Stringent quality control has to be ensured right from selection of raw materials, manufacturing to procurement and installation of these transformers. Understand significance of vector groups interpret the vector group notations used on transformer name plates content. Parmar, while i appreciate your article on significance and selection of vector group of transformers, pl. The vector diagrams are given in the name plate details of the transformer. The transformer vector group show the phase difference between the primary and secondary sides of the transformer. Service we provide 3 years of warranty for our instruments and 10 years of spare parts availability. The connection of all the windings in a threephase transformer is indicated by a vector group symbol. This symbol indicates the winding connections and their relative phase displacement by means of a numerical index e. A bank of three singlephase transformers cost about 1. Selection criteria for vector group in power distribution. The vector group indicates the phase difference between the primary and secondary sides, introduced due to that particular configuration.
Selection of distribution transformers for supplying power to. The first letter d refers to the primary configuration being a delta. What is an interleaved connection of a transformer winding. How to determine transformer vector group a vector group is the international electrotechnical commission iec method of defining high voltage hv and low voltage lv winding configurations of threephase transformers. In case of dyn11, the secondary vector leads the primary vector by 30 degrees, where as in dy1 connection, secondary vector lags the primary vector by 30 degrees. This configuration belongs to the vector group of transformer dyn1 where the lv lags the hv by 30. The capital letters apply to the high voltage winding h. From a vector group one can determine the phaseshift between primary and secondary. If the motor is started acrosstheline with a standard starter, the transformer kva must be 212 to 3x the motor hp rating, so 75kva minimum, 112. Dv power smart test instruments for reliable electrical.
For large generator step up transformers it is yd1usa or yd11iec. Vector group test of power transformer electrical4u. Every transformer contains its own vector group as shown below figure. How do you select vector group for a particular transformer.
A vector group is the international electrotechnical commission iec method of categorizing the high voltage hv windings and low voltage lv winding. Isolation of higher order harmonics in case of inverters and converters 4 type of load. There are unique connections and vector group for various applications. The real time examples for phasor groups of transformer are given here. How to draw transformer vector group connectionelectrical. According to iec764, the value of vector group can be 0,1,2,4,5,6,7,8,10,11. These phasor groups can be better understand by the following examples. In other words the vector group of a transformer cannot aid in eliminating the harmonic content in its inrush current.
Vector groups are the iec method of categorizing the primary and secondary winding. Iec has devised the standard code for determination of transformer vector group. If started with a soft starter you can use 112 to 2x the hp as kva, so 45 or 60kva, but thats not made so its 75kva anyway. When the pairs of coils have the same winding direction, then the voltages of. Mainly, the type of transformer connections are divided in 4 below groups. Dy connection y winding nullifies 3rd harmonics, preventing it to be reflected on delta side. The noload losses are caused by the continuous reversal of magnetization of the iron core and are practically constant and independent of loading. Pdf transformer vector group test conditions k pandian. Three phase vector groups three phase supply systems consist of three independent sinusoidal voltage waveforms with a phase angle between each phase of 120, as shown in the graph. Selection of transformer vector group cr4 discussion thread. Automatic transformer turns ratio meter transformer turns. The interconnected star or zigzag transformer has each phase winding split into two halves and interconnected as shown in figure 25.
Transformer, voltage ratio, vector group, impedance, shortwhat is vector group. Vector grouping of three phase transformer part 1 youtube. The transformer vector group is indicated on the name plate of transformer by the manufacturer. Hence every electrical power transformer must undergo through vector group test of transformer at factory site for ensuring the customer specified vector group of transformer. The harmonics in a transformer are present only in the transformer inrush current predominantly 2 nd harmonic content. This transformer will step down voltage from 220 kv to 11 kv. Subscribe our electrical engineering related channel electrical academy to get the. The three phase transformer windings can be connected several ways. Going counterclockwise between h1 and x1 can give wrong. Transformer differential protection is generally quite simple, but requires the correct application and connection of current transformers and an understanding of the power transformer winding connections, characteristics and operation. So it is utmost necessary to know how the inter connections to be made to.
