The YP15A and THC15A are both microcomputer-controlled timer switches, commonly used for controlling electrical devices on a specific schedule. These switches are typically installed on a 35mm rail. The YP15A timer switch offers programmable on/off timing for devices connected to it. It allows users to set specific time intervals for devices to be turned on and off automatically. This is useful for applications such as lighting control, power-saving features, or automation purposes. The THC15A timer switch operates similarly to the YP15A but may have slightly different features or capabilities. It also provides programmable timing options, allowing users to set specific schedules for devices to be powered on or off. Both the YP15A and THC15A timer switches are small, compact, and suitable for various electrical control applications. They are commonly used in home automation systems, lighting control systems, industrial control panels, and other automation setups. It is important to consult the manufacturer’s instructions or user manual for proper installation and programming of these timer switches. This ensures that they function correctly and meet the specific requirements of your application.