E3RA-DP21 is a time relay manufactured by Omron. It is a single-pole double-throw (SPDT) type relay with a built-in timer, capable of providing a switching time between 1 second and 30 minutes with a rating of 10A at 250V AC. This relay has a standard DIN rail or socket mountable design, allowing for easy installation. It is designed to be used as a timer for applications such as control of lights, pumps, motors, or other output devices.