Final answer:
A voltage relay is a solid-state device that monitors single-phase voltage and changes output contact status when a deviation from nominal frequency is detected. It is commonly used in electrical engineering applications to protect circuits and equipment from voltage fluctuations.
Step-by-step explanation:
A voltage relay is a solid-state device that monitors a single-phase voltage and changes output contact status when a deviation from nominal frequency is detected. It is commonly used in electrical engineering applications to protect circuits and equipment from voltage fluctuations. Most voltage relays emit an audible "click" and display the voltage change on a digital or analog meter.