For this discussion we will focus on electromechanical relays that do not have any timing functions. Electromechanical relays perform a variety of switching functions in control circuits that are found in industrial, commercial, and even residential applications. Their purpose generally is to switch or control a voltage or current with that of possibly a different voltage or current.
Electromechanical relays use a coil that is energized by an external voltage source, which will mechanically operate a set or multiple sets of contacts. The coil of an electromechanical relay may be designed to operate at a specific AC or DC voltage or may be designed to operate when a certain level of current is achieved in a series circuit. Common operating voltages are 5, 6, 12, 24, 48, and 110 VDC and 12, 24, 120, and 240 VAC. The contacts are commonly designated as form “C”, which means each set of contacts (or pole) has a common, a normally open, and a normally closed termination. Other contact configurations are available depending on requirements.
Electromechanical relay contacts are typically silver or silver with gold plating. Gold plated contacts are used in low level switching applications where extremely low contact resistance is required. Contacts in electromechanical relays can switch loads currents ranging from micro-amps or milliamps up 30 amps or so. Relays with higher current ratings are generally referred to as contactors. Many electromechanical relays have multiple sets of contacts or poles, providing greater flexibility or redundancy in numerous applications. Electro-mechanical relays may be of open or enclosed construction, may be plug-in style, or may be designed to be soldered onto printed circuit board assemblies.
One very common electromechanical relay is often called an “ice cube relay” because it has a clear cover or case and is somewhat cube shaped. Consult Eagle Signal for your electromechanical relay solutions!