Pdf kozlowski stray losses and local overheating hazard in transformers
“RNM2D 0 Fast Stray Losses Hazard Evaluation on Transformer Tank Wall & Cover due to Zero Sequence”, Proc. of 3 rd Advanced Research Workshop on Transformers (ARWtr2010), Santiago de Compostela, Spain, pp. 338-343, Oct.
“Stray losses and local overheating hazard in transformers. Turowski. Kozlowski.Tech in 1990 from Indian Institute of Technology (UT).” IEEE Trans. in 1980 from Indian Institute of Technology. IEE. 1280-1287. I El Nahas.” Paper no. CIGRE 1972. R. no 5. and X Zihong. “Three dimensional computation of transformer leakage fields and associated losses:’ IEEE Trans. ” Paper no. C E R E
The problem of stray losses due to high current carrying conductors has been reported in Junyou et al. (1994) and Renyuan et al. (1996), while preventive measures against local overheating have been discussed in (Junyou et al., 1996) and (Ho et al., 2008).
A more serious effect of harmonic loads served by transformers is due to an increase in winding eddy current losses. Eddy currents are circulating currents in the conductors induced by the sweeping action of the leakage magnetic field on the conductors. Eddy current concentrations are higher at the ends of the transformer windings due to the crowding effect of the leakage magnetic fields at
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A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. A varying current in one coil of the transformer produces a varying magnetic field, which in turn induces a voltage in a second coil.
where P is the losses due to load I 2 R, P EC is the winding eddy losses and P OSL is the other stray losses. Other aspect to be take into account when estimating internal losses derived from harmonic load currents is the presence of a dc value in the load current which increase the magnetizing current and audible sound level without strongly penalizing the transformer core loss.
A K-4 reading would mean that the stray loss heating effects are four times normal. A standard transformer is, in effect, a K-1 transformer. As with THD, it is misleading to make a K-factor reading at the load or receptacle because there will be a certain amount of upstream cancellation; transformer K-factor is what counts. Once the K-factor is determined, choose the next higher trade size. K
The preferred power supply also includes a capacitor 7 connected across the secondary of the high-frequency transformer 44, the load and the shunt 5, as well as capacitors 8 connected from various points to chassis ground in order to eliminate stray high-frequency signals.
“Stray losses and local overheating hazard in transformers. Kharagpur. vol PWRD-I. Komulainen and H Nordman. eddy and circulating current problems taking magnetic saturation and effect of eddy current and circulating current paths into account. Power Apparatus and Systems.4. [45] A.” AlEE Trans . vol. and J B. IEE. ”Calculation of the losses in three-phase transformer tanks. 377 -379. no
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Common Power Quality factors affecting transformers
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The frequency response of stray lossess (FRSL) test identifies short-circuits between parallel strands and local overheating due to excessive eddy current losses.
transformer are modelled and discussed and a limiting value of DC current injection is determined which gives rise to a supply current Total Harmonic Distortion (THD of 5%).
Do not place heat generating devices such as transformers and supply blocks under the island. Heat generating devices in proximity of HTB and I/O expansion modules could result in elevated temperatures and overheating, and can result in unexpected operation of inputs and outputs.
• Local overheating due to excessive eddy current losses resulting in generation of gas, carbon and other degradation products, and in insulation deterioration • Close loops between adjacent members linked by stray flux, if accompanied with poor
The UHVAC electrical equipment, which is the base of the UHVAC project and whose performance directly affects the stability of the UHV line, is the important research content of the UHVAC technology.
Local environments can degrade or contaminate dry transformers. Sunlight and overheating can chemically break down an insulation system. Contamination, such as from particulates from nearby exhaust systems and from dust and lint producing operations, can interfere with cooling, and can form short circuit paths that cause arcing. Wind blown rain can reach components that should remain dry
The problem of stray losses due to high current carrying conductors has been reported in Junyou et al. (1994) and Renyuan et al. (1996), while preventive measures against local overheating have been discussed in (Junyou et al., 1996) and (Ho et al.,
DESCRIPTION. Transformer is a vital link in a power system which has made possible the powergenerated at low voltages (6600 to 22000 volts) to be stepped up to extra highvoltages for transmission over long distances and then transformed to low …
or loss of life due to risks from faults etc., associated with its 1500V DC traction system, high voltage reticulation system and low voltage distribution systems. At railway stations, three main types of risks may exist: 1. Risks associated with 1500V DC stray leakage or fault current. 2. Electric shock risk due to 1500V DC touch & step potential rise under fault condition, in particular with
A section of this paper is devoted to the characterization of stray losses against the transformer rating (kVA) and the stray losses over load losses against the transformer rating (kVA). The experimental data presented in this work, will be helpful for a practicing engineer in the transformer industry.
