Electric current relays work in conjunction with switches and are used to power electronic gadgets by starting them or stopping them (turning them on or off). Electricians use different types of relays to accomplish specific kinds of tasks, however, all relays have common factors that dictate their ability to function. This principle requires use of a load circuit and a control circuit for each relay.
A primary factor that allows relays to work is the position of the pins associated with each particular relay's load switch. The pins, that are built-in to their relay load switches, consist of two separate pieces that sit opposite one another. Some load switches have pins that remain open when not in use. Other load switches contain pins that remain closed when not being utilized. Whether relays utilize pins that are at rest in opened positions or in closed positions their principle operation is the same except that one type works in an opposite fashion than the other. How relays work utilizing switches that are at rest in the open position will be discussed here.
Load circuits contain the pins (switches) that open or close depending on the position of their control circuits. When a control circuit is powered on its load circuit switch closes. Conversely, when a control circuit is powered off its load circuit switch opens. When load circuit switches close or open they energize or de-energize relays, respectively. Whether a relay is energized or de-energized determines whether or not electric currents flow to their intended sources.
Control circuits contain coils that are used to operate load circuit load switches. The way coils control the switches is by using electricity to produce magnetic fields. The magnetic field generated in a coil causes the switch in the load circuit to close. When the switch, closes, it fills a gap by connecting its two pins so that electricity can flow through both of them. Allowing an electric current to flow through both pins rather than stopping it after it reaches one pin causes the load switch to operate.
When the current flows through both pins in a switch, the gadget connected to the switch begins to work, or is powered on. In order to stop the gadget, or power it off again, the current must be interrupted by preventing the coil from generating the magnetic field. Once the magnetic field produced in the coil stops sending electricity to the switch, the switch opens up again, forming the gap between the pins that prevents electricity from flowing to the gadget.
Relay switches are often smaller than the gadgets they are used to operate such as a computer or a light bulb. The job they perform is immense, however, since without them humans would be at a loss for turning on the washer, dryer, stereo and so many other manmade gadgets they often take for granted.