In the power supply circuit, the relay is also called a contactor. The time relay is an electrical element that is used to turn on or off a circuit of higher voltage and higher current, which is used in a circuit of lower voltage or smaller current. It is generally divided into two types of power-on delay and power-off delay.
A time relay is a control device that uses electromagnetic principles or mechanical principles to implement time-delay control. Many of its kind, air damping type, electric and electronic type.
Air-damped time relays are often used in AC circuits. They use the principle of air throttling orifices to obtain a time-delayed action. It consists of three parts: electromagnetic system, time delay mechanism and contacts. The time delay range of the air-damped time relay is large (0.4~60s and 0.4~180s), and its structure is simple, but its accuracy is low.
When the coil is energized (voltage specification has ac380v, ac220v or dc220v, dc24v, etc.), the armature and the pallet are attracted by the iron core and momentarily move down, making the momentary action contact open or closed. However, the piston rod and the lever cannot fall along with the armature at the same time, because the upper end of the piston rod is connected with the rubber membrane in the air chamber. When the piston rod begins to move downwards under the action of the release spring, the rubber membrane is depressed downwards. The air in the air chamber becomes thin and the piston rod is damped and slowly descends. After a certain period of time, the piston rod is lowered to a certain position, and the delayed contact action is pushed by the lever so that the movable contact point is opened and the movable contact point is closed. The energization from the coil to the delayed contact completes the operation. This is the delay time of the relay. The length of the delay time can be changed by adjusting the size of the air intake hole in the air chamber.
After the draw coil is de-energized, the relay recovers by restoring the spring. Air is rapidly expelled through the vent.