they should not be ignored because if the local additional losses are too high, it can lead to local overheating, damaging of cellulose electric insulation, and degradation of mineral oil [2]. Plain magnetic steel is used in power transformers for its low price and excellent mechanical properties.
high stray loss density values might give rise to local high temperatures, more important in terms of safety and reliability. One of these particular situations occurs when high current leads pass through steel cover plates and parallel to tank walls which are thermally hazardous elements in power transformers [1]. In the literature a large amount of papers focus their results on stray power
In this study, losses analysis at bushing regions of a transformer covers is done using finite difference method (FDM), considering that FDM being more flexible to deal with the nonlinear constitutive law and easier to be implemented than finite element (FE) and analytical methods.
The high content of current harmonics requires special attention be paid to controlling additional and stray losses in the transformer, when it comes to total losses and the risks of local overheating in the windings and metallic components exposed to stray flux …
Losses in Pad-Mounted Transformers Juan Carlos Olivares, Member, IEEE, Rafael Escarela-Perez, low-voltage side are also a cost-effective ways to reduce stray losses and local overheating. We will be studying these options in the near future. II. ELECTROMAGNETIC BACKGROUND The calculation of losses in the tank wall of a pad-mounted transformer is performed using a 3-D finite-element model
Transformers subject to a fire hazard. They present a restricted inflammability, low emission of toxic sub- stances and opaque fumes. The standard offer of Winder Power covers distribution cast resin transformers from 50kVA up to 3150kVA, insulation class up to 36kV with standard or reduced losses (IEC 60076-11). TPZ3S (Distribution transformers with standard losses). TPZ3R (Distribution
The right photo shows the depth that the overheating damage penetrated into the core. Local Overheating .Figure 13 shows the result of a suspected partially blocked oil duct on the same shell-form transformer core that was discussed in the previous example. The lamination at this duct showed signs of significant overheating since the surface was black and was rough with a granular texture. it
geometry of SSI to overcome the local overheating and stray losses and maximum magnetic field on cover plate for a 1600 kVA, 400 V three phase distribution transformer using Equations (1) and (2), respectively in the cases of 3D and 2D views which has been done in MATLAB. The required parameter given in section III and Table 1. As a result the maximum of magnetic field intensity is around
2.3 Technology for reducing eddy-current and stray load losses On the load losses of the transformer, it is possible to exactly calculate the resistance and eddy-current losses in the winding. However, the source of stray load loss cannot be determined since only the differ-ence of measured load losses and the aforementioned calculated losses are obtained as collective values. At Fuji Electric
Stray flux distribution was observed in three positions along limb and yoke. Results have shown that an appreciable amount of stray flux appears inside the core even in the central packages.
equipment failure and losses. This paper will discuss enhancements that will minimize This paper will discuss enhancements that will minimize such equipment malfunctions.
