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Topic: Zigzag transformer

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	Transformer Encyclopedia Articles @ Lighted.org (Site not responding. Last check: 2007-11-03)
		Hence in an ideal transformer, the ratio of the primary and secondary voltages is equal to the ratio of the number of turns in their windings, or alternatively, the voltage per turn is the same for both windings.
		Toroidal transformers are built around a ring-shaped core, which is made from a long strip of silicon steel or permalloy wound into a coil, from powdered iron, or ferrite, depending on operating frequency.
		Oil-filled transformers undergo prolonged drying processes, using vapor-phase heat transfer, electrical self-heating, the application of a vacuum, or combinations of these, to ensure that the transformer is completely free of water vapor before the cooling oil is introduced.
	www.lighted.org /encyclopedia/Transformer (4788 words)

	Zigzag transformer - Wikipedia, the free encyclopedia
		A zigzag transformer is a special purpose transformer.
		Consider a three-phaseY (wye) transformer with an earth connection on the neutral point.
		When a zigzag transformer is connected to a healthy electrical system, negligible current flows in the connection between the zigzag's neutral point and earth.
	en.wikipedia.org /wiki/Zigzag_transformer (355 words)

	Hitran Corporation - Custom Transformer and Inductor Manufacturer
		Auto transformers can be single or three phase and are best used where a small percentage of voltage raising or lowering is required and isolation between two circuits is not required.
		Two transformers are connected: one with a center tap called a main and one with an 86.6% tap called a teaser.
		A zigzag transformer is used in connection with 3 phase and is made up of 6 coils connected in a "Y" manner.
	www.hitrancorp.com /faq.html (1917 words)

	FAQ LIST
		It is a transformer that insulates the primary circuit from the secondary circuit.
		A transformer in which the low voltage winding (secondary) is connected to the input or power source and the high voltage winding (primary) is connected to the output or load.
		Buck-boost transformers are conventional low voltage, single-phase distribution transformer, with standard primary voltages of 120, 240 or 480 volts, and secondary voltages of 12, 16, 24, 32 or 48 volts.
	www.hammondpowersolutions.com /i_faqlisttext.html (8857 words)

	System for reducing harmonics by harmonic current injection - Patent 5499178
		Transformer 404 is a delta-wye transformer having a delta connected primary winding 408 and wye connected secondary winding 410.
		Transformer 564 is a delta-wye transformer having a delta connected primary winding 568 and a wye connected secondary winding 570.
		Transformer 604 is a delta to wye transformer having a delta connected primary winding 608 and a wye connected secondary winding 610.
	www.freepatentsonline.com /5499178.html (11997 words)

	Mine Power Substations
		Transformers feeding power to surface loads must be installed within the Mine Power Substation ground grid if their source of power is tapped from the underground mine power transmission.
		Where the substation primary or supply voltage is equal to the mine transmission voltage, the main transformer may be omitted and a zigzag transformer used to derive a system neutral, if the neutral is not otherwise available.
		“Zigzag” or grounding transformers may be utilized on delta-connected secondaries for deriving the neutral for the four-wire transmission circuit.
	www.dep.state.pa.us /dep/deputate/minres/dms/website/approval/minepower.html (1093 words)

	MARELCO POWER SYSTEMS, Inc. (Site not responding. Last check: 2007-11-03)
		A step-down transformer is one in which the input (primary) windings exceed in number the output (secondary) windings, thus the ratio of voltage is from the high voltage winding to a low voltage winding or windings.
		Transformers are supplied with taps to adjust the transformer voltage to the correct input or output voltage or to permit selecting various voltages for various purposes, adjustments, etc. On some transformers the primary is equipped with taps to vary the primary approximately 10%.
		Other transformers have taps on the secondary and are used for such purposes as welders, furnaces and other types of loads where it is necessary to change the voltage to match the load or to supply different voltages to various sections of a complex piece of equipment like a motor drive system.
	www.marelco.com /faq.htm (9472 words)

