We tend to take our electricity supply for granted and assume it is always available at the flick of a switch as it were. In a way, this is understandable since power outages are few and far between but, it is unfortunate that few of us ever look beyond the switch or electric power outlet socket. Maybe we have a vague idea about the meaning of terms like voltage and current and we know that they can be dangerous and need to be kept under control. Those of us with heavier electrical equipment such as large air conditioners or swimming pool pumps will have, at least, noticed that these require something a lot different from a domestic light switch to turn them on.
Controlling The Flow Of Electricity
Electricity is generated by the power company and is the flow of electrons through wires to wherever it is required. Voltage can be likened to the difference in height that makes water flow downhill and current is the rate of flow. Power is the work done by the electricity.
Obviously, powering a light bulb needs less electrical power than that required to drive our swimming pool pump. It follows from this that the switches and circuitry for the light bulb will be different than that required for the pump motor. Apart from protection against overloading a circuit, many applications also require that the power does not get instantly applied. Electric starters, circuit breakers, relays and contactors are parts of an electricity supply system that control the way in which the electricity flows. Transformers and rectifiers on the other hand control the amount and type of power available for use.
Contactors And Relays
The term “contactor” is used in an electrical context to denote a device that is similar to a relay but mainly used on higher current ratings. It is essentially an electrically operated switch. Contactors have a lower powered circuit that controls the switching of the higher powered circuit needed to perform the task in hand. They come in many different sizes and power ratings and, unlike a circuit breaker they are not designed to specifically trip out under a power surge.
Many contactors – such as those produced as Authorized Parts Products Unlimited Contactors – utilize a coil acting as an electromagnet to close the contacts on the high current side of the device. When supply to the low current circuit is stopped, the high current contact is opened. This will often be assisted by release of a compressed spring mechanism.