The problem of stray losses due to high current carrying conductors has been reported in [1] and [2], while preventive measures against local overheating have been discussed in [3] and [4]. The
step-down transformers can be Ydown transformers can be Y-YYY, Y-DandDD and D-Y, grounded or ungrounded at the Y side. • Under steady state conditions the 3Under steady state conditions , the 3-phase voltages Vphase voltages V an ,
Power transformer.pdf [PDF Document]
of overheating problem. The overheating results are analyzed and discussed for the case of a 290MVA 235/15.75 KV generator transformer. Keyword: stray loss, induced fields, local hot spots, leakage flux, generator transformer, INTRODUCTION Power and distribution transformers are expensive and vital components in electric power transmission and distribution systems. The statistics of failures
Another transformer problem results from core loss and copper loss. Transformers are normally rated for a 60 Hz phase current load only. Higher frequency har- monic currents cause increased core loss due to eddy currents and hysteresis, resulting in more heating than would occur at the same 60 Hz current. Transformers supplying non-linear loads should be checked periodically to verify
An air cooling system, method, apparatus and kit applied to lower transformer operating temperatures, such as governed by a tank or container of oil, allowing transformer components to run more efficiently at a lower temperature level, e.g., down from the hot level operating temperatures typical in stressed conventional devices. –
kewaunee boiler model l35150 g manual Local overheating caused by blocked oil duct inside the transformer Overheating due to oil circulating pump problems (bearing wear, impeller loose or worn) Overheating due to circulating stray currents in the core, structure, and/or tank
OF STRAY LOSSES The frequency response of stray lossess (FRSL) test identifies short-circuits between parallel strands and local overheating due to excessive eddy current losses. DYNAMIC RESISTANCE Dynamic resistance measurements (DRM) are used to check the on-load tap changer (OLTC) for poorly maintained and damaged OLTC contacts. POWER / DISSIPATION FACTOR (with …
23 Insulation Oil Treatment and its’ Necessity in Power Transformers Gerards Gavrilovs, Olegs Borscevskis Riga Technical University gerards.gavrilovs@latvenergo.lv , olegs.borscevskis@latvenergo.lv
some time lead to local overheating. Hence in large power transformer, the leakage is decisive factor in design of the transformer. For a transformer with a certain impedance ,some amount of leakage flux can be controlled and stray losses resulting out of the leakage flux can be considerably reduced, and local over heating can be controlled .decrease in stray loss will improve the efficiency
Reduction in stray losses of 85.3% on each plate is an excellent alternative to decrease the total losses in the shell-form power transformers. Structural problems and critical deformations not were found, when slotted T-beams are used to support active parts of transformer.
The losses in transformers include four different types: No load losses (core losses), which are fixed and do not change with the load Copper losses, equals to I. 2. R (all harmonics have same affect) Winding eddy current losses, linear with the square of the harmonic index – P. EC I. 2. h. 2 Stray losses (in clamps, tanks, etc.), includes various losses and in estimation is linear with the 0
Challenges in Transformer Design & Manufacturing Stray losses : • Stray losses due to linkage of high magnitude of flux with magnetic materials • Stray losses form a large part, more than 20% of total load losses • These may cause hot spots
In the large power transformers the stray-field loss and the local loss density caused in the conducting parts are considerably increased with the capacity, which probably result in the hazardous local overheating and/or cause the insulation material destroyed, consequently endanger the transformer running. In the electromagnetic design of larger power transformer, the stray-field loss must be
methods to calculate and reduce the stray losses in flitch plates, frames, and tank walls for eliminating the local overheating and efficiency decreasing [3][4].
• Transformer Overheating. In the presence of current harmonics, transformers will In the presence of current harmonics, transformers will have increased iron and copper losses or Eddy currents due to stray flux losses.
Even the local, pointwise field concentration and overheating can destroy the transformer oil and isolation, it can actuate the protection system and disconnect the object from service. The problem of prediction and reduction of losses, and possible destruction of an object by local excessive heating, caused by uncontrolled eddy currents becomes especially important both from the safety and
Abstract—In large power transformers, the presence of stray currents in the structural elements near the high current bush-ings can be considerable, and this leads to hot spots. This work presents a practical analysis of overheating in the bolts that join the tank and the cover, which are near the high current bush-ings of the transformer. Overheating results are analyzed and discussed for
Read “3D non-linear magneto-thermal behavior on transformer covers, Electric Power Systems Research” on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
1120 IEEE TRANSACTIONS ON POWER DELIVERY VOL. 19 NO. 3
Stray Losses, Screening, and Local Excessive Heating Hazard in Large Power Transformers Janusz TUROWSKI Dept. of Intelligent Information Systems, WSHE – Lodz,
The 3D magneto-thermal behavior on transformer tank covers is analyzed in detail. The calculation of stray losses in the bushing adapters is, of course, also important to guarantee the total losses. However, it is difficult to directly measure the stray losses in the bushing adapter itself and therefore verify the computed values. Meanwhile it is a fact that the surface temperature can be
Due to a low stray loss component in transformers 35-110 kV below 100 MVA faulty gas generation is typically involves overheating of current-carrier connection (dangerous case) or just penetration of gases into the main tank from OLTC compartment, whereas in large unit this
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Stray losses (in clamps, tanks, etc.), includes various losses and in estimation is linear with the 0.8 power of harmony: PSL α I2h0.8 As can be seen from the above formulas, there is a di˛erence in the losses caused by the current in each harmonic order.
