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The magnetic blowouts in the pictured Albright contactor (which is designed for DC currents) more than double the current the contactor can break, increasing it from 600 A to 1,500 A. Sometimes an economizer circuit is also installed to reduce the power required to keep a contactor closed; an auxiliary contact reduces coil current after the ...
This induced current creates an auxiliary magnetic flux which is 90 degrees out of phase from the magnetic flux created by the primary coil. [ 1 ] Frager spire or shading coil's purpose is to provide sizeable phase-shifted magnetic field (in blue) to keep the contactor on when the main coil flux (in red) passes through zero, avoiding unwanted ...
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 ...
Form X or double-make contacts are equivalent to two Form A contacts in series, mechanically linked and operated by a single actuator, and can also be described as SPST-NO contacts. These are commonly found in contactors and in toggle switches designed to handle high power inductive loads.
The braking torque depends on the magnitude of the current, which can be varied by phase control of the thyristors. When the motor is switched off, the motor contactor relay not only disconnects the AC current supply to the motor windings, but also causes a braking relay contactor to close. This initiates a sequence beginning with a time delay ...
A motor capacitor [1] [2] is an electrical capacitor that alters the current to one or more windings of a single-phase alternating-current induction motor to create a rotating magnetic field. [citation needed] There are two common types of motor capacitors, start capacitor and run capacitor (including a dual run capacitor). [2]
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.
Solid state soft starters can control one or more phases of the voltage applied to the induction motor with the best results achieved by three-phase control. Soft starters controlled via two phases have the disadvantage that the uncontrolled phase will always shows some current unbalance with respect to the controlled phases.