Electrical symbol and contact form of relay
The relay coil is represented in the circuit by a long box symbol, and if the relay has two coils, two long boxes are drawn side by side. At the same time, mark the relay word symbol "J" in or beside the long box. There are two ways to represent the contacts of relays: one is to draw them directly on one side of the long box, which is more intuitive. The other is to draw each contact into its own control circuit according to the needs of the circuit connection. Usually, the contact of the same relay and the coil side are marked with the same text symbol, and the contact group is numbered to show the difference.
There are three basic forms of relay contacts:
1, dynamic closing type (normally open) (H type) coil is not energized when the two contacts are disconnected, energized, the two contacts are closed.
It is represented by the alphabetic prefix "H".
2, dynamic break type (normally closed) (D type) coil is not energized when the two contacts are closed, energized after the two contacts are disconnected.
It is denoted by the phonetic prefix "D".
3. Conversion type (Z type) This is the contact group type. This contact group has three contacts, namely the middle is a moving contact, the upper and lower one static contact. When the coil is not powered on, the moving contact and one of the static contacts is disconnected and another is closed. After the coil is powered on, the moving contact moves, so that the original disconnected into a closed state, the original closed into a disconnected state, to achieve the purpose of conversion. Such a group of contacts is called a transition contact. It is represented by the pinyin prefix "z" of the word "Zhuan".