	Zig zag - Wikipedia, the free encyclopedia
		A Zigzag transformer is an engineering device for electrical systems.
		ZigZag was the name of a UK rock music magazine.
		ZigZag (software) is a data model designed and trademarked by Ted Nelson.
	en.wikipedia.org /wiki/ZigZag (261 words)

	Basics of a transformer (Site not responding. Last check: 2007-11-03)
		The transformer may be defined as a device in which two or more stationary electric circuits are coupled magnetically, the windings linked by a common timevarying magnetic flux.
		Frequently upon energizing a power transformer, there is an inrush of exciting current which may initially be as high as eight times the rated current of the excited winding even with all other windings open.
		The losses in a transformer are the core losses, which for a given voltage and frequency are practically independent of the load; the copper losses due to the resistance of the windings; and the stray losses, largely due to eddy currents induced by the leakage fluxes in the tank and other parts of the structure.
	leeh.ee.tut.fi /transformer/tra211.htm (672 words)

	Phase Shifting - Jean-Guy Boudrias (Site not responding. Last check: 2007-11-03)
		Transformers must be derated anywhere from 80 to 50% of their nominal value if they are not built to withstand the harmonic heating.
		Normally these zigzag transformers (filters) should be installed close to the application to cancel the triplen on the neutral before they see the impedance of the line (The client originally only wanted to save his transformer, which was heating up).
		This transformer is 0º primary-secondary phase shifted and has the capacity of canceling triplen harmonics on its secondary and as we mentioned the secondary has a low zero sequence impedance (<1 per cent).
	www.currentthinking.com /pqresource/phases.htm (3403 words)

	Zigzag Phase-Shifting Transformer (SimPowerSystems)
		The Zigzag Phase-Shifting Transformer block implements a three-phase transformer with a primary winding connected in a zigzag configuration and a configurable secondary winding.
		The resistance and leakage inductance of the windings 1 of the single-phase transformers used to implement the primary winding of the Zigzag Phase-Shifting Transformer.
		The resistance and leakage inductance of the windings 2 of the single-phase transformers used to implement the primary winding of the Zigzag Phase-Shifting Transformer.
	www.weizmann.ac.il /matlab/toolbox/powersys/zigzagphaseshiftingtransformer.html (615 words)

	The Basics of Zigzag Transformers
		Due to its composition, a zigzag transformer is more effective for grounding purposes because it has less internal winding impedance going to the ground than when using a wye-type transformer.
		With the zigzag transformer, you typically insert a resistor between the neutral point and ground to limit ground fault current on the system.
		With the zigzag connection, the currents in the two halves of the windings on each leg of the transformer flow in opposite directions, avoiding saturation.
	bg.ecmweb.com /ar/electric_basics_zigzag_transformers (489 words)

	Mine Safety and Health Administration (MSHA) - Program Policy Manual - Volume V; 75.520 through 75.802
		Consequently, the kVA rating of a zigzag grounding transformer or a wye-delta grounding transformer bank shall not be less than the rated phase-to-neutral voltage of the system (VON) in kV times the rated ground-fault current of the system (I) in amperes.
		Transformer banks connected wye on the primary side and supplied power from a resistance-grounded circuit shall not have the primary neutral grounded.
		When used, grounding transformers shall be connected on the line side of circuit breakers so that the system will always be grounded and must be located in/or adjacent to the same substation as the power source transformers.
	www.msha.gov /regs/complian/ppm/PMVOL5G.HTM (2803 words)

	2793a - Transformer Turn Ratio Meter
		Transformer Turns Ratio Meter type 2793a is the successor of the very successful Tettex transformer turns ratio meter type 2793.
		A product of close collaboration with transformer turns ratio users world-wide and industry specialists in current and voltage transformers allowed us to develop an instrument with unbeaten performance.
		The simple ratio of turns is not sufficient to detect all possible failures of a power transformer winding.
	www.hipotronics.com /tettex/2793/2793body1.htm (282 words)

