Consider the ladder logic program in Figure 1 and answer the following questions

Question

Consider the ladder logic program in Figure 1 and answer the following questions.

Assume both motors 1 and 2 are energized. What effect will a momentary push of input I:1/0 have on the state of the motors?

Assume both motors 1 and 2 are energized. What effect will a momentary push of input I:1/2 have on the state of motors 1 and 2?

Inputs I:1/5 and I:1/6 represent overload contacts for motor 1 and motor 2 respectively. What is the effect on the state of the motors if either one of the overload contacts opens?

Is it possible for one motor to be energized and the other motor de-energized? Explain.

Explanation / Answer

Considering above ladder logic diagram and I/O instruction set

I:1/1 and I:1/3 are normally open contacts of inputs

I:1/0, I:1/2 , I:1/4, I:1/5, I:1/6 are normally closed contacts of inputs

O:2/0 and O:2/1 are outputs and memory elements

1)

Initially, both motors are energized when input I:1/0 is push then it becomes open which de-energies both motors.

2)

Considering both motors are energized, now I:1/2 is push then motor 1 will de-energized and motor 2 will continuous in its initial state.

3)

Initially, both motors are energized when overload contacts either I:1/5 and I:1/6 are opened then both motors will stop.

4)

Yes, it will be possible to energize one motor and de-energized another motor by

pushing I:1/2 - motor 1 stops

pushing I:1/4 - motor 2 stops.

Because these two contacts are independent to each other and effects only one rung when pushed.

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