How does a basic reed relay switch a circuit using magnetic fields?
1 Answer
A reed relay is an electromechanical switch that operates using the interaction of magnetic fields. It consists of two main parts: a reed switch and a coil. Here's how a basic reed relay works to switch a circuit using magnetic fields:
Reed Switch: The reed switch is a small, hermetically sealed glass tube containing two thin, flexible metal strips (called reeds) that are in close proximity but do not touch each other. The metal used for the reeds is often ferromagnetic, meaning it can be magnetized.
Coil: The coil is a wire wound around the glass tube that contains the reed switch. When current flows through the coil, it generates a magnetic field around it.
Operation:
Normally Open Configuration: In its normal state, the reed switch is open, meaning the two reeds are not touching, and the circuit is not completed.
Application of Current: When current flows through the coil wound around the glass tube, a magnetic field is generated around the coil.
Magnetic Attraction: The magnetic field generated by the coil magnetizes the ferromagnetic reeds within the glass tube. This causes the reeds to be attracted to each other, overcoming their natural spring-like tension.
Contact Closure: As the reeds are drawn together by the magnetic attraction, they make physical contact with each other, closing the circuit that is connected to the reed relay's terminals. This completes the circuit and allows current to flow through the switched circuit.
Release:
Removal of Current: When the current through the coil is turned off, the magnetic field disappears, and the reeds lose their magnetization.
Spring Action: The inherent spring tension of the reeds causes them to return to their original, non-contacting position due to their flexibility.
Contact Opening: As the reeds move apart, the circuit is broken again, and the current flow in the switched circuit is interrupted.
Reed relays are commonly used in applications where isolation between the control circuit (coil side) and the switched circuit (contact side) is required, or where fast switching speeds and minimal contact resistance are important. They are often used in areas like telecommunications, industrial control systems, and automation.
Keep in mind that while this explanation covers the basic operation of a reed relay, there are different types and variations of reed relays that might have additional features or modifications.
Reed Switch: The reed switch is a small, hermetically sealed glass tube containing two thin, flexible metal strips (called reeds) that are in close proximity but do not touch each other. The metal used for the reeds is often ferromagnetic, meaning it can be magnetized.
Coil: The coil is a wire wound around the glass tube that contains the reed switch. When current flows through the coil, it generates a magnetic field around it.
Operation:
Normally Open Configuration: In its normal state, the reed switch is open, meaning the two reeds are not touching, and the circuit is not completed.
Application of Current: When current flows through the coil wound around the glass tube, a magnetic field is generated around the coil.
Magnetic Attraction: The magnetic field generated by the coil magnetizes the ferromagnetic reeds within the glass tube. This causes the reeds to be attracted to each other, overcoming their natural spring-like tension.
Contact Closure: As the reeds are drawn together by the magnetic attraction, they make physical contact with each other, closing the circuit that is connected to the reed relay's terminals. This completes the circuit and allows current to flow through the switched circuit.
Release:
Removal of Current: When the current through the coil is turned off, the magnetic field disappears, and the reeds lose their magnetization.
Spring Action: The inherent spring tension of the reeds causes them to return to their original, non-contacting position due to their flexibility.
Contact Opening: As the reeds move apart, the circuit is broken again, and the current flow in the switched circuit is interrupted.
Reed relays are commonly used in applications where isolation between the control circuit (coil side) and the switched circuit (contact side) is required, or where fast switching speeds and minimal contact resistance are important. They are often used in areas like telecommunications, industrial control systems, and automation.
Keep in mind that while this explanation covers the basic operation of a reed relay, there are different types and variations of reed relays that might have additional features or modifications.