Transformers come in basic k factors such as 4, 9, 20, 30, 40, and 50. Determination of transformer rating 54 a pure sinusoidal threephase power supply was supplied to a nonlinear load connected to a threephase transformer. Thus, transformers are said to be k rated when they use the k factor. Subsequently, specify the transformer to have a k factor that is equal or higher than the calculated value. Under normal circumstances the value of kfactor ranges from 150. There are many different loads such as computers, solidstate devices and motors which cause a non linear load. A k factor of 1 indicates no harmonics, while a k factor of 50 is the harshest harmonic environment. The k factor transformers could be a more optimal solution cost and weight, rather than derating for. A study of kfactor power transformer characteristics by modeling simulation article pdf available in engineering, technology and applied science. Determination of transformer rating based on total harmonic distortion under balanced conditions. K is a somewhat better choice and is priced a bit higher. They also compensate for stresses on a transformer s winding insulation which prevents insulation breakdown and premature failure. The core, which makes a path for the magnetic flux. Specialty lowvoltage dry type distribution transformers.
Basics, maintenance, and diagnostics vii contents continued page 4. The kfactor is a number calculated from the harmonic spectrum of the current in a load waveform such that, regardless of the actual spectrum, loads that require the same k factor have the same heating effect on the transformer. The kfactor transformer power quality in electrical systems. Pay attention to the amount of current rms value that is involved in large kfactor measurements.
The secondary coil, which receives energy from the primary winding and delivers it to the load. Once the k factor is determined, it is used in the design of the transformer to compensate for the additional heating effects generated by the harmonic. The strategy is to calculate the k factor for your load and then specify a transformer with a k factor of an equal or higher value. Kfactor transformers have to manage continuous thermal stresses caused from harmonics and excessive neutral currents. Onyx kfactor transformers include an expanded steel core for a k20. We make certain that our worldrenowned quality is exemplified by every product carrying our label. Measuring transformer load unbalanced using a single phase power quality analyzer. Periodic capture waveforms are preferred for kfactor calculation. If the current is low compared to the 60 hz transformer rating, the k factor may not be an issue. The word demand itself says the meaning of demand factor. The excessive leakage fluxes produced during short circuit and over loads, develops severe. Krated transformer manufacturers mumbai india neelkanth.
Transformer operates when both circuits take effect of mutual induction. Transformer company to understand, design, manufacture and support to your exact specifications and requirements. K factor transformers are specially assembled with a double sized neutral conductor, heavier gauge copper and either change the geometry of their conductors or use multiple conductors for the coils. Transformer equation notes this file contains a more detailed derivation of the transformer equations than the notes or the experiment 3 writeup. Power transformer k factor understand the importance of power transformers k factor and follow these simple steps to verify transformer content and load. To find the correct k factor transformer calculate the load and then find a k factor of equal or higher value. Kfactor transformers are specially assembled with a double sized neutral conductor, heavier gauge copper and either change the geometry of their conductors or use. Mar 16, 2015 a transformer of k4 can supply loads with higher k rating for a short period of time. K factor transformers are manufactured with the same highquality construction features as other ventilated transformer products, including standard nema 2 enclosures.
I2 2 if winding 2 is shorted, v2 becomes zero so equation 2 becomes. It will help you to understand what assumptions were needed while deriving the ideal transformer equations we use. Harmonic spectrum of the recorded values are produced in figure 2. Since 1985 a new range of voltage stabilisers up to 500kva has been introduced.
For example, eliminating the loading problems in item 1 above is just a matter of properly specifying the transformers and specifying the k factor or the harmonic loading. Rating of transformers supplying harmonic rich loads. Mks mksh single phase kfactor dry type distribution. Hammond kfactor transformer sales, hammond transformers. Dry type distribution transformers emerson electric. Transformers come in basic kfactors such as 4, 9, 20, 30, 40, and 50. Loading transformers with non sinusoidal currents kfactor. Underwriters laboratories recognized the problems with derating. What is k factor and what does it mean regarding transformers.
Dry type distribution transformers solahd k factor transformers are designed to reduce the heating effects of harmonic currents created by loads like those shown in chart a. Kfactor srl is one of the leading worlds manufacturers of small industrial transformers up to 500kva. Mk mkh three phase kfactor dry type distribution transformer. K factor is defined as a ratio between the additional losses due to harmonics and the eddy current losses at 50 hz. Features specially designed core and coils have reduced induction levels, resulting in a reduction in stray losses. Barrere exality corporation a transformer with individual winding inductances l1 and l2 has mutual inductance m between the windings. When k is 1, the influence of one inductor in the transformer on the other is unrealistically ideal.
