Relays are basically switches that control other switches. They use a low-power signal to control a higher-power circuit. Initiating the low power signal energizes an electromagnet which moves an armature and causes electrical contacts to close, sending power to the controlled circuit.
This design effectively isolates the low-power signal from the higher-power circuit, protecting the operator from harm and equipment from damage. It also allows for the control of a device or system from a distance. Electromechanical relays have been around since 1835, and even though their components and variety have gotten more sophisticated and refined over the years, their basic function remains the same.
What are power relays?
All electrical relays control power, but not all relays are correctly termed “power relays.” To be more precise, power relays are products specifically designed to handle high-level current switching, from several amps to much higher amounts. The built-in capacity of power relay contacts to handle larger currents, coupled with their larger size and more robust coils makes power relays a good choice when switching currents of generally more than 10 amps. Some usage examples include automotive systems, elevators, valve actuators, or devices with high initial current surges, like motors, solenoids, power supplies, or electronic ballasts.
You can read the full blog, An introduction to power relays, on the Same Sky website.
