# Understand these 6 circuit diagrams, it is not difficult to get started in industrial control

Many beginner friends don’t know how to analyze circuit diagrams. Today, the editor will select a few classic cases to explain them one by one. As long as you thoroughly learn these circuits, you can slowly learn to design circuits by yourself. The advanced electrician exam will give a circuit diagram, as long as you can analyze the circuit diagram and look at the wiring diagram.

Many beginner friends don’t know how to analyze circuit diagrams. Today, the editor will select a few classic cases to explain them one by one. As long as you thoroughly learn these circuits, you can slowly learn to design circuits by yourself. The advanced electrician exam will give a circuit diagram, as long as you can analyze the circuit diagram and look at the wiring diagram.

Star Delta buck start

This is a wiring diagram for manual control. You must pay attention to the phase sequence for the wiring of the main line. The star connection of the motor is used when starting, and the delta connection is used when running. On the control line on the right, KMY and KM△ must be interlocked. After the start button SB2 is pressed, KM is always in the self-locking state. After a few seconds delay, we manually press SB3. At this time, the KMY coil is de-energized and KM△ is automatically locked. Lock. SB3 button switch normally open point string KM△ coil normally closed point string KMY coil.

This is a star triangle with a delay relay

The star-delta with delay relay is more convenient. The wiring is similar to the manual control in the above figure, except that the button switch is replaced with a delay relay. After the button switch SB2 is pressed down, KM1 locks itself, and the coil of the delay relay is energized to start. The delay relay KT normally closed point is stringed with KM2 coil, and KT normally opened point is stringed with KM3 coil. After the delay time is up, KM3 locks itself. The auxiliary normally closed point of KM3 is in series with the coil of the delay relay, so after the start is completed, the delay relay will also be de-energized.

Control motor forward and reverse complete wiring

This circuit is used a lot, in fact, it is the combined application of contactor self-locking and interlocking. The coils of KM1 and KM2 are connected to each other’s auxiliary normally closed points respectively. In general practical applications, the two buttons SB2 and SB3 should also be mechanically interlocked. Double interlocking is more secure.

One-key start and stop

This circuit is not very practical, but it is very suitable for learning. Two intermediate relays and an AC contactor, let’s look at the circuit, the two relays are interlocked, the auxiliary normally closed point of the coil string KM of KA1, and the auxiliary normally open point of the coil string KM of KA2. Therefore, pressing the SB button switch KA1 self-locking, and at the same time the normally open point of KA1 closes the KM self-locking, realizing the start operation. Then press the SB button switch, KA2 will self-lock again, the normally closed point of KA2 will be disconnected, and the normally closed point of KA2 is the string of KM coils, so at the same time the KM coil is de-energized to stop the operation.

Trolley automatic shuttle circuit

This circuit is also very classic. In fact, it is an enhanced version of controlling the forward and reverse rotation of the motor. Use the travel switch to achieve the effect of automatic reciprocating, press the SB1 start button KM1 to self-lock, the trolley starts to move forward, when it touches the limit switch SQ1, the KM1 coil loses power and KM2 self-locks, and the trolley runs in the reverse direction. As long as the stop button SB3 is not pressed, it will run in a loop.

Star triangle plus forward and reverse

I have analyzed the star triangle in the above picture, and also analyzed the control of the motor’s forward and reverse rotation. The two pictures are merged into one, which is the picture, and friends who like it can learn to analyze it by themselves.