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Topic: Leakage inductance

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	Leakage inductance - Wikipedia, the free encyclopedia
		Leakage inductance is that property of an electrical transformer that causes a winding to appear to have some self-inductance in series with the mutually-coupled transformer windings.
		Leakage inductance is primarily caused by the design of the core and the windings.
		Leakage reactance is also used for some negative resistance devices, such as neon signs, where a transformer action is required as well as current limiting.
	en.wikipedia.org /wiki/Leakage_inductance (406 words)

	Transformer page 2
		The standard transformer had leakage inductance ~.5 mh and the bifilar was ~.16 mh.
		The primary inductance was slightly higher for the bifilar transformer (~5-10%) and the secondary inductance was unchanged.
		The leakage inductance is effectively in series with the primary so the main concern is its value at 20k.
	home.comcast.net /~hendentures/index_files/Page430.htm (1061 words)

	Proper Layout and Component Selection Controls EMI - Maxim/Dallas
		Thus, the leakage inductance results from magnetic fields in the air (because fields in the core couple both the primary and secondary windings).
		Leakage inductance is caused by a magnetic field that links one winding but not the other.
		Another problem with leakage inductance is the large voltage generated when the current changes quickly, as it does in the transformer of most switching power supplies.
	www.maxim-ic.com /appnotes.cfm?an_pk=716 (5724 words)

	Two-wire electronic dimming ballast for gaseous discharge lamps - Patent 4392087 (Site not responding. Last check: 2007-10-06)
		According to the present invention, a tuning capacitor is located in the secondary and the transformer of the ballast is constructed in a manner which harnesses the natural leakage inductance in the secondary such that both the inductance and capacitance normally on the primary side are on the secondary side.
		The secondary leakage inductance in conjunction with the tuning capacitor provide tuned sine wave output to the fluorescent lamps at the operating frequency of the inverter throughout the dimming range of the tubes.
		The technique contemplates eliminating the necessity of using additional expensive inductance components in the ballast system such as the choke coil by taking advantage of the natural leakage inductance of a modified transformer which is substituted for and functions in the same manner as the external inductance of the choke coil.
	www.freepatentsonline.com /4392087.html (5954 words)

	Ignition Coil — Tech — Terms & Definitions - Hot Rod Magazine (Site not responding. Last check: 2007-10-06)
		The property of a coil that allows voltage to be induced is called inductance, and inductance is the principle upon which hundreds of millions of ignition systems have been built over the years.
		Inductance is measured in a unit called the "Henry." Most automotive ignition coils, from purely stock to full-on racing units, are rated at between 4 and 10 thousandths of a Henry, called 4 to 10 milliHenrys (abbreviated 4mH).
		Thus, as you change the shape of the spark in the combustion chamber by altering the leakage inductance of your coil, you are also introducing a change in the ignition timing itself.
	www.hotrod.com /techarticles/ignition_coil_tech (4296 words)

	Power Transformer Attenuates Harmonics
		Leakage inductance between the primary and secondary windings in all transformers already functions as a first-order low-pass filter.
		Previously, leakage inductance and interwinding capacitance were viewed as a byproduct of the design of line-frequency transformers, a function of spacings and dielectrictics.
		The combination of the leakage inductance with the transformed capacitance from secondary to primary (C) and the primary dc-resistance (R) acts as a second-order low-pass filter.
	powerelectronics.com /mag/power_power_transformer_attenuates (3052 words)

	diyAudio Forums - toroid for car amp smps
		Leakage inductance using a toroid can be an issue depending on the core shape and number of winding turns.
		Leakage inductance with ferrite toroid transformers is about the same obtained with EI or EE standard cores, provided the same core materials and sandwitching winding techniques are used, but it's almost imposible to get perfect sandwitching in a toroidal core so coupling tends to be worse
		Lowest leakage inductance is obtained when all winding are as close to the core, and as close to each other as possible.
	www.diyaudio.com /forums/showthread.php?postid=348301 (1514 words)

	the Otherpower.com Discussion Board \|\| About Inductance (Site not responding. Last check: 2007-10-06)
		Since the leakage inductance is miniscule compared to the mutual inductance (and the primary resistance will typically also be low compared to the inductive reactance of the combination), this is close to the input voltage.
		The secondary leakage inductance and secondary resistance are unchanged.
		The point, though, is that the "leakage reactances" in series with the output current in the model are small compared to the secondary resistance (and to the mutual inductance and thus the measured coil iductance).
	www.fieldlines.com /story/2006/7/4/425/44513 (4217 words)

	Leakage inductances computation (via CobWeb/3.1 planetlab1.isi.jhu.edu) (Site not responding. Last check: 2007-10-06)
		This procedure for leakage inductance reduction is the one generally used in audio transformers for expanding band pass to the high frequencies.
		It is still possible to decrease leakage inductance by decreasing number of turns in windings, which is possible with higher permeability cores.
		When designing push-pull output transformer, care must be taken of the leakage inductance between the two half-primaries (it can be obviously computed the same way as primary-secundary leakage).
	www.recherche.enac.fr.cob-web.org:8888 /~puechmor/e_transfo/node6.html (491 words)

