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Magnetic reconnection is a breakdown of "ideal-magnetohydrodynamics" and so of "Alfvén's theorem" (also called the "frozen-in flux theorem") which applies to large-scale regions of a highly-conducting magnetoplasma, for which the Magnetic Reynolds Number is very large: this makes the convective term in the induction equation dominate in such regions.
The contacts are usually normally open, closing when a magnetic field is present, or they may be normally closed and open when a magnetic field is applied. The switch may be actuated by an electromagnetic coil, making a reed relay, [2] or by bringing a permanent magnet near it. When the magnetic field is removed, the contacts in the reed switch ...
Magnetic field (green) induced by a current-carrying wire winding (red) in a magnetic circuit consisting of an iron core C forming a closed loop with two air gaps G in it. In an analogy to an electric circuit, the winding acts analogously to an electric battery, providing the magnetizing field , the core pieces act like wires, and the gaps G act like resistors.
A relay Electromechanical relay principle Electromechanical relay schematic showing a control coil, four pairs of normally open and one pair of normally closed contacts An automotive-style miniature relay with the dust cover taken off. A relay is an electrically operated switch. It consists of a set of input terminals for a single or multiple ...
A reed relay [i] is a type of relay that uses an electromagnet to control one or more reed switches. The contacts are of magnetic material and the electromagnet acts directly on them without requiring an armature to move them.
Hall effect magnetometers (also called tesla meters or gauss meters) use a Hall probe [23] with a Hall element to measure magnetic fields or inspect materials (such as tubing or pipelines) using the principles of magnetic flux leakage. A Hall probe is a device that uses a calibrated Hall effect sensor to directly measure the strength of a ...
Multiple versions of self-exitation exist: [1] a shunt, the simplest design, uses the main winding for the excitation power; an excitation boost system (EBS) is a shunt design with a separate small generator added to temporarily provide an energy boost when the main coil voltage drops (for example, due to a fault). The boost generator is not ...
To operate the coil continually, the DC supply current must be repeatedly connected and disconnected to create the magnetic field changes needed for induction. [1] To do that, induction coils use a magnetically activated vibrating arm called an interrupter or break (A) to rapidly connect and break the current flowing into the primary coil. [1]