Transactions on Electrical Engineering, Vol. 1 (2012), No. 3 89 Operating Damages of Bushings in Power Transformers KAPINOS Jan Silesian University of Technology, Institute of Electrical Engineering and Informatics,Division of Electrical Machines
[29] M. Kozlowski, et al., Stray losses and local overheating hazard in [6] P. Moreno, Extra low frequency magnetic fields shielding with finite width planar shields, Ph.D. dissertation, University of transformers, Cigre, 1972. Washington, 1997. [30] P.D. Agarwal, Eddy-current losses in solid and laminated iron, [7] K.V. Namjoshi, et al., Power efficiency of eddy current shielding AIEE paper
CONSIDERATIONS ON POWER TRANSFORMER CONDITION
Transformers GE Grid Solutions
The stray losses in the transformer are presented in Section 4. Section 5 presents relevant aspects of the different works analyzed, followed by conclusions in Section 6. 2. Tank Losses Due to High-current Bushings There are few studies related to a single current-carrying conductor in the presence of conducting permeable surfaces. The means of preventing local overheating in the windings and
4) Stray Load Loss: Stray load losses are defined as losses other than Stator I2R, Rotor I2R, Core and Mechanical. They are primarily attributed to They are primarily attributed to leakage reactance fluxes induced by load current.
The high losses sustained due to electrical distribution fires do not imply that the systems are unreliable. There are about 270 million people in the US, occupying about 100 million housing units, with the average housing unit having 5.4 rooms [[3] ].
3D Methodology for the Overheating Assessment on Power Transformers Structural Parts Submitted for the degree of Doctor of Philosophy International Doctor …
• Safer operation of transformers with stray flux control: • Avoids local overheating • Avoids accelerated aging of oil and gas bubble generation • Appearance of stray flux losses • Windings, tank, clamping plates, tie bars and yokes • The crucial step to loss-control • Calculation of the stray flux distribution Experience and ongoing research • Fast solution of complex problem
• Control leakage flux density and reduce stray loss • Control over heating of the high current leads by redesigning the structure and lead arrangement • Improve the operational reliability of transformers by increasing the short circuit withstand strength of the windings • Minimize the effects of DC biasing on the transformer core by analyzing currently used methods • Decreased
work related to stray losses and hot spots in transformer tanks. Section III presents the copper link method to reduce hot spots on the bolts of transformer tanks.
Common power quality factors affecting transformers
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In order to improve safety and the immunity to withstand noise, mount this instrument as far away as possible from high voltage equipment, power lines, and rotating machinery.
Keywords: Overheating hazard, high stray loss density values might give rise to local high temperatures, more important in terms of safety and reliability. One of these particular situations occurs when high current leads pass through steel cover plates and parallel to tank walls which are thermally hazardous elements in power transformers [1]. In the literature a large amount of papers
losses are caused by eddy-currents that produce stray electromagnetic flux in the windings, core, core clamps, magnetic shield and other parts of the transformer. For harmonic-rich
Stray losses in transformer clamping plate can be a considerable part of the overall stray loss in transformer. In this paper clamping plate loss distribution is shown. Methods of loss reduction
Frequency response of stray losses (FRSL) The frequency response measurement of stray losses is a tool to determine short circuits of parallel strands. The resistive part of the short circuit impedance is measured over a frequency range from 15 Hz up to 400 Hz. The resistance curves of the three phases are compared. The 15 Hz values are very similar to the DC values of the primary winding
Determination of electromagnetic properties of steel for
3D Methodology for the Overheating Assessment on Power
Eddy Current Fields and Overheating Problems due to Heavy
– 3D FEM OPTIMAL DESIGN OF TRANSFORMER COVER PLATES TO
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7. LIST OF PAPERS AND ABSTRACTS LIST OF PAPERS
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A Review of Transformer Losses tandfonline.com