The LY4-24VAC part of Omron is an electromechanical relay module. This part is used in control circuits involving low-voltage AC power sources and provides an electrical link between two or more circuits. It is typically used in applications such as manufacturing automation, lighting controls, power and motor control. The module is rated for 4A at 24 VAC and has a one-pole, single-throw switch type. It has a life span of 200,000 operations, is UL Listed, and features a LED indicator for simple troubleshooting.