"It is essentially a transformer where charge to be heated forms a single turn short circuit secondary and is magnetically coupled to the primary by an iron core. Induction heating Induction heating is the process of heating an electrically conducting object (usually a metal) by electromagnetic induction, through heat generated in the object by eddy currents. An induction heater consists of an electromagnet, and an electronic oscillator that passes a high-frequency alternating current (AC) through the electromagnet. The rapidly alternating magnetic field penetrates the object, generating electric currents inside the conductor called eddy currents. The eddy currents flowing through the"
"other and the inductance is very small. This type has the advantage that it is continuously variable over a wide range. It is used in antenna tuners and matching circuits to match low frequency transmitters to their antennas. Another method to control the inductance without any moving parts requires an additional DC current bias winding which controls the permeability of an easily saturable core material. See Magnetic amplifier. A choke is an inductor designed specifically for blocking high-frequency alternating current (AC) in an electrical circuit, while allowing DC or low-frequency signals to pass. It usually consists of a coil of"
"Inductor An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a coil around a core. When the current flowing through an inductor changes, the time-varying magnetic field induces an electromotive force (""e.m.f."") (voltage) in the conductor, described by Faraday's law of induction. According to Lenz's law, the induced voltage has a polarity (direction) which opposes the change in current that created it. As a result, inductors oppose any changes in current"
"Choke (electronics) In electronics, a choke coil is an inductor used to block higher-frequency while passing lower-frequency of direct current (DC) or alternating current (AC) in an electrical circuit, A choke usually consists of a coil of insulated wire often wound on a magnetic core, although some consist of a doughnut-shaped ""bead"" of ferrite material strung on a wire. The choke's impedance increases with frequency. Its low electrical resistance passes both AC and DC with little power loss, but its reactance limits the amount of AC passed. The name comes from blocking—""choking""—high frequencies while passing low frequencies. It is a"
"induced voltages to change. The coils are connected so that the output voltage is the difference (hence ""differential"") between the top secondary voltage and the bottom secondary voltage. When the core is in its central position, equidistant between the two secondaries, equal voltages are induced in the two secondary coils, but the two signals cancel, so the output voltage is theoretically zero. In practice minor variations in the way in which the primary is coupled to each secondary means that a small voltage is output when the core is central. This small residual voltage is due to phase shift and"
"differing phases. Later alternators were designed for varying alternating-current frequencies between sixteen and about one hundred hertz, for use with arc lighting, incandescent lighting and electric motors. As the requirements for larger scale power generation increased, a new limitation rose: the magnetic fields available from permanent magnets. Diverting a small amount of the power generated by the generator to an electromagnetic field coil allowed the generator to produce substantially more power. This concept was dubbed self-excitation. The field coils are connected in series or parallel with the armature winding. When the generator first starts to turn, the small amount of"
"a coil of wire (also called a solenoid) is constant inside the coil and zero outside the coil. This property is useful in circuits to store energy within a magnetic field. Inductors resist change in currents, therefore it will produce a current opposing the change. This is also known as Lenz's law. Because of this property, inductors oppose alternating current. Circuits are connections of electrical components. Common components are as follows: Current is defined as the change of charge per unit time, often represented as formula_8and in units of amperes (A). Voltage is the difference in electric potential between two"
"circuit can be adjusted to different frequencies by varying the inductance (L), the capacitance (C), or both. In the lowest-cost sets, the inductor was made variable via a spring contact pressing against the windings that could slide along the coil, thereby introducing a larger or smaller number of turns of the coil into the circuit. Thus the inductance could be varied, ""tuning"" the circuit to the frequencies of different radio stations. Alternatively, a variable capacitor is used to tune the circuit. Some modern crystal sets use a ferrite core tuning coil, in which a ferrite magnetic core is moved into"
