results and discussion (plc)

8/10/2019 Results and Discussion (PLC)

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RESULTS AND DISCUSSION

Exercise 1A: Controlling Lamps by Toggle Switches

(i) What happens when switch 1 is activated?

Lamp Q 0.0 did not light up. When only switch 1 was being switched on and switch 2 was

still switched off, the current would not be able to travel through switch 2, therefore no

current was supplied to the lamp Q 0.0 and it would not light up.

(ii) What happens when switch 1 & switch 2 both are activated?

The lamp Q 0.0 lighted up. Since both switch 1 and switch 2 were switched on, there was

current supplied to the lamp Q 0.0.

(iii) Discuss the difference between rung 1 and rung 2.

In rung 1, the switches are acting as AND gate configuration and they are connected in

series. Both switches have to be switched on to produce an output and current is able to be

supplied to the lamp Q 0.0. In rung 2, the switches are acting as OR gate configurations

and they are connected in parallel. When either one of the switches is switched on, it is able

to produce an output and current is able to be supplied to the lamp Q 0.0.

(iv) Discuss the condition to see light in the second lamp (Q 0.1) if the input I 0.3 is replaced

by Q 0.0.

If both switches of I 0.0 and I 0.1 were switched on, the second lamp was able to light up as

the current was able to pass through Q 0.0 and triggered the lamp Q 0.1 to light up.


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Exercise 1B: Controlling an Electric Motor by Push Buttons and Overload Relay

(i) What happens when Start Pushbutton is activated?

Lamp Q 0.0 lighted up as there was a continuous current output supplied to Q 0.0 because of

the OR gate configuration. Both NC switches I 0.1 and I 0.2 allow the flow of current and

activated the motor to start.

(ii) Discuss the effect of having the Stop Pushbutton.

The effect of having the Stop Pushbutton is to cut off the current flow to trigger the motor.

The normally closed (NC) pushbutton allowed the current flowing through to trigger the

motor at the beginning therefore by having the Stop Pushbutton we were able to stop the

operation of the motor.

(iii) Is it possible to sustain continuous output if the input elements I 0.0 and I 0.1 are

interchanged?

There would not be continuous output current supply to the motor. Since I 0.0 is normally

open (NO) switch while I 0.1 is normally closed (NC) switch, when their position was

interchanged the I 0.0 blocked the flow of current.

(iv) What is the effect of having an overload relay?

The function of an overload relay is to cut off the current flow in the circuit when there is an

excessive flow of current. Here it is in placed to ensure the safety of the motor starter during

emergency.


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Exercise 1C: Controlling a Pilot Light by Timers

(i) What happens when Start Pushbutton is activated?

The lamp Q 0.1 lighted up after a delay of 15 s due to the activation of the T37 timer which

had been set at PT=150, therefore it took 15 s delay before the timer T37 is triggered toproduce an output.

(ii) Discuss the effect of having the Stop pushbutton.

The Stop Pushbutton is able to allow the current to flow through it and to cut off the

flow of current in the circuit when it is pushed.

(iii) Is it possible to sustain continuous output if the input elements I 0.0 and 10.1 are

interchanged?

It is not possible to sustain a continuous output as the input element I 0.0 is a normally open

(NO) switch, current will not be able to flow through it without being activated.

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