What is a relay?
A relay is composed of (1) an electromagnet and (2) a contact mechanism. It is defined as "a device that actuates a contact mechanism, using an electromagnetic attractive force that is generated when a current of a certain value or more flows through an electromagnet. It opens and closes a contact through voltage and current (input signal) applied to a coil."
Simply speaking, a relay receives an electric signal from a switch, etc., and transmits the signal to an output unit, such as a motor.
Relay race at a track & field day
Relays of control equipment
Relay categories
Two major categories of relays.
Control relays
Contact type
Mechanical relays
The contact opens/closes mechanically.
Non contact type
Semiconductor relays
〈PhotoMOS/Solid-state relays〉
PhotoMOS/Solid-state relaysSemiconductor contact (output section), do not opens/closes mechanically.
Relay applications
Relays are used in various machines and devices.
Digital household appliances
- Flat-panel TVs
- Video Games
Office automation equipment
- Copiers
- Multifunction fax machines
Automotive equipment
- Car navigation systems
- Anti-theft security systems
Security equipment
- Security cameras
- Alarms
- Entrance/exit monitoring systems
Household appliances
- Refrigerators
- Microwave ovens
- Washing machines
- Air conditioners
- Rice cookers
Industrial equipment
- Industrial robots
- Machine tools
- Packaging machines
Medical instruments
- Blood-pressure meters
- Ultrasonic reflectoscopes
- Nursing beds
