Often, in electrical circuits for connecting electrical power equipment, it is necessary to turn it on not at the time the switching apparatus starts to work, but after a certain time interval. This is mainly used on machines where people work directly, or on high-voltage powerful equipment for step-by-step starting in order to avoid damage from starting currents. For such cases, a special apparatus is made on which it is possible to set any necessary period of time.
On delay relays - what is it
A special temporary relay is used for switching electrical circuits of various capacities and is used in automatic control circuits. There are several types of on-delay relays:
- Block time relays differ in external design and their own power supply, an example of the use of this type is the time delay during photo printing.
- Built-in timers do not have their own power supply, they are performed in the form of prefixes to the main switching equipment. An example of using such a relay is a timer in a washing machine.
- Modular relays have some similarities with block relays and are mainly used for electrical circuits and are installed on the DIN rail in the shields.
Also, according to the principle of operation, they are divided into electromagnetic, pneumatic, motor, with a clock or anchor response mechanism, electronic.
Principle of operation
The time delay relay, like a conventional switching relay, consists of an electromagnetic coil, a core mechanically connected to the contact group. The only difference is the special mechanism that prevents the coil from tripping at the moment of inclusion of electric current in the circuit. At the same time, the mechanism withstands a certain period of time, which is set by trained personnel when setting up a delay timer for switching on with your own hands or remotely using electronic control panels from the control room.
The main advantage of a time relay is its cost-effectiveness, since due to time intervals it is possible to achieve a shutdown and inclusion of equipment only when necessary. Another important advantage is the long term of independent, autonomous work. Also, the advantages include the ease of control and commissioning both with direct contact and with the remote setting of the parameters of temporary exposure.
Specifications
We highlight some characteristics that you should pay attention to when choosing a specific delay relay:
- The supply voltage of the electrical element, in this case, is a coil.
- The maximum allowable current that the device can pass without damaging the contacts and important components.
- The required time range in which the relay will be adjusted.
- The estimated voltage of the device.
- Operating temperature range. Usually it is from -20 ° C to +55 ° C.
- The highest value of the cross section used for switching the cable.
- Degree of protection - not lower than IP 24.
- Adjustment method (there are digital and analog).
- Ability to connect additional devices.
- The method of installation in the shield or on the street yourself.
Appointment
The main purpose of the on-delay relay is to provide the necessary time interval for a certain connection of various elements of the electrical circuit. It is often used for automatic control in circuits and for connecting remotely defined power equipment. It is also possible to turn on the equipment in a certain period of time, which is very convenient for remote control.