An electric switch in which the connecting pieces are maintained against contact surfaces in a spinning cylinder or sector by spring pressure. The switches are used to control power to various parts of an electrical circuit, such as lamps and solenoids.
There are two basic types of electric switches: magnetic and mechanical. Magnetic switches use a magnet attached to one of the connecting pieces to close a circuit when they are brought together. Mechanical switches use a lever, rocker, or other device that closes the circuit when pushed or pulled. Drum switches are a type of mechanical switch that uses a rotating wheel with openings for the three connecting pieces to slide into when closed. As the wheel turns, each opening sequentially contacts one of the connecting pieces, closing the circuit.
Drum switches were first introduced in 1902 by the Edison Electric Company and have been widely used ever since. They can be found in many modern appliances that require more than one simple switch control, such as light switches, radio volume controls, and so on.
In general usage, the term "drum switch" refers to any mechanical switch that uses a circular disk with openings for the three connecting pieces to pass through.
A switch is an electrical device, generally electromechanical, that is used to manage the continuity of two locations. Human contact activates hand switches. Machine action activates limit switches. Changes in a physical process activate process switches (temperature, level, flow, etc.). Switches are used to control power or other functions within a circuit. The term is most often applied to electro-mechanical devices used as interface elements between users and computer systems; however, it also applies to similar devices used for other purposes such as telecommunications equipment, household appliances, and industrial machinery.
Switches can be divided into two major categories: mechanical and solid state. Mechanical switches are attached to or part of the structure which controls the power, such as a wall button on a telephone system or a lever on a elevator. When the button is pressed or the lever is turned, a mechanical link connects one side of the switch to ground or +V DC, thereby closing the circuit and allowing current to flow. Mechanical switches can be further divided into three general types: dome, rocker, and slider. All three types function on the same principle, but they use different mechanisms to make this connection. A spring is usually used to restore the switch to its original position after it has been closed by the user. This prevents the need for additional circuitry to open and close the switch.
Noun The bar or rod that links a switch's moveable rails to a switch-lever on the track's side. Noun The movable bar of a switch that creates or breaks an electric circuit. Also called switch stick.
Switch bars are used in manual switches to link the moveable rail to the lever that operates the gate. They can be found in many different shapes and sizes. The most common shape is a long, thin piece of metal with one end bent back on itself to form a hook for attaching it to the moveable rail. The other end of the bar has a hole through which it fits into the switch-lever. When the rail is moved away from the fixed part of the switch, so too will the bar pull out of the hole in the lever, closing the circuit and allowing current to flow through the gate.
Manual switches using switch bars need to be maintained regularly in order to function properly. If the bar becomes rusted away from use or is otherwise damaged, it needs to be replaced. On some gates, there may be no visible sign of damage; if this is the case, check the mechanism behind the gate for signs of wear-and-tear. If it doesn't feel right, you might need to replace the bar.
Electric switches do not require maintenance.
A generally enclosed space housing the switching facilities of a power station. The term comes from the old switch houses where the main lines from various parts of the district met.
Now used mainly as a reference to a large-scale electrical substation.
The switchyard's primary duty is to transfer and distribute electricity at incoming voltage from the producing station, as well as to offer switching facilities through switchgears. The switchyard also functions as an enclosure for the distribution substations that feed power into it.
In addition, the switchyard controls the flow of traffic across its line terminals by opening and closing circuit breakers. It does this in response to signals received from central control rooms or remote electronic devices. The action of a circuit breaker may be either "on" or "off". When it is in the "on" position, current can flow through it; when in the "off" position, no current can pass. A switchyard will have several circuit breakers for different purposes. One group of circuit breakers may be used to shut off power to entire sections of the yard during major maintenance projects. Another group may function as interlocks: that is, they open the main circuit breakers if something goes wrong with the system.
Finally, the switchyard provides protection against overloading individual lines or parts of lines. If this happens, the extra current is taken by overload conductors which lead away from the yard at predetermined locations called shunts.
These are just some of the many functions of a switchyard.