"also depends on the shape of the coil, separation of the turns, and many other factors. By adding a ""magnetic core"" made of a ferromagnetic material like iron inside the coil, the magnetizing field from the coil will induce magnetization in the material, increasing the magnetic flux. The high permeability of a ferromagnetic core can increase the inductance of a coil by a factor of several thousand over what it would be without it. Any change in the current through an inductor creates a changing flux, inducing a voltage across the inductor. By Faraday's law of induction, the voltage induced"
"turns of thin wire. An iron armature and make-and-break mechanism repeatedly interrupts the current to the primary coil, producing a high-voltage, rapidly alternating current in the secondary circuit. Callan invented the induction coil because he needed to generate a higher level of electricity than currently available. He took a bar of soft iron, about long, and wrapped it around with two lengths of copper wire, each about long. Callan connected the beginning of the first coil to the beginning of the second. Finally, he connected a battery, much smaller than the enormous contrivance just described, to the beginning and end"
"feed the output of the interrupter to an induction coil in order to increase the voltage applied to the patient by transformer action. In Pulvermacher's patent however, there is no mention of using induction coils - the Pulvermacher battery could produce large voltages merely by adding more links to the chain. However, the interrupter still had an effect in that an interrupted current produces a stronger sensation of electric shock in the patient than a steady current. A novel feature of Pulvermacher's interrupter was that it was operated by the action of a vibrating spring kept in motion by the"
"magnetic core, which can be slid or screwed in or out of the coil. Moving the core farther into the coil increases the permeability, increasing the magnetic field and the inductance. Many inductors used in radio applications (usually less than 100 MHz) use adjustable cores in order to tune such inductors to their desired value, since manufacturing processes have certain tolerances (inaccuracy). Sometimes such cores for frequencies above 100 MHz are made from highly conductive non-magnetic material such as aluminum. They decrease the inductance because the magnetic field must bypass them. Air core inductors can use sliding contacts or multiple"
"three solenoidal coils placed end-to-end around a tube. The center coil is the primary, and the two outer coils are the top and bottom secondaries. A cylindrical ferromagnetic core, attached to the object whose position is to be measured, slides along the axis of the tube. An alternating current drives the primary and causes a voltage to be induced in each secondary proportional to the length of the core linking to the secondary. The frequency is usually in the range 1 to 10 kHz. As the core moves, the primary's linkage to the two secondary coils changes and causes the"
"Induction generator An induction generator or ""asynchronous generator"" is a type of alternating current (AC) electrical generator that uses the principles of induction motors to produce power. Induction generators operate by mechanically turning their rotors faster than synchronous speed. A regular AC induction motor usually can be used as a generator, without any internal modifications. Induction generators are useful in applications such as mini hydro power plants, wind turbines, or in reducing high-pressure gas streams to lower pressure, because they can recover energy with relatively simple controls. An induction generator usually draws its excitation power from an electrical grid. Because"
"Interrupter An interrupter in electrical engineering is a device used to interrupt the flow of a steady direct current for the purpose of converting a steady current into a changing one. Frequently, the interrupter is used in conjunction with an inductor (coil of wire) to produce increased voltages either by a back emf effect or through transformer action. The largest industrial use of the interrupter was in the induction coil, the first transformer, which was used to produce high voltage pulses in scientific experiments and to power arc lamps, spark gap radio transmitters, and the first X-ray tubes, around the"
"currents (due to the airgap) and limited in voltage to less than 20kV. An induction regulator for power networks is usually designed to have a nominal voltage of 14kV and ±(10-15)% of regulation, but this use has declined. Nowadays, its main uses are in electrical laboratories and arc welding. Induction regulator An induction regulator is an alternating current electrical machine, somewhat similar to an induction motor, which can provide a continuously variable output voltage. The induction regulator was an early device used to control the voltage of electric networks. Since the 1930s it has been replaced in distribution network applications"