It is the nature of delta and star connections and there is no specific intention to use this vector group. Vector group of 3phase transformer electrical concepts. The naming convention popularly known as vector group of transformer was established by the international electrotechnical commission iec through iec 600761. Based on the windings connection, the vector group of the transformer is. Mar, 2018 this video contains vector grouping of three phase transformer for starstar and deltadelta connections.
Yd1, yd5, etc which introduces a phase shift between winding currents in multiples of 30 zero sequence current elimination set on off 3x1 matrix 3x1 matrix numerical differential protection. Jun 18, 2012 from a vector group one can determine the phaseshift between primary and secondary. Vector group of transformers transformer electric power. Transformer operation with other primary and or secondary side voltage vector matching if they are operated in parallel with existing system either on primary or secondary side or on both sides.
Some starstar transformers are equipped with a third winding connected in delta to stabilize the neutral. Dec 12, 20 if you are replacing a transformer, use the same vector group for the new transformer, otherwise the existing vts and cts used for protection and metering will not work properly. The vector group provides a simple way of indicating how the internal connections of a transformer are arranged. Singlephase transformers may be specified for hydraulic stations because of transport. Introduction 1 theoryandtestsofsinglephase transformerconnections 2 theoryandtestsoftwophase transformerconnections 12. Three phase vector groups transformers for industry. The clock method is used to produce the numerical index of the vector group.
Points to be consider while selecting of vector group. According to iec the code for vector group consist of 2 or more letters followed by one or two digits. Applicationnote how to determine transformer vector group. The following are the mostly used vector groups of transformers. What is the criteria for selection of vector group of a.
Here yy 0 will mean its both the windings are starconnected and phase displacement between primary and secondary emfs is zero degree. The only factor affecting the choice between one and the other is system. By far the most common vector configuration of three phase transformers we manufacture is the dyn11 vector group. Winding resistance measurement resistance this transformer testing method is conducted to. What is the criteria for selection of vector group of a transformer for a given application. Earthing transformer an overview sciencedirect topics. Importance and connection diagram common vector group of transformers. The vector group shows the connection of the phases of two windings of a transformer and the numerical index hour number for the phase displacement of the vectors of the two star. Performing transformer vector group test prepared by ir kamarul. Lv is connected in delta to prevent the zero sequence.
Basic idea about transformer vector group in theory of a threephase transformer works like three equal and separated singlephase transformers working separately with three phase system with. Dv power qualified engineers will gladly assist you during measurements or answer your technical questions from different areas of the electrical power market. Connections and vector groups distribution transformers the transformers listed in this guide are all threephase transformers with one set of windings connected in star wye and. Vector group test of power transformer electrical study app. Selection of vector group of a transformer answers. The vector group indicates the phase difference between the primary and secondary sides, introduced. Transformer vector group depends upon removing harmonics. Atharv deshpande, photography, electrical engineer.
Protection relay with inbuild current amplitude and vector group compensation features and also with instantaneous differential highset element for two winding power transformer and. These three voltages have been drawn relative to a common voltage reference or neutral point. In light of the windings association, the vector gathering of the transformer is resolved. Explanation and vectorgroups schmidbauer transformers. Autotransformers do not provide galvanic isolation. The secondary side of a distribution transformer must be yn or zn to provide the neutral connection, and usually the primary side connection is delta to avoid 3rd harmonics to inject to the. Vector group of 3 winding transformer cr4 discussion thread. The earthing transformer therefore provides a low reactance to 11 kv earth faults. P department of electrical and electronics engineering loyola institute of technology and science loyola nagar, thovalai, tamilnadu629302, india abstract transformer is the most important unit in an electrical distribution network. If a threephase set of voltages is applied to a y y transformer, the voltages in any phase will obe 120 apart from the voltages in any other phase. For parallel operations, one of the internal connections of all the three winding of one of the transformers on one side only either hv or lv is necessary to be changed. Nowadays the pulse number of a converter system can be up to 48. This solution can be used as well for stepup applications in pv plants based on trio inverters.
