Ladder diagram of sequential start and stop of conveyor belt

Explanation: This program uses a timer (T) as the control element for delayed start and stop.

The program is as follows:

Component introduction: X0 is the emergency stop button

X1, X2, X3 are thermal relays for three motors

X4 is the start button

X5 is the stop button

Y1, Y2, Y3 are motor contactors

Program description: 1. When the emergency stop and thermal relay are in the on state, the M0 auxiliary relay is powered on.

2. Press the start button X4 to turn on the signal, and the Y1 relay is powered on. Simultaneously connect T1 and T2.

3. When the delay time of T1 expires, the Y2 relay is powered on.

4. When the delay time of T2 expires, Y3 relay is powered on.

At this point, the sequential start-up of the three electric motors is completed.

5. When the stop button X5 is pressed, the signal is turned on, and the M1 auxiliary relay is powered on to control the Y3 relay to disconnect, while also turning on the T3 and T4 timers.

6. When the delay time of T3 expires, the Y2 relay will disconnect.

7. When the delay time of T4 expires, the Y1 relay will disconnect.

At this point, the three electric motors have stopped in sequence.

8. When the emergency stop button is pressed or the thermal relay is disconnected, all three motors will be powered off simultaneously.

Note: There are some unreasonable aspects in the program. Please pay attention to them and try to identify them.