Download transformer calculator coils and wire thickness. Kfactor rated transformers electrical harmonics eaton. A kfactor rated transformer is designed to handle a degree of harmonic load currents without overheating. I came across a community sponsored application that will aid any sheet metal designer. It has two types, single phase and three phase transformer. Laboratories in the united states, is to calculate the factor increase in eddy. As the k factor of the transformer increases, generally the size and cost increase, low load efficiency k factor transformers are designed to withstand the extra heating and higher neutral currents caused by harmonics created by nonlinear loads such as vfd, dc power supplies and led lighting. Transformers with a rated k factor of 4, 7, 20 and 30 are available. Pdf a study of kfactor power transformer characteristics by. Neel industrial systems k rated isolation transformer. There are many different loads such as computers, solidstate devices and motors which cause a non linear load. Loading transformers with non sinusoidal currents kfactor. If you dont know anything about assembling transformers, please dont use calculations from this program for building your own transformer.
The kfactor transformer power quality in electrical systems. Kfactor can be a misleading power quality indicator. Power and distribution transformers sizing calculations. The higher the k factor, the greater the harmonic heating effects. Transformer capacity calculator three phase transformer. The online free fabrication calculator will help you calculate the k factor, y factor, bend allowance, bend deduction, flat size, neutral axis, arc length etc. Transformers course to be more familiar with the contents of our new articles about the power and distribution transformers sizing calculations. K factor distribution transformers in north america are subject to minimum efficiency regulations in both the u.
Reasons for selecting pqi hmts in lieu of k factor rated transformers. For example, a k transformer can be fully loaded with any harmonic load having a k factor up to k. Alfa transformer stocks remanufactured and reconditioned, threephase, medium voltage dry type transformers through 2500 kva. Collection of formulas for umg measurement devices janitza. Kfactor measures the heating effects of harmonics on transformer loading and losses. Kfactor transformers are specially designed to accommodate harmonic.
Harmonics generate additional heat in the transformer and cause non k rated transformers to overheat possibly causing a fire, also reducing the life of the transformer. Nowadays, in industrial workplaces, the proliferation of solidstate devices lighting reactors, motor drive and control systems, communications equipments, and other dc motor loads have created some relevant problems for specification engineering, contractors and business owners. Today, we will explain other special cases for power and distribution transformers sizing calculations. Miscellaneous documents power quality international. Kfactor 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. These type ql transformers have passed the ul k factor testing program. K factor is the right company, iso9001 certified, reliable and. A study of k factor power transformer characteristics by modeling simulation. Factor k in europe, the transformer derating factor is calculated according to the formulae in bs 7821 part 4. All sheet metal workers know the importance of an accurate k factor or bend allowance when it comes to design. Calculating overcurrent protection device rating 3.
The blakley calculator allows you to carry out various electrical calculations. A transformer with k factor 9 should be specified when 100% of the load is nonlinear. Once the k factor of the load has been determined, it is a simple matter to specify a transformer with a higher k rating from the standard range of 4, 9, 20, 30, 40, 50. K factor must be determined to calculate the right size transformer that is needed. K peak responsibility factor which is the ratio of transformer load at the time of the system peak to the transformer peak load.
To download your copy of transformer calculations spreadsheet, click on the link. Explains why hmts can be better than k rated transformers. Determination of transformer rating based on total. The harmonic analysis module also offers the transformer kfactor ansiiec and factork bs calculation for the assessment of transformer rating with respect. Tti three phase isolation transformers from 1 to 40kva. The transformer losses will increase while it is supplying nonlinear load current. K factor is a weighting of the harmonic load currents according to their effects on transformer heating, as derived from ansiieee c57. K factor calculation depends upon the fundamental current and the harmonic current components, and it is an indicative value of the harmonic contents in the power system. No load losses of a distribution transformer under harmonic loads can increase its operating cost. Only the fundamental oscillation is used in order to calculate the cosphi. Are you looking for the best transformer calculator software for your next project. Find, read and cite all the research you need on researchgate.