Specifying hvmv transformers at large sites for an optimized mv electrical network on the hv side of the transformer, as illustrated in figure 2. This cannot be avoided by selecting a tansformer with a particular vector group. The three stage transformer windings can be joined a few ways. Significance of vector group of transformer your electrical.
Here yy 0 will mean its both the windings are starconnected. Selection for street light luminarpart1 selection for street light luminarpart2. How do i draw vector group of transformer from winding connection. Vector groups are the iec method of categorizing the primary and secondary winding configurations of 3phase transformers. The vector group of transformer is an essential property for successful parallel operation of transformers. Transformer losses are made up of noload losses and short circuit losses. The vector group indicates the phase difference between the primary and secondary sides, introduced due to that particular configuration of transformer windings connection. Vector groups identify the winding connections and polarities of the primary and secondary.
Three phase transformer vector group and significance of. Explanation and vector groups to applicate 1 phase and 3 phase autotransformers. Consider for example a winding configuration shown in figure 4. The vector group also defines differences in phase angles between them. Why vector group of distribution transformer is dyn11. Importance and elimination of third harmonics application and selection of vector group of transformer. What is meant by vector group for transformers and why is.
The power transformer used to transfer the high voltage supply from one place to another. A vector group is the international electrotechnical commission iec method of categorizing the high voltage hv windings and low voltage lv winding configurations of threephase transformers. The end user would also have the responsibility for the. In this arrangement, the end user has a lower kwh tariff but has to specify and purchase the hvmv transformer and hv switchgear. The auxiliary transformer is a dyn11 or any other vector group transformer and can be supplied in copper or aluminium with or without an off circuit tap changer. In a transformer, when we increase the load on the secondary side, how does the impedance of the primary winding decrease to increase the curr. They assume same winding direction in both the windings and indicate corresponding pairs of terminals that gives the required vector group. The first criterion to consider in choosing a vector group for a distribution transformer for a facility is to know whether we want a deltastar or starstar. Specifying hvmv transformers at large sites for an optimized. Three phase transformer vector grouping significance. Example shows 90% power saving compared to an isolating. Dec 22, 2017 description of vector group testing of vector group bangla tutorial for power point slide go to eee practical knowledge.
Significance of vector group of transformer on the nameplate of threephase transformer vector group is printed as yy 0, dd 1 etc. It means lv winding,which is star connected written in small letters means lv side and vice versais 30 degrees lagging by hv winding which is delta. An ampereturns balance is also achieved for the lvac out of balance or earth fault conditions such that the earthing transformer with this vector grouping presents a low reactance. As shown, the hv winding is connected in delta while the lv winding is connected in wye. The vector group of the new transformer should be the one that it is designed for ynyn0 for your case.
The vector group shows the connection of the phases of two windings of a transformer and the numerical index hour number for the phase displacement of the vectors of the two star voltages. Basically transformer vector group is used to find the high voltage and low voltage windings arrangement of three phase transformers. Department of electrical and electronics engineering. Hi, all the transformers in a subtransmission network are dyn11, in another part of the network a transformer with the vector group of ynd1 is going to be used for an industrial complex. The following will tell you the suggestions with reasons. Vector group is an essential characteristics of 3 phase transformer. Selection of distribution transformers for supplying power to lv networks photo credit.
How to draw vector group of transformer from winding. Vector group test of power transformer electrical mastar. Transformer differential protection ct ratio caused current mismatch transformation ratio caused current mismatch fixed taps ltc induced current mismatch deltawye transformation of. Transformer vector group what is yd11 etc easy explanation. Vector groups the connection of all the windings in a threephase transformer is indicated by a vector group symbol. Vector group test of power transformer electrical study.