Which of the diagrams shown is correct for the ladder diagram with TR as an ON-Delay relay?

The correct choice is based on how an ON-delay relay functions within a ladder diagram context. An ON-delay relay is designed to energize its output after a specified time delay has passed once it receives an input signal.

In a ladder diagram for an ON-delay relay, you would typically see the normally open contact linked to the relay coil, which remains open at first. When the input signal is applied, the normally open contact closes after the delay time, allowing current to flow through the relay coil. This causes the relay to energize and activate load devices or further operations downstream.

The selected diagram accurately represents this behavior, showing the sequence of events where the input must be on for a given duration before the relay engages. This visually communicates the principles of operation for an ON-delay relay effectively, showcasing how the time delay is implemented in the control circuit.

In contrast, the other diagrams do not properly illustrate the ON-delay function or might depict immediate relay activation, which does not align with the expected behavior of an ON-delay relay. Thus, the correct diagram captures both the concept and functionality inherent in an ON-delay relay’s operation.