Nonlinear loads cause harmonics, which in turn cause additional losses in the transformer. K factor transformer, also known as k rated transformer, is designed for nonlinear or harmonic generating loads that a standard transformer could not adequately handle due to overheating. Krated transformer manufacturers mumbai india neelkanth power. Conductors capable of carrying the harmonic currents of nonlinear loads. Transformer definition, a person or thing that transforms. Excessive 5th is of particular concern because it is negative sequence. As a result, the transformer can be sized to the load without derating. Current flowing through the transformer consists of two components. When transformers use a k factor value, they are said to be k rated. Microsoft word t6 harmonics harmonic component filter. Ms msh single phase mt mth three phase amth three phase aluminum mk mkh three phase kfactor mks mksh single phase kfactor mdi mdih three phase drive isolation mswp mswph.
To do the derivation, we will use the figure pictured below. It is the load that determines the k factor of the specific transformer. The strategy is to calculate the kfactor for your load and then specify a transformer with a kfactor of an equal or higher value. Determination of transformer rating 52 temperature increases also reduce the power factor, productivity, efficiency, capacity and performance of the plant. The onyx kfactor power distribution transformer is a premium grade isolation transformer designed for powering critical loads. If the current is low compared to the 60 hz transformer rating, the kfactor may not be an issue. The main principle of operation of a transformer is mutual inductance between two circuits which is linked by a common magnetic flux. This is a measure of the transformer s ability to withstand the heating effects of nonsinusoidal harmonic currents produced by much of todays electronic equipment and certain electrical equipment. The k factor rating is an index of the transformer s ability to withstand harmonic content while operating within the temperature limits of its insulating system. Unbalance voltage causes approximately 6 times higher level of current unbalance 1% of voltage unbalance equal to 6% of current unbalance. The spectrum of k factor can be analyzed to decide about the requirement of a k rated transformer. Once the kfactor is determined, it is used in the design of the transformer to compensate for the additional heating effects generated by the harmonic.
Aug 04, 2011 the rationale is to first compute the k factor of the load. The measurements of harmonics are indicated in tablei. Mathematically, we will define m by the following expression. The solahd kfactor design is a specialized transformer that offers these benefits. Mgms threephase liquidfilled secondary substation transformers are specifically designed to. Equivalence table between k factor ul 1562 and over rating factor, factor k hd 538 thd 0. Voltage transformation ratio k from the above equations we get. Specifically designed and engineered for safe, efficient handling of nonlinear loads created by computers, video display terminals, electronic ballasts, fax and copy machines and programmable controllers. For example, eliminating the loading problems in item 1 above is just a matter of properly specifying the transformers and specifying the kfactor or the harmonic loading. See dropdown menu for full range of kva, inputoutput voltage options.
K factor transformers come in k factors of 4, 9, 20, 30, 40, and 50. Current transformers principle of operation of ct a current transformer is defined as as an instrument transformer in which the secondary current is substantially proportional to the primary current under normal conditions of operation and differs in phase from it by an angle which is approximately zero for an appropriate direction of the connections. Common power quality factors affecting transformers mouser. The primary coil, which receives energy from the ac source. E l liquidfilled secondary l substation transformers. Once the k factor is determined, it is used in the design of the transformer to compensate for the additional heating effects generated by the harmonic currents. A kfactor rated transformer is one which is used to deal with harmonic generating loads. The onyx k factor power distribution transformer is a premium grade isolation transformer designed for powering critical loads. Vantran can meet all your transformer manufacturing needs with our quality polemount, padmount, substation transformers and more. Kfactor are focused on derating a transformer to serve a nonlinear load, rather. Some transformers liquid and drytype are now being offered with what is called a kfactor rating. Kfactor rated transformer for deal with harmonic generating. In the data center floortype pdu, the commonly available choices are k1, k and k20.
A study of k factor power transformer characteristics by modeling simulation article pdf available in engineering, technology and applied science research 15 october 2011 with 3,714 reads. However, since the data center load is almost entirely nonlinear, the longterm operating costs are lower. Recent improvements in kfactor models yixin zhang neetrac, georgia institute of technology 2014 ieee pes panel session discussions on ieee std. The alternative approaches for power distribution transformers using kfactor and. Kfactor kfactor determines the total harmonic current which a transformer can withstand without going beyond its specified temperature threshold limits. Transformer cant stepup or stepdown the level of dc voltage or dc current. When transformers use a kfactor value, they are said to be k rated. Kfactor rated transformers electrical harmonics eaton. K 20 is the preferred choice for data centers but carries the highest price tag. Technical guide the mvlv transformer substations abb group. A case study for selection and sizing of k rated isolation. Some transformers liquid and drytype are now being offered with what is called a k factor rating.
