Question

pleaseeeeeee good handwrring and show what is A B and C again goood hand wrritingggg

1. A. The following symbols refer to the device shown in the ladder logic diagram. S1 normally open switch S2 =normally closed switch CR control relay M Motor L Indicator Light Assume that initially, the NC switch S2 has been turned OFF. Explain TO THE POINT what happens in the following instances: a. When input S1 turned ON, and then turned OFF IMMEDIATELY b. After 2 minutes, input S2 is turned ON, Explain in not more than 10 lines the function of this ladder logic circuit and a possible application for it. C. If the positions of S1 and S2 are switched (meaning that you place the S2 Switch in place of the S1 Switch and $1 Switch in place of S2 Switch) would the PLC system still function? If yes, why yes? If not, why not? HH S1 HH S3 CR $2 CR 1 HH S4 CR M L Just an answer alone will NOT suffice. You must explain your logic at each sequence before deciding the Junctionality No credit will be given if you only write the final result, even if it is

Answer 1

The explanation is as follows :

(a) It is given that the switch S2 is initially in OFF position, i.e. the switch S2 is closed. Now, when S1 is turned on the control relay CR gets activated which in turn turns ON switches S3 and S4. Now if the switch S1 is turned off immediately the relay coil still remains active since the switch S3 is in ON position (Latching). As the switch S4 is activated the motor M starts to run and the LED indicator glows, and it remains in this state.

(b) When the input S2 is turned on after 2 minutes, i.e. the switch S2 is opened, the control relay CR gets deactivated which in turn deactivates the switches S3 and S4. As the switch S4 is deactivated, the motor stops running and the LED stops to glow. Thus the entire system is deactivated.

(c) The function of this logic circuit is to activate an output ( in this case a motor) for a certain period of time after which it is deactivated. This logic circuit can be used to run the motor of a pump which is used to fill up a tank. To start the process switch S1 is pressed and released, then after the tank has been filled up switch S2 is pressed and the entire process is stopped.

Now if the positions of S1 and S2 are interchanged, the system will not work it's intended function. This is because when the switch S1 is pressed the control relay CR will be activated along with switches S3 and S4 but when it is immediately turned OFF the control relay CR will immediately get deactivated in turn deactivating switches S3 and S4. Thus the motor will start running for a moment and then stop immediately.