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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.
Mercury relays consist of a vertical (usually glass) tube containing liquid mercury. They have isolated contacts at the bottom of the tube and partway up, usually in a side arm of the glass. The relay works by displacement. A pool of mercury fills the lower portion of the tube, but is insufficient to bridge the contacts.
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. When the contacts touch, the switch is closed; when the contacts are separated, the ...
Solid state relay with green LED Solid state contactor PCB mount solid-state DIL relay. A solid state relay (SSR) is an electronic switching device that switches on or off when an external voltage (AC or DC) is applied across its control terminals.
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. The characteristics of the heaters can be matched to the motor so ...
Continuous current ratings for common contactors range from 10 amps to several hundred amps. High-current contacts are made with alloys containing silver. The unavoidable arcing causes the contacts to oxidize; however, silver oxide is still a good conductor. [22] Contactors with overload protection devices are often used to start motors. [23]
An electronic power contact arc suppressor attached in parallel across the contact of a relay or contactor (Fig. 1 of issued patent U.S. 8,619,395 B2) The circuit diagram is part of an issued patent for an electronic power contact arc suppressor intended to protect the contacts of electrical relays or contactors. It suppresses arcs by providing ...
This would be hazardous for the operator. For this reason, many European, American, national and international norms and safety standards prohibit the use of simple relays or contactors on hazardous machines. [9] The typical design of a first-generation safety relay is based on the classic three-contactor combination.