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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.
Single-pole circuit breakers feed 120 V circuits from one of the 120 V buses within the panel, or two-pole circuit breakers feed 240-volt circuits from both buses. 120 V circuits are the most common, and used to power NEMA 1 and NEMA 5 outlets, and most residential and light commercial direct-wired lighting circuits.
Phasor diagram showing 240 V delta and center-tapped phase (a–c) creating two 120 V pairs. Consider the low-voltage side of a 120/240 V high leg delta connected transformer, where the b phase is the high leg. The line-to-line voltage magnitudes are all the same: = = =.
A mercury relay (mercury displacement relay, mercury contactor) is a relay that uses mercury as the switching element. They are used as high-current switches or contactors , where contact erosion from constant cycling would be a problem for conventional relay contacts.
Wire crossover symbols for circuit diagrams. The CAD symbol for insulated crossing wires is the same as the older, non-CAD symbol for non-insulated crossing wires. To avoid confusion, the wire "jump" (semi-circle) symbol for insulated wires in non-CAD schematics is recommended (as opposed to using the CAD-style symbol for no connection), so as to avoid confusion with the original, older style ...
A simplified schematic diagram of a power system. on-premises wiring Telecommunications wiring owned by the customer. open-circuit test A test, of a transformer or other device, with no load connected. open-circuit voltage The voltage developed at the terminals of a device with no load connected. open-circuit time constant method
An electromagnetic relay with a pair of contacts. An electrical contact is an electrical circuit component found in electrical switches, relays, connectors and circuit breakers. [1]
A contactor is a heavy-duty relay with higher current ratings, [21] used for switching electric motors and lighting loads. Continuous current ratings for common contactors range from 10 amps to several hundred amps. High-current contacts are made with alloys containing silver.