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AC contactor for pump application. A contactor is an electrically controlled switch used for switching an electrical power circuit. [1] A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit, such as a 24-volt coil electromagnet controlling a 230-volt motor switch.
When a pair of contacts touch, they can pass an electrical current with a certain contact resistance, dependent on surface structure, surface chemistry and contact time; [2] when the pair is separated by an insulating gap, then the pair does not pass a current.
Electromechanical switches, relays, and contactors “turn power on” when the moving electrode makes contact with the stationary electrode to carry current. Conversely, they “turn power off” when the moving electrode breaks contact and the resulting arc plasma stops burning as the dielectric gap widens sufficiently to prevent current flow.
They are used as high-current switches or contactors, where contact erosion from constant cycling would be a problem for conventional relay contacts. Owing to environmental considerations about the toxicity of mercury , mercury relays are mostly obsolete, though modern encapsulated units still have applications.
A magnetic starter has a contactor and an overload relay, which will open the control voltage to the starter coil if it detects an overload on a motor. [1] [2] The overload relay opens a set of contacts that are wired in series with the supply to the contactor feeding the motor.
Arc suppression is an area of interest in engineering due to the destructive effects of the electrical arc to electromechanical power switches, relays and contactors' points of contact. [11] There are many forms of "arc suppression" that provide contact protection in applications operating at less than 1 Ampere. Most of these, however, are more ...
A gas–liquid contactor is a particular chemical equipment used to realize the mass and heat transfer between a gas phase and a liquid phase. Gas–liquid contactors can be used in separation processes (e.g. distillation, absorption) or as gas–liquid reactors or to achieve both purposes within the same device (e.g. reactive distillation).
The diode is installed so that it does not conduct under normal conditions. When the external driving current is interrupted, the inductor current flows instead through the diode. The stored energy of the inductor is then gradually dissipated by the diode voltage drop and the resistance of the inductor itself. One disadvantage of using a simple ...