Contactors are heavy-duty electromagnetic switches that are normally used in controlling large lighting loads and motors. They operate similar to relays, but often times deal with more voltage, higher amperage, and have more input and output options.
Category: Automatic Devices
The Kelvin Scale is used to talk about color of objects at certain temperatures, whereas other temperature scales deal with actual heat or thermal temperature. Kelvin is used in lighting especially for that reason, to talk about the color of light emission.
A relay is a type of electromagnetic switch, similar to a contactor, that can be controlled remotely with electricity, rather than needing manual input as a standard switch would.
A lot of people get really confused by contactors and relays and tend to treat them like some kind of mystical magic device without understanding what exactly they do. They have some similarities but still have very distinct differences.