Universal relay is a kind of electrical switch device widely used in electrical control system. It controls a large current through a small current, and is used to control the switching, protection, conversion and other functions of the circuit. BFR93A general relay is mainly composed of electromagnet, contact, spring, fixed iron core and shell. Its working principle is based on the principle of electromagnetic induction.
The working principle of the general relay is as follows:
1. Electromagnet principle: the core of general relay is electromagnet, which is composed of winding and iron core. When the winding is energized, a magnetic field is generated, which acts on the iron core and forces the iron core. According to the electromagnetic principle, when the current passes through the winding, a magnetic field will form around the winding, and the direction of the magnetic field is determined by the right-hand rule. When the current flows through the winding, the magnetic field will make the ferromagnetic material on the iron core magnetized, producing attraction.
2. Contact principle: the contact of general relay is composed of a static contact and a dynamic contact. When the electromagnetic iron is energized, the iron core is forced to eliminate the gap between the moving contact and the static contact, and the contact is closed. When the electromagnet is powered off, the iron core loses magnetization, and the moving contact quickly recovers to the top of the static contact due to the spring force, and the contact is disconnected.
3. Spring principle: the spring in the general relay controls the closing and opening of the contact. When the electromagnetic iron is energized, the contact is closed due to the force on the iron core, and the spring is compressed. When the electromagnet is powered off, the contact is disconnected, and the spring force makes the contact quickly recover to the top of the static contact.
The functions of the general relay are as follows:
1. Switch function: general relay can be used to control the switch of the circuit. By controlling the on-off of the electromagnet, the circuit can be closed and disconnected, thus controlling the start and stop of electrical equipment.
2. Protection function: general relay can be used for circuit protection. For example, add an overload protection relay in the circuit. When the current in the circuit exceeds the set value, the relay will automatically disconnect the circuit to protect electrical equipment.
3. Conversion function: general relay can be used for circuit conversion. For example, adding a switching relay in the circuit can realize the switching of two circuits. When the electromagnetic iron is energized, the contact is closed and circuit A is energized; When the electromagnet is powered off, the contact opens, circuit A is powered off, and circuit B is powered on.
4. Delay function: general relay can be used to realize circuit delay. For example, adding a delay relay in the circuit can realize the delayed start or delayed break function of the circuit, thus meeting special control requirements.
To sum up, the general relay is an indispensable basic element in the electrical control system, which realizes the functions of circuit switching, protection, conversion and delay through the principle of electromagnetic induction.
