Types of relays include electromagnetic relays, voltage relays, time relays, pressure relays, thermal relays, overvoltage relays, static voltage relays, hot wire relays, solid-state relays, and thermal reed relays.
A relay is an electrical switch that activates when its input signal meets a set threshold, triggering a corresponding change in the output circuit. It consists of a control system and an output system, and is commonly employed in automation to regulate, protect, or redirect electrical circuits.
1. Electromagnetic Relay
An electromagnetic relay is an electronic component that serves as an automated switching mechanism in control circuits. It operates by using a low-power input signal (small current and low voltage) to manage a higher-power output (larger current and higher voltage). This functionality enables it to perform tasks such as automatic regulation, circuit protection, and controlled switching in electrical systems.
2. Voltage Relay
A voltage relay is an electrical component that functions as an automatic switch in control circuits. It operates by using a low-current signal to activate or deactivate a higher-current circuit, enabling automated control and power management in various applications.
3. Time Relay
A time relay is a relay whose output circuit undergoes a sudden change after a specified, precise time interval following the application of an input signal. It is an electrical component used in circuits with lower voltages or lower currents to connect or disconnect higher voltage, higher current circuits.
4. Pressure Relay
A pressure relay is a component in a hydraulic system that activates electrical contacts when fluid pressure reaches a predetermined value. A pressure relay can also be defined as a hydraulic component that converts pressure into an electrical signal. Based on your specific pressure design requirements, you can adjust the pressure relay to output an electrical signal at a set pressure.
5. Thermal Relay
A thermal relay operates on the principle that current flowing into a thermal element generates heat, causing a bimetallic strip with different expansion coefficients to deform. When the deformation reaches a certain distance, it pushes a connecting rod, disconnecting the control circuit. This de-energizes the contactor, disconnecting the main circuit, and providing overload protection for the motor.
6. Overvoltage Relay
An overvoltage relay operates according to voltage. When the input voltage reaches a set voltage, its contacts will activate accordingly.
7. Static Voltage Relay
Static voltage relays are available in a variety of configurations, including fixed-type, plug-in-type, embedded-type, and RY-D series rail-mounted. They feature a transparent plastic cover and are adjusted using a thin gauge.
8. Hotline Relay
A hotline relay is an electrical device that switches a controlled output circuit on or off when an input quantity (such as voltage, current, or temperature) reaches a specified value. It can be categorized into two main types: relays for electrical quantities (such as current, voltage, frequency, and power) and relays for non-electrical quantities (such as temperature, pressure, and speed).
9. Solid-State Relay
A solid-state relay is a four-terminal device with two input terminals and two output terminals. An isolator is used in between to provide electrical isolation between the input and output terminals. Solid-state relays are categorized as either AC or DC depending on the load power supply type.