	O'Grady Engineering - Power Supply Design Tips (via CobWeb/3.1 planetlab1.isi.jhu.edu) (Site not responding. Last check: 2007-10-06)
		Leakage inductance between the primary and secondary windings of the transformer is a real problem in switchmode power supplies.
		The spike voltage is dependent on the value of the parasitic circuit capacitance's, and the value of the leakage inductance of the transformer.
		If the leakage inductance values are large, the amplitude of the spike will be high, and could exceed the voltage withstand capabilities of the switch.
	www.ogradyeng.com.cob-web.org:8888 /designtips.html (464 words)

	Electric power engineering - Toroidal transformer leakage inductance
		You can calulate the leakage inductance of a toroidal transformer with primary and secondary wound in two layers (and not on separate sectors of the core) using the same equations as for EI-cores when you substitue the length of the leg by the mean circumference of your toroidal core.
		Because of this basic difference in design, the leakage inductance for an EI design transformer is normally many times greater than a toroidal design of the same VA rating.
		The leakage inductance is a function of the primary and secondary winding proximity, mag length, core geometry & Bmax etc. and I just can't seem to find any references to toroidal geometry in works on the subject.
	www.eng-tips.com /viewthread.cfm?qid=62576 (1336 words)

	Device for determining the parameter values for stator resistance, principal inductance and leakage inductance of an ... (Site not responding. Last check: 2007-10-06)
		The invention relates to an apparatus for determining the actual value of at least one of the stator resistance, the main inductance and the stray inductance parameters of an asynchronous machine having associated operating stator current and stator voltage vectors, from preset values of said parameters.
		for the stator resistance r.sup.s and the stray inductance x.sup..sigma.
		10 the adjustment of the stray inductance x.sup..sigma.
	www.freepatentsonline.com /4423367.html (9629 words)

	electronic - CREA semiconductor test equipments (via CobWeb/3.1 planetlab1.isi.jhu.edu) (Site not responding. Last check: 2007-10-06)
		Leakage inductance is a critical parameter for transformers, generators, and motors.
		Leakage inductance is the difference between the self-inductance and the mutual inductance of the primary and secondary windings.
		The leakage inductance contributes to a turn-off voltage spike seen by the switching device.
	www.crea-test.com.cob-web.org:8888 /electronic.htm (1340 words)

	OTimpedance
		The leakage inductance is proportional to the square of the number of turns, so you must decrease the number of turns to reduce the leakage inductance, but this is at odds with the need to increase the number of turns for good low frequency response.
		In addition to high frequency response rolloff, the transient response of a transformer is affected by the leakage inductance.
		In general, there is a minimum necessary primary inductance for a guitar amplifier to achieve the necessary frequency response to reproduce the lowest note on the guitar.
	www.aikenamps.com /OutputTransformers.html (913 words)

	Cramer Magnetics - Reference - Tolerance versus Cost
		Leakage Inductance: The coil's physical geometry and the number of turns determine leakage inductance.
		Capacitance: A coil's physical geometry and the dielectric between windings (similar to leakage inductance) determine capacity.
		Full-Load Voltage: After a design is completed, variations in output voltages are caused by turns ratio, winding resistance and leakage inductance.
	www.cramerco.com /reference-tolerance_v_cost.htm (646 words)

	Transformer leakage inductance control
		I measured a primary inductance Lp of 10 mH and a leakage inductance Ll of 1 mH.
		In my understanding, by mounting primary and secondary on two separate legs there is already an intrinsic leakage inductance that can't be reduced without winding both winding on the same bobbin.
		The interesting point of this story comes now: as the leakage inductance is directly related to the primary turn number (i.e.
	www.pupman.com /listarchives/1999/May/msg00486.html (541 words)

	Snubber Circuits Suppress Voltage Transient Spikes in Multiple Output DC-DC Flyback Converter Power Supplies - ...
		Since the leakage inductance does not find a path for the current built up in it during the switch on-time, it leads to a voltage spike at the turn-off of the MOSFET and also delays the transfer of power from the primary to the secondary.
		The main application of a RC snubber is to damp parasitic ringing in the circuit due to unclamped inductance in configurations such as the flyback converter.
		The series inductance of a large capacitance is capable of resonating with a small capacitance in parallel with it and the resulting resonant circuit will have a high Q. The resistors used should have very low inductance to avoid excessive overshoots and ringing.
	www.maxim-ic.com /appnotes.cfm/appnote_number/848 (2276 words)

	Power Supply Design: Measuring Leakage Inductance
		My off-the-top-of-my-head answer is to short the secondaries, measure the primary reactance at the switching frequency, and calculate inductance from the reactance and frequency.
		Placing the phrase "leakage inductance" in the search box on my home page yielded a discussion on how do you design snubber circuits, a related topic, and a reference to Kiltie's book.
		Several predictions of the model important for practical designs are experimentally confirmed: the leakage inductance of one winding of a three-winding transformer is increased by closer coupling between the other two windings; the leakage inductances are essentially independent of air gap, although the coupling coefficient decreases with increasing air gap length.
	www.smpstech.com /mtblog/measuring_leakage_inductance.html (543 words)

