What are the contact forms and symbols of Relay

Generally speaking, Relay is composed of two parts: contact and coil. Therefore, the graphic symbols in Relay circuit diagram also include two parts: a set of contact symbols represents the contact combination; and a rectangular box represents the coil; When not many circuits are relatively simple, the contact group is often drawn directly on the side of the coil frame. This drawing method is generally called centralized representation. Simple and clear, you can understand it at a glance.

When the Relay has two coils, usually draw two parallel rectangular boxes. Generally, the text symbol of Relay is marked [J] beside the rectangular box or at the appropriate position of the rectangular box. Relay contacts generally have two representation methods: one is to draw them directly on the side of the rectangular frame, which is more intuitive; the other is to draw each contact separately according to the needs of circuit connection In the respective control circuits, the same text symbols should be marked next to the contacts and coils of the same kind of Relay, and the contact group codes should also be numbered to achieve their respective differences.

The following is the basic form of Relay contacts, as follows:

1.Movable break type [normally closed] [D type]

When the coil is not energized, the two contacts are closed, and the two contacts are disconnected after energization. It is usually represented by the hyphenated pinyin prefix [D].

2.Moving and closing type [normally open] [H type]

When the coil is not energized, the two contacts are disconnected, and the two contacts are closed after energization. It is usually represented by the pinyin prefix [H] of a ligature.

3.Conversion type [Z type] contact group type

Generally, such a contact group relay has three contacts in total: the middle is a moving contact; the upper and the lower are a static contact. When the coil is not energized, the moving contact and one of the static contacts are disconnected and the other is closed. After the coil is energized, the moving contact moves to close the original open and open the original closed. Open state to achieve the effect of conversion. Such a contact group is called a changeover contact. It is represented by the pinyin prefix [Z] of the transferred character.