An example of memory logic by a control relay is

• A. Latching relay
• B. Seal-in circuit
• C. Time-delay circuit
• D. Debounce circuit

Answer: (B)

Memory in control relay logic means the circuit can keep its output on even after the initiating input is released. A seal-in circuit shows this clearly by using a holding contact of the same relay to maintain coil current once energized. When you press the start command, the coil energizes and its normally open holding contact closes, creating a path that bypasses the start switch. Because that holding contact stays closed while the coil remains energized, the relay stays on after the start button is released. To turn it off, an explicit stop input (or a normally closed stop path) breaks the hold path and de-energizes the coil.

This setup is the classic example of memory logic with a control relay: the relay “remembers” that it was turned on by keeping itself energized through its own contact. The other options involve functions (delaying, debouncing, or a separate latching device) that don’t illustrate holding the on state through the relay’s own feedback in the same way.