"conjunction with a variable-position coil to vary the voltage in the line by varying the alignment of the two coils. Rotated 90 degrees apart, the secondary coil is affected by two equal but opposite fields from the primary, which effectively cancel each other out and produce no voltage in the secondary. These coils resembled the standard rotor and stator as used in an electric motor, except that the rotor was held against rotation using brakes and was moved to specific positions using high-torque gearing. Because the rotor did not ever turn a complete revolution, a commutator was not required and"
"Loading coil A loading coil or load coil is an inductor that is inserted into an electronic circuit to increase its inductance. The term originated in the 19th century for inductors used to prevent signal distortion in long-distance telegraph transmission cables. The term is also used for inductors in radio antennas, or between the antenna and its feedline, to make an electrically short antenna resonant at its operating frequency. The concept of loading coils was discovered by Oliver Heaviside in studying the problem of slow signalling speed of the first transatlantic telegraph cable in the 1860s. He concluded additional inductance"
"uses the principle of a fixed-position field coil and a second field coil that can be rotated on an axis in parallel with the fixed coil, similar to a variocoupler. When the movable coil is positioned perpendicular to the fixed coil, the magnetic forces acting on the movable coil balance each other out and voltage output is unchanged. Rotating the coil in one direction or the other away from the center position will increase or decrease voltage in the secondary movable coil. This type of regulator can be automated via a servo control mechanism to advance the movable coil position"
"Rogowski coil A Rogowski coil, named after Walter Rogowski, is an electrical device for measuring alternating current (AC) or high-speed current pulses. It consists of a helical coil of wire with the lead from one end returning through the centre of the coil to the other end, so that both terminals are at the same end of the coil. The whole assembly is then wrapped around the straight conductor whose current is to be measured. There is no metal (iron) core. The winding density, the diameter of the coil and the rigidity of the winding are critical for preserving immunity"
"across it, the primary winding and the capacitor form a tuned circuit, and as the stored energy oscillates between the inductor formed by the coil and the capacitor, the changing magnetic field in the core of the coil induces a much larger voltage in the secondary of the coil. More modern electronic ignition systems operate on exactly the same principle, but some rely on charging the capacitor to around 400 volts rather than charging the inductance of the coil. The timing of the opening of the contacts (or switching of the transistor) must be matched to the position of the"
"internal working of this meter. Voltage drop across an inductor is directly proportion to frequency of the source voltage, as we increase the frequency of the applied voltage the voltage drop across the inductor L1 increase that means the voltage impressed between the coil 1 is increased hence the current through the coil 1 increase while the current through the coil 2 decreases. Since the current through the coil 1 increases the magnetic field also increases and the magnetic needle attracts more towards the left side showing the increment in the frequency. Similar action will takes if decrease the frequency"
"500 kW. Induction heaters within these ranges are used on medium to larger components and applications such as the induction forging of a shaft. ""Mains"" (or ""supply"") ""frequency"" induction coils are driven directly from the standard AC supply. Most mains-frequency induction coils are designed for single phase operation, and are low-current devices intended for localised heating, or low-temperature surface area heating, such as in a drum heater. The basic principle involved in induction heating was discovered by Michael Faraday as early as 1831. Faraday's work involved the use of a switched DC supply provided by a battery and two windings"
"transformers are widely used in radio circuits as bandpass filters, and in switching power supplies. In 1894 Nikola Tesla used resonant inductive coupling, also known as ""electro-dynamic induction"" to wirelessly light up phosphorescent and incandescent lamps at the 35 South Fifth Avenue laboratory, and later at the 46 E. Houston Street laboratory in New York City. In 1897 he patented a device called the high-voltage, resonant transformer or ""Tesla coil."" Transferring electrical energy from the primary coil to the secondary coil by resonant induction, a Tesla coil is capable of producing very high voltages at high frequency. The improved design"
"It also prevents low direct current voltages from passing. Repeating coil In telecommunications, a repeating coil is a voice-frequency transformer characterized by a closed magnetic core, a pair of identical balanced primary (line) windings, a pair of identical but not necessarily balanced secondary (drop) windings, and low transmission loss at voice frequencies. It permits transfer of voice currents from one winding to another by magnetic induction, matches line and drop impedances, and prevents direct conduction between the line and the drop. It is a special application of an isolation transformer, and is often used to prevent ground loops or earth"