Determination of transformer rating 52 temperature increases also reduce the power factor, productivity, efficiency, capacity and performance of the plant. The k factor rating is an index of the transformers ability to withstand harmonic content while operating within the temperature limits of its insulating system. As long as the load k factor is lower than the k rating of the transformer, the full kva rating of the transformer can. A kfactor rated transformer is one which is used to deal with harmonic generating loads.
The derating measure for normal transformers is always taken to limit the temperature of windings or topoil. Electrical ms excel spreadsheets electrical engineering portal. An online three phase transformer calculator to find the current in different power units. Rus bulletin 1724e301 guide for the evaluation of large. 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. This k factor has absolutely nothing to do with the k factor used to determining the suitability of a transformer for use in a circuit with high harmonic levels. Standard and custom designs through 10 mva, up to 35kv. It is important to note, however, that these solutions are best only for those experts who have knowledge and experience with assembly transformers.
In the case of sinusoidal loading of the transformer the k factor 1. Significance of k factor k factor of the electrical distribution network is the reason why transformers need to be derated. By downloading this spreadsheet you agree to the following terms. The k factor 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. Calculating overcurrent protection device rating on the low voltage side of the transformer. Power and distribution transformers sizing calculations part seven. Power transformer kfactor understand the importance of power transformers k factor and follow these simple steps to verify transformer content and load. Mks mksh single phase kfactor dry type distribution. A specific k factor rating indicates that a transformer can supply its rated kva load output to a load with a specified amount of harmonic content. A study of kfactor power transformer characteristics by. Transformer calculation is program for calculating number of coils and wire thickness at transformer. 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. Significance of k factor in circuit breaker ratings powell industries, inc. There are two widely used methods to calculate the kfactor.
Lft transformer loss factor which is the ratio of average transformer losses to peak transformer losses. In this standard, the k factor is defined and its method of calculation shown. Barrere exality corporation a transformer with individual winding inductances l1 and l2 has mutual inductance m between the windings. 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. Short answer is the k factor conveys a transformers ability to serve varying degrees of nonlinear loads without exceeding the rated temperature rise limits. In this paper, the formulations how to calculate the maximum permissible rms nonsinusoidal load current i max using the harmonic loss factors f hl and k factor were introduced. Calculating the prospective short circuit current 4. 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. The kfactor transformer power quality in electrical. A k factor transformer is designed to handle harmonic content in its load current without exceeding its operating temperature limits.
If you have some experience in assembling transformers, then this program is perfect for you. In short, k factor is a weighting of the harmonic load currents according to their effects on transformer heating, as derived from ansiieee c57. As from the formula, while calculating the kfactor, the harmonic current is getting multiplied by the square of its number. Calculating the prospective short circuit current across the low voltage side of the transformer. The k factor transformer is an isolating transformer that can be loaded at 100% of load plus the harmonics load without overheating.
K factor is a unit measuring a transformer s ability to withstand the harmonics content of a system. The k rating number of the transformer 1, 4, 9, 20 is in indication of the amount of harmonic current the transformer is capable of handling. A case study for selection and sizing of k rated isolation transformers in parallel redundant ups system. What is k factor and what does it mean regarding transformers. Equivalence table between k factor ul 1562 and over rating factor. 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. Underwriters laboratories recognized the problems with derating.
To download your copy of transformer calculations spreadsheet, click on. Sola kfactor transformers are designed to reduce the heating effects of harmonic currents. Power factor correction calculations for power system new star. While supplying the nonlinear loads, harmonic currents flow in the transformer and to protect the windings and transformer oil from overheating, load on it needs to be reduced. Visit our website to view the publications listed below, download the software. To increasedecrease the alternating volts in electric power, transformers are used. Alfa offers a complete range of new and reconditioned low voltage dry type transformers including general purpose, drive isolation, motorstarting autotransformers. Comparing transformer derating computed using the harmonic. Professionals with experience in transformer assemblies use the computer program to calculate the number of coils and wire thickness. Calculate size of transformer and voltage due to starting of large size motor new.