The most common types of relays are standard instantaneous control, latching, and timing. Contactors and starters can be considered common types of heavier duty relays with and without load protection. Standard Instantaneous Control Relays Standard instantaneous control relays are electromechanical or solid state. Electromechanical control relays use a magnetic coil and armature to cause contacts to open or close when current is applied to the coil. Relays are typically used to switch AC and DC control signals with voltages from 0 to 600 volts and typically have contact ratings of less than 20 amps.
Control relays come in numerous sizes and shapes.
Latching relays may have mechanical latches using a set and reset coil, or they may latch magnetically. Latching relays are also available with manual reset latches. Numerous other configurations are available. Contactors and Starters Contactors are essentially large capacity relays specifically designed to control the flow of electrical power to electrical loads, such as motors, heaters and lights. Contactors are multi-pole devices typically arranged to interrupt all energized conductors serving an electrical load, thus removing all voltage from the load.