	Ch 2_text
		Transformer K-factor is an index used to calculate the derating of standard transformers when harmonic currents are present [14].
		Sometimes, a specially designed transformer (zigzag) is used to trap triplen harmonic currents and to prevent the currents flowing back to the source from the nonlinear load.
		This zigzag transformer is usually designed to provide a low harmonic impedance between its windings compared to the source harmonic impedance.
	engr.calvin.edu /PRibeiro_WEBPAGE/IEEE/ieee_cd/chapters/CHAP_2/c2toc/c2_textf.html (4002 words)

	NEMA Surge Protection Institute - Glossary (M-Z)
		The neutral is bonded to ground on the output of a three-phase delta-wye transformer.
		For example, paralleling for capacity two transformers means that two 50-kVA units in parallel have the sum of their individual ratings, i.e., the power of a single 100-kVA transformer.
		Transformer - A device used for changing the voltage of an ac circuit and/or isolating a circuit from its power source.
	www.nemasurge.com /glossarym-z.html (5860 words)

	Image compression and expansion apparatus using a effectively modifiable quantization table - Patent 6501858 (Site not responding. Last check: 2007-11-03)
		As a result of Inverse Discrete Cosine Transform, reconstruction image data P.sub.xy for every 8.times.8 picture element block are obtained and then the image data P.sub.xy are outputted from the image data output terminal 12 as a component image having an 8 -bit width.
		Thus, the component image of 8.times.8 picture elements is transformed by two dimensional Discrete Cosine Transform and quantized in order to compress the component image, which greatly decreases the transmitted bits as a result.
		The Discrete Cosine Transform coefficients S.sub.uv are transformed into a zigzag order, then divided by values Q.sub.uv, which are stored in the quantization table 4, at the quantizer 3.
	www.freepatentsonline.com /6501858.html (3160 words)

	Electric power engineering - Zig-zag transformer winding
		The zig zag arrangement is done so as to reduce the cross section size of the core of the transformer, because the fault current is split between 2 limbs of the transformer, reducing the flux when a fault occurs.
		On a quad output transformer one winding wil be zig-zag (zero degrees), the next one wye (30 degrees) and the other two forked wye giving 15 and 45 degrees of phase shift.
		Also, back in the days of mercury arc and hydrogen arc rectifiers the transformer feeding the rectifiers would have zig-zag windings so that the direct current would inherently cancel and the transformer would be more tolerant of uneven distribution of the DC between 3 pulse groups.
	www.eng-tips.com /viewthread.cfm?qid=104607 (1405 words)

	Electric power engineering - zigzag transformer?
		(Thus, a zigzag transformer is connected on the delta side of a transformer) Sometimes a combined auxiliary and zigzag transformer are used, the zigzag transformer for a grounding point, and the auxiliary transformer as the substation supply.
		A zigzag transformer is also called an interconnected-star earthing transformer or a Neutral-earthing coupler (NEC) In South Africa there is still a lot in use and they are easily obtainable.
		There the 132/33kV transformers are Yd connected with auxliaray / zigzag transformers providing the neutral point for 33kV system and also power supplies for the substation (precisely the way you explained).
	www.eng-tips.com /viewthread.cfm?qid=118652&page=1 (548 words)

	TransÉnergie Technologies (Site not responding. Last check: 2007-11-03)
		AC and DC filters, smoothing reactors, converter transformers and pole circuits are modelled with R, L and C passive elements.
		These models are built using combinations of single-phase transformers with one or two windings.
		The number of sections is adjusted according to the frequency range and the length of the lines to be simulated.
	www.hydroquebec.com /transenergie-tech/en/produits/modele.html (538 words)

	Glossary of Terms
		It collects gas that is gradually released from small internal problems such as bad connections, small arcs, etc. until the volume of gas operates a mercury switch which then gives an alarm signal.
		It will detect a larger flow of gas and operate a switch to give a trip signal which can be used to trip the primary device and de-energize the transformer until the severity of the fault can be determined.
		This device is often referred to as a "Buchholz Relay" which refers to the switching mechanism.
	fpptech.sasktelwebhosting.com /support/glossary/g.htm (290 words)

