Before purchasing an electrical relay, it is important to understand its specifications. Relays have various contacts made of different materials that are necessary to operate efficiently. The main problem associated with relay contacts is pitting, which occurs when material builds up in the center of the contact. This results in sparks and can damage the relay. The solution is to use a shading coil to prevent the contact from chattering.

Another type of electrical relay is a vacuum relay, which has an unusual external design. Its shape resembles a measuring instrument or a vacuum tube. Its mechanism is based on a combination of the magnetic field and an electric current. The input part of a vacuum relay is wound on a rectangular light aluminum tube, which is placed in a gap between an iron core ring and a permanent magnet.

Relays are important electrical devices that have a wide variety of applications. Some of the most common uses include appliances, telecommunication systems, and power distribution centers. They can be used for a wide range of functions, including switching, motor protection, and detecting circuit faults. They can be used in a single or multiple circuits.

Electromechanical relays are easy to use and inexpensive, but have many disadvantages. They are bulky and slow, and their contacts are prone to arcing and erosion. Moreover, they are electrically noisy. They also suffer from contact bounce, which means that they do not switch very fast.