Inductive voltage spikes
An electromagnet is a large inductor Inductance (measured in henries) is an effect resulting from the magnetic field that forms around a current-carrying conductor that tends to resist changes in the current. Electric current through the conductor creates a magnetic flux proportional to the current. A change in this current creates a change in magnetic flux that, in turn, by Faraday', and resists changes in the current through it's windings. Any sudden changes in the winding current cause large voltage spikes across the windings. This is because when the magnet is turned on energy from the circuit must be stored in the magnetic field, and when it is turned off the energy in the field is returned to the circuit.
If an ordinary switch In electronics, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another. The most familiar form of switch is a manually operated electromechanical device with one or more sets of electrical contacts. Each set of contacts can be in one of two states: either ' is used to control the winding current, this can cause sparks at the terminals of the switch. This doesn't occur when the magnet is switched on, because the voltage is limited to the power supply voltage. But when it is switched off, the energy in the magnetic field is suddenly returned to the circuit, causing a large voltage spike and an arc An electric arc is an electrical breakdown of a gas which produces an ongoing plasma discharge, resulting from a current flowing through normally nonconductive media such as air. A synonym is arc discharge. The phenomenon was first described by Vasily V. Petrov, a Russian scientist who discovered it in 1802. An archaic term is voltaic arc as used across the switch contacts, which can damage them. With small electromagnets a capacitor A capacitor or condenser is a passive electronic component consisting of a pair of conductors separated by a dielectric. When a voltage potential difference exists between the conductors, an electric field is present in the dielectric. This field stores energy and produces a mechanical force between the plates. The effect is greatest between wide, is often used across the contacts, which reduces arcing by temporarily storing the current, allowing the current through the electromagnet to change more slowly. Large electromagnets are usually powered by variable current electronic power supplies Power supply is a reference to a source of electrical power. A device or system that supplies electrical or other types of energy to an output load or group of loads is called a power supply unit or PSU. The term is most commonly applied to electrical energy supplies, less often to mechanical ones, and rarely to others, controlled by a microprocessor A microprocessor incorporates most or all of the functions of a central processing unit on a single integrated circuit (IC). The first microprocessors emerged in the early 1970s and were used for electronic calculators, using binary-coded decimal (BCD) arithmetic on 4-bit words. Other embedded uses of 4- and 8-bit microprocessors, such as, which prevent voltage spikes by accomplishing current changes in gentle ramps. It may take several minutes to energize or deenergize a large magnet.
<<Table of Contents An electromagnet is a type of magnet in which the magnetic field is produced by the flow of electric current. The magnetic field disappears when the current ceases | Next>> | Show All>>
