The core of relay, electrical, and automation industrial equipment control mainly relies on electromagnetic induction phenomena generated by electromagnetism. In this short article, explain the working principle of relays, their main internal structural components, contact types, and coil parameters, and gain a deeper understanding of relays and related knowledge.
1. The basic mechanism of electromagnetic drive in relays
When a relay is operating normally, the current flows through its internal coil, and when the current passes through the coil, a magnetic field is formed inside the coil. The magnetic force of a magnetic field also exerts a force on the iron core. Magnetic force will attract the armature, causing it to move. The movement of the armature can drive changes in other parts, causing the contacts connected to the armature to close or open.
2, The key structural parts of relays
The relay mainly consists of wired coils, contacts, armatures, springs, frames, and casings:
Coil: is the key to generating a magnetic field, and its shape is usually made of copper wire wound. Formed by winding in circles.
Contact: In a relay, under the influence of magnetic force in a magnetic field, the switching of control contacts is achieved to connect and disconnect the contacts. In professional knowledge, contacts can be classified into normally open (NO), normally closed (NC), and switching (CO) based on their different states.
Armature: It is a component closely connected to the movable contact. When subjected to magnetic force, the armature will move accordingly, thereby driving the contact to undergo corresponding changes. This change is crucial for the relay to achieve its control function.
Spring: Ensure that the contact can return to its original position when the coil is powered off.
Frame and housing: Fix related components and protect relays from external influences.
3, Detailed explanation of contact types
Normally open (NO) contact: When there is no current passing through the relay, the contact is normally in the open state. When the relay is working and the coil current is connected, a magnetic force will be generated inside the coil to attract the armature, causing the contacts to close each other, thereby achieving the connection of the circuit.
Normally Closed (NC) Contact: The normally closed contact is in a closed state when the relay is not powered on, allowing current to flow smoothly. But once the coil receives the current, the generated magnetic force will drive the armature to move, causing the contacts to open, thereby cutting off the circuit.
Conversion (CO) contact: The conversion contact combines the characteristics of normally open and normally closed, and can switch according to the energized state of the coil. When powered on, the contacts will transition from one state to another to meet the needs of different circuits.
4, Analysis of coil parameters
The coil parameters have a crucial impact on the performance of relays. The following are several key coil parameters:
Coil voltage (V): The voltage required for the normal operation of the coil. Relays can only operate smoothly under normal voltage conditions, and high or low voltage can lead to performance degradation or damage.
Coil current (I): The amount of current flowing through the coil during relay operation. Appropriate current can ensure stable and reliable operation of the relay.
Coil resistance (R): The resistance value is an important parameter for measuring the relationship between voltage and current. Once we know the required voltage and current values, we can calculate the resistance
Coil inductance (L): Inductance measures the ability of a coil to store energy in a magnetic field. The magnitude of inductance value will affect the response speed and stability of the relay.
In summary, relays play a core role in circuit control through the principle of electromagnetic induction. Its diverse contact configuration and flexible coil parameters enable it to meet the needs of different application scenarios. A deep understanding of the basic principles and structure of relays is of great significance for optimizing electrical systems and achieving precise control.