Introduction to Industrial Automation

diagram of Figure 4.16.

---

Logical Design of Automation Circuits 

◾

 

133

4.3.4   State Diagrams with Time Relays

In cases where the automation application contains the parameter of time, as analyzed in Chapter 3, 

one or more time relays (timers) should be utilized, depending on the application needs. In this 

case the introduction of a time relay in a state diagram should follow the next additional design 

principles:

  1. Every time relay should be considered as a common relay, and should represent a state of the 

system.

  2. The output contact of the time relay that is going to be energized with a time delay should 

be considered as the signal that will cause the transition of the system from one state into 

another one.