Power relays are mainly used to switch high voltage and high power loads of 3 A or higher. They are simple electrical parts comprised of a coil (electromagnet) and switch (contact). Current flows to the coil and generates a magnetic force (electromagnet) to open or close the switch automatically. Two relay types are available; contact relays and non-contact relays. For a power relay, a contact relay where a mechanical operation causes the contacts to touch is appropriate. Contact relays are also highly durable, making them ideal for power relays used for high voltage or high power applications. These relays are mainly used for devices such as factory automation equipment, industrial equipment and household equipment. These electrical parts are required in a wide variety of environments. In response to increasing demand, they have been designed to be smaller, quieter and more power-saving while maintaining their high capacity, and reliability has also been improved.