Question

how to do the problem 3?

PROBLEM 3 VDC Gnd CR1 Fill valve HE Drain valve Start switch 120 VAC Gnd Off On On cycle relay CR1 Inlet flow switch Mixer motor contactor Temperature switch Heater contactor System on CR1 HA Figure 5: Problem 3 Ladder Logic Diagram 1. Create a table of inputs and outputs for the system (see Table 1). 2. Give each input and output a simplified variable name (ex. SW1). 3. Determine the boolean expression for each output device (see Figure 2). 4. Create a truth table for each output device (see Table 2).

Answer 1

Question 3:

Here inputs are:

Let, Start switch= A

Inlet flow switch=B

Temperature switch = C

The output devices are:

Let,

Fill valve = U

Darin valve = V

Mixer motor = X

Heater = Y

System ON indicator lamp = Z

Boolean expression for Fill valve(U):

When CR1 NO contact is closed, fill valve energises. And CR1 become closed when, Start switch(A) is turned ON

So, U=A

Boolean expression for Darin valve (V):

When start switch is OFF condition, Drain valve energises.

So, V=$\bar{A}$

Boolean expression for Mixer motor (X):

When inlet flow switch(NO contact) is closed, mixer motor contactor energises and the mixer motor starts.

So, X=B

Boolean expression for Heater (Y):

When the NC contact of temperature switch(C) is in de energised condition( closed condition) and CR1 is in closed condition(that means start switch is in ON condition), then the heater contactor gets energised.

So, Y= A.$\bar{C}$

Boolean expression for System ON indicator lamp(Z):

When NO contact of CR1 is in closed condition(that means start switch is in ON condition), then the System ON indicator lamp gets energised and lamp turned ON.

So, Z= A