	The Tube CAD Journal: High frequency anomalies in output transformer tests
		The actual situation in a transformer is more complex than shown here, since the leakage inductance and stray capacitance is distributed throughout the windings.
		High frequency measurements are much less affected by signal level and DC current (especially since the leakage flux, which causes leakage inductance, is mostly outside of the iron core), and so these tests are pretty accurate with the fig.
		Transformer designers reduce the leakage inductance by interleaving the primary and secondary, but this tends to increase the primary-secondary capacitance.
	www.tubecad.com /october2000/page2.html (427 words)

	diyAudio Forums Archive - Designing transformer leakage inductance (via CobWeb/3.1 planetlab1.isi.jhu.edu) (Site not responding. Last check: 2007-10-06)
		The resonant tank is formed by the leakage inductance (primary and secondary tranformed to primary) and capacitor.
		I can increase leakage inductance by simply adding more space between primary and secondary, but I have no idea what a doubling of the distance does to the magnetizing inductance, and how to calculate it's magnitude.
		It seems that Magnetics Designer is capable of calculating leakage inductance since it shows up in the SPICE file he sent me. I have no idea what else he used for input.
	www.diyaudio.com.cob-web.org:8888 /forums/showthread/t-71961.html (742 words)

	White Paper On Cabling For ESL Loudspeakers by Roger Sanders Of InnerSound, Inc.
		This inductance interacts with the capacitance of an ESL to form an L/C (inductance/capacitance) resonant circuit.
		Designing and building very low leakage inductance transformers that will operate over a wide frequency range and at high voltages is extremely difficult.
		Because the conductors need to be close together for low inductance, but wide apart for low capacitance, simultaneously obtaining low inductance and low capacitance seems impossible.
	www.enjoythemusic.com /magazine/manufacture/0702/cables.htm (2783 words)

	Pulse Transformers
		The circuit treats parasitic elements, leakage inductances and winding capacitance, as lumped circuit elements, but they are actually distributed elements.
		Examples of such limits are the secondary load and winding resistances limiting the secondary current or the source impedance and primary winding resistance and primary leakage inductance limiting the primary current.
		The primary leakage inductance, Lkp, restricts the flow of primary current by opposing the source voltage.
	www.butlerwinding.com /elelectronic-transformer/pulse_transformer (2565 words)

	Audio Talk! - measureing inductance
		The leakage inductance between P&S windings is relative to
		inductance is about quadrupled, as well as the leakage inductance.
		Because of the BH curve of iron, the inductance varies with current.
	www.allaudio.org /detail-7204953.html (1516 words)

	Power Integrations - Power Puzzler 3
		LLK – primary leakage inductance – the voltage spike caused by this leakage inductance is limited by the clamp network (D1, C1 and R1)
		Results are shown for two transformers, one with higher inductance (operating in deeply continuous conduction mode) and the second with lower inductance (operating in discontinuous conduction mode).
		This is due to the different in voltage drop on the respective secondary leakage inductances.
	www.powerint.com /powerpuzzler050718/index.html (1088 words)

	Inductance - Wikipedia, the free encyclopedia
		As we see here, the geometry and material properties (if material properties are same in surface S and the material is linear) of the current loop can be expressed with single scalar quantity L.
		When two tuned circuits are loosely coupled through mutual inductance, the bandwidth will be narrow.
		When the mutual inductance is increased beyond a critical point, the peak in the response curve begins to drop, and the center frequency will be attenuated more strongly than its direct sidebands.
	en.wikipedia.org /wiki/Inductance (1460 words)

	EDN Access -- 02.16.95 LIER circuit helps power-supply efficiency
		The flyback inductor's required primary inductance, for example, can become so low that its accompanying leakage inductance becomes a significant fraction of the total inductance.
		The energy stored in the primary leakage inductance lowers the circuit's efficiency and increases the power-rating requirements for the primary-winding switching device.
		equals the leakage inductance's energy plus the energy associated with the average current sourced by the primary flyback pulse (as the current flowing in the leakage inductance returns to zero).
	www.edn.com /archives/1995/021695/04di5.htm (408 words)

	Transformers (Site not responding. Last check: 2007-10-06)
		I called Lm the mutual inductance and tha's probably not the best term, though I think that in a 1:1 the mutual inductance is about the same as the self inductance or shunt inductance or magnetizing inductance or what ever it is best called.
		Should you desire to group the series resistances Rx and the leakage inductances Lx, all on one side, just move the values from the other side, translated by the square of the turns ratio.
		Using too high inductance would not generally have much problems, but generally it is not good idea because many practical reasons (longer primary coil, more resistance, more capacitance, propably for those reasons poorer high frequency response etc.).
	www.epanorama.net /documents/components/transformers.html (4670 words)

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