The ratio of the maximum coincident demand of a system, or part of a system, to the total connected load of the system. Under normal circumstances the value of k factor ranges from 150. Order transformer acme transformers fingerguard itrap krated transformers three phase transformers dry type distribution and control transformers. Since 1985 a new range of voltage stabilisers up to 500kva has. Kfactor rated threephase transformers are available with. Apr 16, 2011 current transformers principle of operation of ct a current transformer is defined as as an instrument transformer in which the secondary current is substantially proportional to the primary current under normal conditions of operation and differs in phase from it by an angle which is approximately zero for an appropriate direction of the connections. It is more economical to purchase a k factor transformer than using a derated oversized transformer. Eaton k factor nonlinear transformers are specifically. K factor srl is one of the leading worlds manufacturers of small industrial transformers up to 500kva. Magnetizing current im which is in quadrature 900 to the applied voltage and in phase current which is in phase to the applied voltage. Production has been also extended to voltage adapters, regulators, frequency converters and various protection systems. It is important to have systems in place to monitor and analyze the power quality issues that can affect critical and expensive components in a power distribution system. A case study for selection and sizing of k rated isolation transformers in parallel redundant ups system.
Note that the k8 curve is almost identical to the nema derating curve. Hammond kfactor transformer sales, hammond transformers on sale. Kfactor transformers your data center cooling solutions. In this standard, the kfactor is defined and its method of calculation shown. Common power quality factors affecting transformers. Transformers with a rated k factor of 4, 7, 20 and 30 are available. Transformer only stepup or stepdown the level of ac voltage or ac current. The window space factor k w is defined as the ratio of copper area in window. Eaton s k factor transformers address the problems caused by nonlinear loads and harmonics. To determine the connection scheme the following factors must be taken into. Kfactor srl transformers, voltage stabilisers, protecion. In this standard, the k factor is defined and its method of calculation shown.
This constant k is known as voltage transformation ratio. In this way, the transformer can be sized to the load without derating. The k1 transformer is not designed for nonlinear loads but is available as the lowestcost. In other words, the kfactor of the overall load is less than that which would be. Power factior is the ratio of real power flowing to the load and apparent power to the circuit. A basic transformer consists of two coils that are electrically separate and inductive, but are magnetically linked through a path of reluctance. Though the heat generated will be high but a period of relatively low load will give transformer time to dissipate the extra heat generated. This means that all of the inductance from one pulls down on the other. K factor is a measure of current distortion in the load fed by a transformer. Transformer basicsworking principle,construction,types. They also compensate for stresses on a transformers winding insulation which prevents insulation breakdown and premature failure. A study of kfactor power transformer characteristics by modeling simulation article pdf available in engineering, technology and applied science research 15 october 2011 with 3,714 reads.
Pay attention to the amount of current rms value that is involved in large k factor measurements. Demand factordiversity factorutilization factorload. The transformer the principle parts of a transformer and their functions are. K factor k factor determines the total harmonic current which a transformer can withstand without going beyond its specified temperature threshold limits.
In the stepup transformer, the lowvoltage side is connected to the input, or primary, side. Determination of transformer rating based on total harmonic. K rated transformers are available as a possible solution to the problem of harmonic energy that might damage a standard transformer. Periodic capture waveforms are preferred for k factor calculation. Krating of transformers there are two approaches to rating transformers supplying harmonic rich load. K factor is a weighting of the harmonic load currents according to their effects on transformer heating, as derived from ansiieee c57. Demand factor maximum demand total connected load for example, an over sized. Pdf a study of kfactor power transformer characteristics. It is used to evaluate transformers for nonlinear loads. It is the load that determines the kfactor of the specific transformer.
The use of a k rated transformer is anywhere nonlinear loads are present. Kfactor transformer, also known as krated transformer, is designed for nonlinear or harmonic generating loads that a standard transformer could not adequately handle due to overheating. K factor transformers have to manage continuous thermal stresses caused from harmonics and excessive neutral currents. For a particular application, the turns ratio,a, is. Kfactor transformers for low voltage electrical harmonics. Harmonics generate additional heat in the transformer and cause nonkrated transformers to overheat possibly causing a. Applies to ventilated type transformers by squaredschneider electric. What is the power factor of transformer under no load. The higher the k factor, the greater the harmonic heating effects.
Power transformer kfactor understand the importance of power transformers kfactor and follow these simple steps to verify transformer content and load. The appropriate k factor for studied transformer should be 4. Onyx k factor transformers include an expanded steel core for a k 20. K factor of 1 is used for linear loads only, and a k factor of 50 is used for the harshest harmonic environment possible. The k factor transformers are made especially for nonlinear loads and the extra heating caused by the harmonic currents. Kfactor transformers are manufactured with the same highquality construction features as other ventilated transformer products, including standard nema 2 enclosures.
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