Timer relay (RT) is an electrical device designed to create a time delay. Depending on the selected group of contacts (normally closed or normally open), it can turn on or off certain consumers for a certain time.
There are several types of time relays with different time ranges, purpose, device and principle of operation. In the article we will talk about all their types and help you decide which type of time relay to choose for specific tasks.
Intermediate relays
Intermediate timers of time relays are needed to create a time delay in mechanisms. For example, when starting the engine, it consumes 7-10 times the nominal current, which leads to the operation of the current relay. Removing the current relay is not an option, because in the event of a problem with the engine, it can fail.
To solve this problem, the current relay is shunted using a time relay so that at the time of start-up the starter does not lose power due to the current relay and goes to normal operation, after which the relaytime stops shunting the current relay, and if there is a problem with the motor, it will still be protected. For this purpose, a relay with an anchor or clock mechanism is used. The principle of operation is the same as that of the watch. The electromagnet starts the clock mechanism, and after the time has elapsed, the relay performs its function (depending on the group of contacts). The operating limits of such relays are from 0, 1 to 20 seconds.
Pneumatic relays
Pneumatic relays are not suitable for the previously described situation, but will quite cope with tasks that require cycling. The principle of operation is such that there is a chamber in which there is a hole and a piston with an anchor. When a signal is received, the electromagnet pulls the anchor, and depending on the set time, the diameter of the hole changes, respectively, and the rate of filling / emptying the chamber with air. This sets the time delay. Delay limits up to 60 sec.
Electromagnetic relays
Electromagnetic time relays (timer) are applicable in DC circuits, but are practically not used in everyday life. The only example for domestic use is the creation of a flasher, which is based on this very relay. The mechanism is such that there is one short-circuited turn on the electromagnetic coil, which, due to the residual magnetic field, keeps the mechanism from going into a normal state. The delay limits are only 5 seconds.
Electronic relays
Electronictime relay timers have wide regulation limits, and their work is based on natural processes, such as the charge-discharge of a capacitor, which starts counting in seconds.
These same processes bring the whole mechanism into action. They can have a lot of applications, due to the wide range of regulation of the time interval. But the price of such devices bites, and they are suitable for a single time setting. In fact, electronic relays are obsolete, and they have been replaced by microprocessor relays with a programmable time delay setting, on / off periods, that is, in fact, you can set a schedule for when, what time, how much to turn on the consumer. These time relays are called cyclic.
Cyclic relays
Cyclic time relays (programmable timer) turn on or turn off the consumer at a certain time and for a certain period of time. The work is based on microprocessor technology and electronics. They find their application both in everyday life and in production. In everyday life, this is rather not a time relay, but a cyclic timer that turns on and off, for example, the backlight of an aquarium, terrarium, street lighting. By setting the program, you can set that the aquarium lighting should turn on at 19:00 and turn off at 06:00. The use of the device in everyday life is very different. And its price, first of all, depends on the accuracy, as well as the power that it can turn on and off.
With the most basic knowledge of electrical engineering, you can expand the limits of workhousehold timer time relay by power. By purchasing a magnetic starter and including the coil contacts through a time relay, and power contacts to the network, our starter will turn on at the time intervals that we set on the household timer. And the power is now limited not by the timer, but by the starter.
By purchasing the cheapest timer and starter, for example, PME 111, we will increase the maximum current to 10 A, including timers and time relays in the socket, which is not bad. Such schemes are useful when there is, for example, a large container that takes a long time to fill. Having assembled such a circuit, you can once detect the time of filling the container and turn on the pump through this simple circuit. And so with any consumer.