	Transformer Operational Principles, Selection And Troubleshooting engineering continuing education course.
		Transformers are major components of electrical power systems.
		This course combines theoretical and practical aspects of transformer design, operation, maintenance and troubleshooting.
		The course emphasizes the importance of the magnetic properties of the core design on the transformer's operational performance and electrical properties.
	www.epic-edu.com /epic/products/seminar/apr2006/96-0408-1671.htm (1021 words)

	New Topologies for Connecting Power Electronic Converters to the Utility Grid (Site not responding. Last check: 2007-11-03)
		The currents add up in the secondary winding of the transformer which is shown in the left plot of Figure 5.
		Further, a single-phase transformer is connected between ‘N’ and the dc-link mid-point ‘h’.
		On the secondary side of the single-phase transformer a single-phase boost power factor correction circuit is implemented as shown in Figuer 6.
	www.iet.auc.dk /danprof/sth/sth.html (1509 words)

	zig zag transformer input data - Topic Powered by eve community
		Wed January 19 2005 09:56 PM with regards to the inputing values for the zigzag transformer.
		Thu January 27 2005 03:25 PM I need to be really sure about this matter, because i have done a google search that points to comments made by edsa regarding the model of the zig zag transformer.
		For EDSA transformer with a winding of ZigZag, it needs input of additional grounding impedance.
	forums.edsa.com /groupee/forums/a/tpc/f/2076038832/m/6161036801/inc/1 (274 words)

	INVERTER CONTROL (Site not responding. Last check: 2007-11-03)
		While the sketch diagram of the zigzag transformer is shown in
		The method though very reliable uses the zigzag transformer, thereby adding weight to the circuit.
		Due to the presence of high magnetic circuit the speed of response to control signals is rather poor.
	www.e-shikshalaya.com /inverter_files/inver1(part9).htm (445 words)

	Earthing problem (Site not responding. Last check: 2007-11-03)
		The 11 KV of those transformers and the first genset are connected to one bus bar, which is connected also to a zigzag transformer with neutral earthed.
		In case of connecting either the Z transformer or the 400 v genset to the bus with 11 KV genset the neutral CT equal 27AMP measured on 11kv genset, and 12 AMP measured on Z transformer neutral wire, and 15 AMP measured on 400 volt transformer neutral wire.
		When you connect the genset to the Z transformer then the 3rd harmonics circulate around the transformer.
	www.control.com /1026191116/index_html (741 words)

	(WO/2000/013135) METHOD AND APPARATUS FOR IMAGE COMPRESSION (Site not responding. Last check: 2007-11-03)
		A zigzag circuit (24) is coupled to the DCT transformer.
		A Q-factor estimator (26) is coupled to DCT transformer.
		A DC coding circuit (28) is coupled to zigzag circuit and a quantization circuit (30) is coupled to zigzag and the Q-factor circuits.
	www.wipo.int /ipdl/IPDL-CIMAGES/view/pct/getbykey5?KEY=00/13135.000309 (207 words)

	Product Detail
		The characteristics of the various transformer connections and possible operating problems under normal or abnormal conditions are treated for three-phase distribution systems.
		These systems are characterized by primary voltages up to and including 34.5 kV, usually have a preponderance of connected transformers with low-voltage windings below 1000 V, and furnish electric service to consumers.
		All combinations of Delta and Y, grounded and ungrounded, T connected, zigzag, and certain special connections are considered.
	shop.ieee.org /ieeestore/Product.aspx?product_no=SS6924 (125 words)

	Pradeep Kumar Gangadharan
		The 132KV neutral is solidly earthed on the 11kV side there is a zigzag/star 11/0.38kV earthing transformer with the neutral point of the zigzag winding solidly earthed.
		The LV side CT's are in the incoming 11kV panel and the earthing transformer is located near the power transformer.
		But some of my senior colleagues here tell me that even for a fault near the transformer on the 132kV side incoming cables the neutral point CT will have current flowing through it and hence the standby e/f(HV) will act.
	publish.uwo.ca /~pgangadh/interaction.htm (527 words)

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