"the receiver. The induced alternating current may either drive the load directly, or be rectified to direct current (DC) by a rectifier in the receiver, which drives the load. A few systems, such as electric toothbrush charging stands, work at 50/60 Hz so AC mains current is applied directly to the transmitter coil, but in most systems an electronic oscillator generates a higher frequency AC current which drives the coil, because transmission efficiency improves with frequency. Inductive coupling is the oldest and most widely used wireless power technology, and virtually the only one so far which is used in commercial"
"operate with power conversion in either direction. Power conversion from AC to DC is called ""rectification"" and conversion from DC to AC is called ""inversion"". The direct current equipment often includes a coil (called a ""reactor"") that adds inductance in series with the DC line to help smooth the direct current. The inductance typically amounts to between 0.1 H and 1 H. The smoothing reactor can have either an air-core or an iron-core. Iron-core coils look like oil-filled high voltage transformers. Air-core smoothing coils resemble, but are considerably larger than, carrier frequency choke coils in high voltage transmission lines and"
"meter is the electromechanical watt-hour meter. On a single-phase AC supply, the electromechanical induction meter operates through electromagnetic induction by counting the revolutions of a non-magnetic, but electrically conductive, metal disc which is made to rotate at a speed proportional to the power passing through the meter. The number of revolutions is thus proportional to the energy usage. The voltage coil consumes a small and relatively constant amount of power, typically around 2 watts which is not registered on the meter. The current coil similarly consumes a small amount of power in proportion to the square of the current flowing"
"Repeating coil In telecommunications, a repeating coil is a voice-frequency transformer characterized by a closed magnetic core, a pair of identical balanced primary (line) windings, a pair of identical but not necessarily balanced secondary (drop) windings, and low transmission loss at voice frequencies. It permits transfer of voice currents from one winding to another by magnetic induction, matches line and drop impedances, and prevents direct conduction between the line and the drop. It is a special application of an isolation transformer, and is often used to prevent ground loops or earth loops, which cause humming or buzzing in audio circuits."
"due to Ampere's circuital law. Coils are widely used in electronic components such as electromagnets, inductors, transformers, electric motors and generators. A coil without a magnetic core is called an ""air core"" coil. Adding a piece of ferromagnetic or ferrimagnetic material in the center of the coil can increase the magnetic field by hundreds or thousands of times; this is called a magnetic core. The field of the wire penetrates the core material, magnetizing it, so that the strong magnetic field of the core adds to the field created by the wire. The amount that the magnetic field is increased"
"or circuit powered by the stored energy in the inductor. This circuit supplies a current to the inductor to replace the current from the battery, so the inductor current does not drop abruptly, and it does not develop a high voltage. The voltage across the inductor is limited to the forward voltage of the diode, around 0.7 - 1.5V. This ""freewheeling"" or ""flyback"" current through the diode and inductor decreases slowly to zero as the magnetic energy in the inductor is dissipated as heat in the series resistance of the windings. This may take a few milliseconds in a small"
"bulbs that would glow in an oscillating electric field from a high voltage, high frequency power source. For a high frequency source Tesla powered a Ruhmkorff coil (induction coil) with his high frequency alternator. He found that the core losses due to the high frequency current overheated the iron core in the Ruhmkorff coil and melted the insulation between the primary and secondary windings. To fix this problem Tesla changed the design so that there was an air gap instead of insulating material between the windings, and made the iron core adjustable so it could be moved in or out"
"blocks it. The inductor is a conductor, usually a coil of wire, that stores energy in a magnetic field in response to the current through it. When the current changes, the magnetic field does too, inducing a voltage between the ends of the conductor. The induced voltage is proportional to the time rate of change of the current. The constant of proportionality is termed the inductance. The unit of inductance is the henry, named after Joseph Henry, a contemporary of Faraday. One henry is the inductance that will induce a potential difference of one volt if the current through it"