Based control systems lighting is often used pulse relay. How is it organized? This is a common relay that has a built-in pulse counter. Therefore, it has pins to connect to the driven circuits and a place for unit installation for pulse counting. There are two types of impulse relays: Electromechanical and electronic. Consider the example of one such relay.
Any pulse received by the control unit with a built-in relay affect the switching power of the contacts inside of it. If the contact is closed, it opens, if on the contrary open — closed. If the network is suddenly lost tension, then nothing will change, the contacts will remain in the same position as they are fixed mechanically. Such a mechanism is the much better device of a conventional starter that whenever lost the voltage needed to activate a new.
What is the usability of such a relay? In fact, this simple mechanism allows you to control the system from more than two places. This is achieved by interacting a pulse on the contacts inside the system from any point. It is close to the system like a Smart home. Inside the box is necessary to set the pulse relay for a particular group of contacts and set for her switch. Thus, we have the opportunity to enable/disable an entire group of contacts. Below are two diagrams of typical use, in practice such a mechanism.