp filament and human vision.
Classic dimmers are performed according to the above scheme (small variations are possible). The key is triac - it opens and closes at a given time after the voltage passes through zero. The later the triac opened, the smaller part of the sinusoid goes to the consumer. This moment is regulated by a potentiometer.
What lamps can work with a dimmer
The classic dimmer controls the average current through the fixture, so it's ideal for changing the level of light. incandescent lamps and halogen lamps. Fluorescent lamps are arranged differently, so they do not work together with dimmers, with the exception of special lighting fixtures that have a special design and are marked "Dimmable".
Adjusting the brightness of LED lamps has its own characteristics. Many LED lamps are equipped with a current stabilizer (driver).It keeps the current through the LEDs stable despite changes in input voltage. That is, it performs functions opposite to a dimmer. Therefore, brightness adjustment is not possible in this case. The exception is lamps, the input circuits of the drivers of which are supplemented with a special circuit. Such lamps are labeled Dimmable.
Another option is that the current in the lamp is limited by a resistor (this solution is used in LED strips, etc.). There is also a problem here - it is extremely undesirable to turn on LEDs in an alternating current circuit.
The weak point of LED is low resistance to reverse voltage. When you turn on such a lamp in a household network, it will quickly fail, despite the fact that it is designed for a voltage of 220 volts. It is necessary to turn on such lamps in a DC circuit, and the brightness is regulated by the method PWMwhere a positive polarity voltage is applied.
The luminous flux of LED is averaged due to the inertia of human vision. For LED strips (and other similar lighting devices) you need a special dimmer that works on the PWM principle.
Important! All LED strips are dimmable. The Dimmable label, implying the existence of non-dimmable tapes, is a marketing ploy.
Types of dimmers and their connection diagram
Dimmers with mechanical manual control are made according to the classical scheme and are switched on like light switches in a phase wire break (usually dimmers have a built-in switch). They even come in a consumer lighting switch form factor for ease of installation and installation.
The simplest dimmers turn off the lighting when the handle is turned from the minimum lighting position to the extreme position (until it clicks).The disadvantage of such a system is that after switching on, each time it is necessary to re-set the desired lighting level. More advanced devices adjust the light level by turning the handle, and turn the light off and on by pressing it. In this case, the brightness level does not change.
Dimmers with a higher level of comfort (touch, with remote control, with regulation by means of an audio signal, etc.) are connected both to the break in the phase wire and to the neutral conductor. This is due to the need to power the internal control circuit. If the dimmer is controlled from a computer (mainly to create lighting effects on LED strips), then a separate power supply from the mains is provided for it.
Separately, it is necessary to consider the connection diagram of the pass-through dimmer. This is a dimmer that can work in a system with a pass-through switch. Such switching devices are located, for example, at two ends of a long corridor. Lighting can be turned on when entering a corridor and off when exiting, regardless of the position of the other switch.
If this system is supplemented with a dimmer, then the level of illumination can be changed. The dimmer is installed only on one side - if you install it on two, then the result of double cutting one sinusoid will be unpredictable.
If you equip the dimmer with its own group of changeover contacts, you get a pass-through dimmer. It allows you to turn off and turn off the lighting regardless of the position of the other device and adjust the brightness.
Portable dimmers should also be mentioned. They are used for floor lamps, table lamps, etc.Such a dimmer switch is plugged into a socket, and already in its connector you can connect a lamp and adjust its glow level.
Modular dimmers have been developed and used to illuminate premises without permanent human presence (entrances, warehouses, etc.).
They have a regulator block and an on-off switch spaced apart in space. The main module is located, as a rule, in the electrical switchboard and is included in the general power supply system. The remote switch is mounted in any accessible place - at the entrance to the room, on the control panel, etc.
The adjustment body for setting the illumination level is located on the body of the main unit. The required brightness of the lamps is set during setup. Such a regulator can be switched on manually or automatically - in this case it is supplemented by a motion sensor, capacitive relay, etc.
Such dimmers (except for Economy class models) have additional functions, such as a smooth rise and fall of the light level, etc.
There are modular regulators for creating Master-Slave systems. The level and algorithm of operation are set on the master device, the rest repeat the settings that are transmitted over the communication lines.
Typical connection errors
If the dimmer is connected to a lamp, and the brightness cannot be adjusted or the lamp does not light up at all, first of all, you need to check compatibility (or it is better to check it before starting installation upon purchase). If the luminaire can be non-dimmable or dimmable, look for the Dimmable marking on it. When choosing a dimmer, you need to determine what load it is intended for - this is also can identify by label.
| Letter marking | Symbol | Type of load | Compatible Lamps |
|---|---|---|---|
| R | Active (ohmic) | incandescent | |
| C |  | Reactive capacitive character | With electronic control gear (electronic transformer) |
| L |  | Reactive inductive nature | Low voltage halogen lamps with conventional transformer |
In addition, the lighting system may not work due to common installation errors - turning on the device instead of breaking the phase wire into a neutral break, etc. To avoid this, you need the usual care during installation.
Also, selection errors can be associated with load power - each dimmer has its own limit. It is necessary to buy devices with a margin of 15 ... 20% in terms of lamp power. Subject to this simple rule, the dimmer will work for a long time and reliably.
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