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this is three phase asynchronous motor positive and reverse relay contactor
control operation circuit
KM1 for the motor to run the AC contactor,KM2 for the motor reverse running
AC contactor,SB2 is the positive turn button,SB3 to reverse the start
button,SB1 for stop button,FR for thermal protection relay.
When the SB2 is pressed,KM1 coils pull,KM1 main contact closure,The motor
begins to run forward,At the same time the KM1 auxiliary normally open
contacts and the KM1 coil power pull,The positive continuous operation of the
motor is realized,Press the stop button until SB1;On the contrary, when the
SB3 is pressed,KM2 coils pull,KM2 main contact closure,The motor begins to
run in reverse,At the same time the KM2 auxiliary normally open contacts and
the KM2 coil attracting, the motor reverse continuous operation,Press the
stop button until SB1;KM1, KM2 coil interlock to ensure that the power is not
at the same time,The research of this task uses PLC to realize the positive and
reverse PLC control of the three-phase asynchronous motor.
Positive inversion control circuit of motor
The external hardware output circuit using KM2, KM1 normally closed
contacts to the mutual lock.

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PLC wiring diagram
Program 1,
Start – protection – stop instructions
Ladder diagram Instruction list
X002 series in forward running the branch normally closed contacts and Y001
normally closed contact, run in reverse branch X001 normally closed and
Y000 series of normally closed contacts to realize the buttons and the
contactor interlocking

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Program 2,
Set / reset instructions
Ladder diagram Instruction list
Program 3,
Stack operation instructions

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Ladder diagram Instruction list
Debugging
① input program.
②static debug When pressed forward the start button SB2, YO bright
press the stop button SB1, Y0 off;
When you press the start button reverse SB3, Y1 bright, press the stop
button SB1, Y1 off;
When you press the start button SB2 forward when, Y0 on, press the start
button SB3 when reversing, Y0 off, while Y1 bright, press the stop button SB1,
Y1 off
③Dynamic debugging. When you press the forward button KM1, the SB2
is closed,
Press the reverse button to start SB3, KM1 off, while KM2 closed; press the
stop button SB1, KM2 off