The relay coil is represented by a rectangular symbol in a circuit. If the relay has two coils, draw two parallel rectangular boxes. At the same time, mark the text symbol "J" for the relay inside or next to the rectangular box. There are two ways to represent the contacts of a relay: one is to draw them directly on one side of a rectangular box, which is a more intuitive representation. Another method is to draw each contact point into their respective control circuit according to the needs of circuit connection. Usually, the same text symbol is marked next to the contact point and coil of the same relay, and the contact group is numbered to indicate differentiation.

There are three basic forms of contacts for relays:

1. When the H-type coil is not powered on, the two contacts are open. After being powered on, the two contacts close. Represented by the pinyin prefix "H" in Chinese.

2. When the D-type coil is not powered on, the two contacts are closed, and when powered on, the two contacts open. Represent with a hyphenated pinyin prefix "D".

3. Conversion type (Z-type) This is a contact group type. This type of contact group has three contacts in total, with a moving contact in the middle and a stationary contact at the top and bottom. When the coil is not powered on, the moving contact and one of the stationary contacts are disconnected and the other is closed. After the coil is powered on, the moving contact moves, causing the previously disconnected to become closed and the previously closed to become open, achieving the purpose of conversion. This type of contact group is called a conversion contact. Use the pinyin prefix "z" of the character "Zhuan" to indicate.