A relay is an electrical control device that has an interactive relationship between the control system (also known as the input loop) and the controlled system (also known as the output loop). Usually used in automatic control circuits, it is actually an "automatic switch" that uses a small current to control the operation of a large current. Therefore, it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit.

Electromagnetic relays are generally composed of iron cores, coils, armatures, contact reeds, etc. As long as a certain voltage is applied to both ends of the coil, a certain current will flow in the coil, resulting in an electromagnetic effect, and the armature will overcome the pulling force of the return spring and attract to the iron core under the action of electromagnetic attraction, thereby driving the armature. The moving contact and the static contact (normally open contact) are pulled together. When the coil is powered off, the electromagnetic suction also disappears, and the armature will return to the original position under the reaction force of the spring, so that the movable contact and the original static contact (normally closed contact) are released. In this way, the suction and release are achieved, so as to achieve the purpose of conducting and cutting off in the circuit. For the "normally open and normally closed" contacts of the relay, it can be distinguished as follows: the static contacts that are in the open state when the relay coil is not energized are called "normally open contacts"; the static contacts that are in the connected state are called "normally open contacts". It is a "normally closed contact". A relay generally has two circuits, a low-voltage control circuit and a high-voltage working circuit.

   Ningbo Helishun Electron Co.,Ltd. is founded in 2000, located at Ningbo City, the Grand East port on the coastline of the East Sea.Now it cover 8800 square meters. It is specialized in researching ,developing and producing relay,and plays an important role in the relay market.. It's registered trade mark is
   The company introduced advanced technology and advanced testing equipment from home and abroad, and had built up dependable quality managing system.It has passed ISO9001: 2015 quality system certification. The characteristics and mounting layout of the products are kept accordant with foreign congeners.The company's products have gained the certificates of UL,TüV,CE and CQC, and comply with EU requirement of RoHS.It is a priority to replace similar products choice. "HELISHUN" relays are well sold in home and abroad market, and are widely used in household electrical appliance, telecommunication, automation control, automobile, instrument and meters.