Electromechanical timer: the principle of operation and features of the time relay for turning on and off the light

Devices that turn on or off the light at a pre-set time are called time relays. They are very convenient and allow not only to save energy, but also to bring comfort to many areas of human life. You can find such an electric or electromechanical timer in many hardware stores and home appliance departments. Devices are of different types, differing in price and function.

Main characteristics

Monoblocs, which are timers, are most often built into a portable outlet, sometimes into an extension cord or adapter. This device controls the relay that connects the input and output contacts. It opens and closes them, thus stopping and restarting the supply of electricity to the connected device. The process is monitored and parameters are set through the control panel installed on the front of the monoblock.

Although different models of timers have the same principle of operation, they are quite different from each other. There are both simple mechanical devices and electrical ones with complex settings and many additional functions. They are designed to be used in different environments and for different purposes.

They differ in the following characteristics:

• the maximum time and size of intervals that can be set between turning on and off the outlet;
• accuracy and the highest error when triggered;
• the discreteness with which the switching time is set can vary from a few seconds to half an hour;
• the greatest current load that the timer can withstand - for ordinary household outlets, this figure is 16 amperes, but in industry higher values ​​may be needed;
• the number of switchings per day that can be set;
• the presence of additional features such as protection against splashes and exposure to high humidity.

Almost all devices of this type are equipped with a built-in battery that is charged from the mains, and can work even if there is no power for 100 hours or more. A full charge of such a battery takes 12-14 hours. In addition to switching relays in automatic mode, most models can also be simply turned on or off manually.

Device types

Different types of timers and time relays differ in their principle of operation, switching period, installation method and conditions necessary for their normal operation. All of them have their own advantages, disadvantages and features of work, which make each type of device suitable for its types of tasks.

Mechanical and electrical

Control over the mechanical timer is carried out through a wheel divided into sections, showing time intervals, and buttons or levers located on the front panel. Although a mechanical clock is built into it, which determines the time, the device's motor still requires power from the mains, therefore it would be more correct to call it electromechanical.

The smallest switching range on the device is 15 minutes. Such a timer is most often used to turn on and off the light with an interval of a day or a week, when the second-by-second accuracy and timing are not important. Its advantages include ease of setup and operation, as well as low in comparison with electrical models, the price, to the disadvantages - the inability to adjust the parameters to specific needs and the lack of a backup source nutrition. This model is well suited for simple tasks.

Among the most common breakdowns in electromechanical timers, wear of teeth and gears can be distinguished, due to which the adjusting wheel stops working. In order to cope with this, you will have to call a master, but the likelihood of such a malfunction is much less than a variety of damage to parts and wires of electrical devices.

The electronic timer for turning on and off the light is controlled by a microprocessor. It is configured by a person using the panel located on the front of the device. The parameters are displayed on a small LCD display and are saved in the device's memory when turned off. Such a timer works from a built-in battery or batteries that are charged from the mains through an outlet.

The advantages of an electric timer in comparison with a mechanical one include a large selection of settings, the ability to set precise trigger parameters and visually see them on the display, minimal errors in time calculation and the ability to create small, up to a minute, ranges switching.

Among the disadvantages, it is worth noting the higher price, as well as the fragility of such devices - sometimes their battery, parts and software fail. In addition, they are more susceptible to negative environmental influences and require additional protection from it.

By time of switching on and off

In addition to the principle of operation, timers differ in operating periods and response ranges. On this basis, they can be divided into the following groups:

• Daily allowance - switch relays at the same time every day. Most often they are used in cases where it is necessary to turn on the lighting in the evening and turn it off during the day - for example, for automatic regulation of street lights, illuminated signs, neon signs, aquarium lights or fountain. Due to the change in daylight hours during the year, this type of timer often needs to be readjusted.
• Weekly - switch relays at different times with fine tuning of the program for each day of the week. Suitable, for example, if you need to turn off all electrical equipment at the workplace on weekends or keep activated security alarm in the garage only on those days and hours when the owner is not using machine. This type of adjustment is most often used in electrical models of timers, which are able to keep information about settings in their memory for 7 days and repeat the cycle constantly. If the program is the same every day, then it is better to give preference to a cheaper daily timer.
• Astronomical - they are similar to daily, but have a built-in annual program for determining daylight hours and adjust the parameters in accordance with it automatically. More convenient due to the absence of the need to change the settings manually, but also more expensive, since the device memory must contain a program of changes for a whole year.
• Random - turn on and turn on the light not at the same time, but always at different times. It is selected by a random number generator built into the device. They are used most often in order to create the effect of the presence of residents in a house or apartment and thereby protect it from thieves.
• Countdown timers - turn off lighting or other electrical equipment some time after turning it on manually. They are used to save energy when turning on the light in entrances, corridors and other rooms that a person does not use constantly.

There are also universal multifunctional devices with the ability to set parameters for any of these operating modes and combine them. But they are more difficult to operate and set up, so you shouldn't buy them unnecessarily.

Socket and stationary

By the type of installation, light timers are divided into socket and stationary. The first of them are connected to the electrical network through a socket using a standard plug, the second are placed in a specially installed box or rail of the separator board.

The socket relay is convenient when you need to control the operation of a separate electrical appliance or lighting in the same room. They are easy to install and use, are small in size, do not require auxiliary wiring for installation in the power grid, and can be moved from place to place as needed. A stationary relay does not share these advantages, but compensates for them with the ability to control the operation of electrical equipment in the entire residential building or work building at once. If this is exactly what is needed, then its installation will be much more convenient and profitable than using many mobile devices, even with all the disadvantages of this type of device.

By working conditions

When choosing a timer, it is sometimes important to have conditions under which they can work normally. For example, a device installed to adjust an automatic watering system for plants should continue to function when exposed to splashes of moisture, and the timer installed in the workshop will need protection against dust.

The protection class of time relays, like other electrical appliances, is determined by the IP system. In total, there are 7 levels of protection against dust and 10 - against water, as well as additional designations of the device's resistance to weather, high voltage and other factors. They are indicated in the technical specifications of the device. The timer should be selected in accordance with the conditions of the room in which it will then be installed.

In addition to protecting against harmful influences, it is necessary to take into account the maximum power of the devices that can be connected to the timer. In total, it should not exceed this indicator for the device itself. You can find it out in the instructions or on the information plate on the time relay case.

Timer functions

Electric and electromechanical timers are used to automatically control not only lighting, but and other electrical appliances: heaters (including underfloor heating systems), air conditioners, hoods and others. Compared to permanent manual switching of devices, the use of a time relay has the following advantages:

• energy savings;
• constant maintenance of the required temperature and lighting level in the room - for example, the timer can turn on the heater or an air conditioner some time before a person comes home and already create comfortable conditions in the room in front of him appearance;
• the ability to control yard and garden lighting, as well as other equipment located outside (for example, plant watering systems) without going outside;
• switching electrical appliances on and off according to a strict schedule even when there are no people nearby - especially important for aquariums and terrariums, in which the correct operation of filters, light-heat lamps, heaters and other equipment is vital for inhabitants;
• timely shutdown of household appliances after the person who turned on the equipment has already left - widely is used in the construction of stoves and washing machines, since even the simplest mechanical timers.

Thus, time relays are quite common and are found everywhere in a person's daily life. They are inexpensive, but they significantly increase comfort and save time and effort, which has brought them popularity.

Criterias of choice

There is nothing complicated or unusual in choosing and buying a time relay. First you need to determine why such a device will be needed, what it will be used for and in what conditions it will work. Then you need to look at the following characteristics:

• discreteness of setting the switching time;
• instrument accuracy;
• the number of different set programs;
• the degree of protection from the effects of the external environment;
• maximum power of connected devices;
• convenience, clarity and accuracy of settings;
• the ability to connect several plugs to the relay at the same time;
• affordability of the price.

Comparing these characteristics with the purpose for which the time relay is purchased, it will not be difficult to choose the right model. In this process, you should not chase the most expensive and sophisticated devices - if necessary, for example, just all the time turn on and off the light at the same time, then a simple and cheap electromechanical timer with a clock will be quite enough. You can buy a timer in any electronics department or a specialized online store.