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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.
The current rating of smaller NEMA contactors or their auxiliaries are defined by NEMA ICS 5: Industrial Control and Systems, Control Circuit and Pilot Devices [1] standard. The nomenclature is a letter followed by a three-digit number, the letter designates the current rating of the contacts and the current type (i.e., AC or DC) and the number ...
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.
Solid-state relays have no moving parts. 25 A and 40 A solid state contactors. A solid-state relay (SSR) is a solid state electronic component that provides a function similar to an electromechanical relay but does not have any moving components, increasing long-term
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 ...
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 ...