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What is the principle of electrical control?
I work in a power plant, and my electrical drawings can generally be divided into the following categories:

1, system diagram or block diagram: used to roughly represent the basic composition, interrelationships and main features of the system;

2. Circuit diagram: it is an electrical schematic diagram, explaining the working principle of the whole circuit;

3. Wiring diagram. Including various terminal numbers, etc. , mainly used for wiring installation and circuit maintenance;

4. Location map: the specific location of each component used when installing components;

5. Logical diagram: binary logical symbols are used to represent logical relationships;

6. Function diagram: This diagram is similar to the flow diagram of PLC and expresses the control flow.

If you still don't understand, for example:

As shown in the above figure, this is a typical electrical schematic diagram of contactor interlock positive and negative rotation control of three-phase asynchronous motor. In order to ensure that one contactor can't be electrified and avoid short circuit between power supply phases, the normally closed auxiliary contact of the reverse contactor KM2 is connected in series in the forward control loop, and the normally closed auxiliary contact of the forward contactor KM 1 is connected in series in the reverse control loop. When contactor KM 1 is energized, the normally closed contact of KM 1 connected in series in the reverse control loop is disconnected, and the reverse control loop is cut off to ensure that the main contact of KM 1 cannot be closed when it is closed. Similarly, when the contactor KM2 is energized, the normally closed contact of KM2 is disconnected, and the forward rotation control circuit is cut off, thus reliably avoiding the short circuit accident of two-phase power supply.

Simply put, in the schematic diagram, you can see which switches, which devices act, and how each device works in harmony.