Electromechanical Relays

Design

The basic design of electromechanical power relays is the same regardless of whether it is a miniature PCB relay or an industrial power relay.

The most important components are:

Contact system or secondary side

• fixed contacts
• moving contacts (contacts being moved by the magnetic system (motor) to switch the load circuit)
• contact springs (holding the contacts, but sufficently flexible to allow the contacts to move)

Magnetic system

• coil (to generate necessary magnetic field to actuate the armature and the contacts)
• core
• joke (to establish the magnetic circuit)
• armature (the moving part of the magnetic system which closes and opens the magnetic circuit and acts via comb or acturator on the moving relay contacts)
• return spring (to establish a defined position of the magnetic and contact system in case the coil is not energized)