DC electromagnet is an electrical appliance that uses the electromagnetic attraction generated by the current-carrying iron core coil to manipulate the mechanical device to complete the desired action. It is an electromagnetic component that converts electrical energy into mechanical energy. It is widely used in automatic control mechanical transmission systems, and can be used as a type of electrical appliances alone, such as traction dc electromagnet, braking dc electromagnet, lifting dc electromagnet, etc., and can also be used as a component of switching electrical appliances, such as contactors, relays Electromagnetic system, electromagnetic release of circuit breaker, etc.

DC electromagnet is mainly composed of three parts: coil, iron core and armature. The iron core and armature are generally made of soft magnetic materials. The iron core is generally stationary, and the coil is always mounted on the iron core. The armature of the dc electromagnet of the switching appliance is also equipped with a spring.
There are many structural forms of dc electromagnet. According to the form of the magnetic circuit system, it can be divided into click type, disc type, E type and solenoid type. According to the movement mode of the armature, it can be divided into rotary type and direct-acting type. Different structure forms, different working characteristics of dc electromagnet, and different applicable occasions.
When the coil of the dc electromagnet is not energized, the armature maintains a relatively large air gap with the iron core under the action of the spring, and the armature is in the release position. When the coil is energized, under the action of the magnetomotive force of the coil, a magnetic field is established to generate magnetic flux, most of which pass through the closed loop formed by the iron core and the armature. At this time, the core and the armature are magnetized, called two magnets with opposite polarities, and electromagnetic attraction is generated between them. When the suction force is greater than the reaction force of the spring, the armature begins to move toward the iron core, and at the same time, the armature can drive other mechanical devices or components to complete the expected automatic action. When the current in the coil is less than a certain value or the power supply is interrupted, the electromagnetic attraction force is less than the reaction force of the spring, and the armature will return to the original release position under the action of the reaction force. This is the basic working principle of dc electromagnet.