What is an electromagnetic relay? Working characteristics of electromagnetic relays

What is an electromagnetic relay? Working characteristics of electromagnetic relays
Electromagnetic relay is an electronic control device that has a control system (also known as input circuit) and a controlled system (also known as output circuit). This control device is usually used in automatic control circuits, which use smaller current and lower voltage to control large current and high voltage "automatic switches". Therefore, it plays a role in automatic adjustment, safety protection, and conversion circuit in the circuit.
Electromagnetic relay (electronic relay)
Electromagnetic relays are generally composed of electromagnets, armature, spring plates, contacts, etc. The working circuit consists of a low-voltage control circuit and a high-voltage working circuit. Electromagnetic relays can also achieve remote control and automatic control. As long as a certain voltage is applied to both ends of the coil, a certain amount of current will flow through the coil, generating electromagnetic effects. Under the attraction of electromagnetic force, the armature will overcome the rebound force and attract the iron core, thereby making the moving contact (normally open contact) of the magnetic core attract the magnet. Once the coil loses power, the electromagnetic attraction also disappears, and the armature will return to its original position under the reaction force of the spring, releasing the moving contact from the original static contact (normally closed contact). In this way, suction and release are achieved to achieve the purpose of conduction and disconnection in the circuit. For the normally open and normally closed contacts of a relay, the static contacts that are in the disconnected state when the relay coil is not energized can be called normally open contacts; The static contact in the connected state is called a "normally closed contact".
Thermal reed relay
Thermal reed relay is a new type of thermal switch that uses thermal sensitive magnetic materials for temperature detection and control. The device consists of temperature sensing magnetic ring, constant magnetic ring, reed tube, thermal conductive mounting plate, plastic substrate and other accessories. The thermosensitive reed relay does not use coil excitation, but is driven by magnetic force generated by a constant magnetic ring to operate the switch. The ability of the constant magnetic ring to provide magnetic force to the reed tube depends on the temperature control characteristics of the temperature sensing magnetic ring.
Solid state relay (SSR)
A solid-state relay consists of a four terminal device with two terminals as input and the other two terminals as output, with an isolation device used in the middle to achieve electrical isolation between input and output.
Solid state relays can be divided into two types based on the type of load power supply: AC and DC. According to the type of switch, it can be divided into normally closed and normally closed. According to the isolation type, it can be divided into hybrid type, transformer isolation type, and photoelectric isolation type, with photoelectric isolation type being the main type.
Solid state relays are a branch of relay products that use semiconductor devices to replace traditional coil manufacturing, without relying on the movement of mechanical components to control the opening and closing of switches, effectively improving reliability and service life. Because there is no need to wrap around, there will be no electromagnetic interference or contact with sparks, which greatly improves safety. Solid state relays have low power and are more suitable for high-end products, meeting national energy-saving and environmental protection requirements.
Nominal operating voltage.
The voltage required by the coil when the relay is working properly. It can be AC voltage or DC voltage, depending on the model of the relay.
Direct resistance.