What is a timer relay and what are common types used in control circuits?

Prepare for the NCCER Electrical Level 2 Control Systems and Fundamental Concepts exam. Utilize flashcards and multiple choice questions with hints and explanations. Ensure success on your exam!

A timer relay creates a controlled time delay in a control circuit, delaying either the energizing or the de-energizing of a load after an input changes state. This lets you sequence actions, prevent nuisance or chatter from rapid changes, and give equipment time to stabilize during start-up or shut-down. In practice you’ll see two main timing actions: delay after the input is energized before the output activates (delay-on-make), and a delay after the input is removed before the output deactivates (delay-on-break). Timer relays come in electromechanical varieties, which use a small motor or clockwork and adjust the delay with a dial or preset, and solid-state varieties, which use digital circuitry to produce precise delays and often offer multiple timing ranges. Some timers also function as one-shot (produces a single pulse when triggered) or interval types (repeated pulses). These devices are chosen for control circuits to achieve proper sequencing, smoother startups, and safer, more reliable operation.