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Selection of vector group of a transformer?
Generally for export only transformer, generator side is connected in delta and load side is connected in star. For export import transformers star star connection may be preferred by some since this avoids a grounding transformer on generator side and perhaps save on neutral insulation. I am not sure how correct this practice is but so many systems are running in this configuration. Perhaps it may be felt to be less harmful than operating delta system incorrectly. Yd or Dy connection is standard for all unit connected generators. The main reasons for connecting generator side winding in delta are: 1) To facilitate grounding of generator system with higher impedance and the load system with lower impedance. 2)To break The zero sequence circuit for the system at the transformer. This ensures the load side zero sequence currents do not come to the generator system. 3) III rd and similar harmonics will circulate in delta and will not come to generator system. The trafo vector group will be Dy if load voltage is lower and Yd if load side voltage is higher. Dy1,5,7 or 11 selection depends on requirement for load synchronizing ,standardizing or ready trafo availability. All vector groups are functionally similar.
What type of transformer has only a single winding?
the auto transformer is the one winding transformer. it ismaily used in practical purpose.
What is the main different between the power transformer and voltage transformer?
Voltage Tarnsformer transforms only voltage. While power transformer transforms both voltage and current.
What causes a low voltage in the transformer?
If this refers to a wire wound transformer, as it sounds then there is likely only two possibilities : the input voltage has dropped prier to entering the primary windings or there is a short in the windings some where within.The only other possibility I can think of is : This is a trick question and the transformer is a step down transformer.
Why the open and short ckt test of transformer is needed?
The open/short-circuit test on a transformer isn't 'needed'. It's only used if you want to find out the efficiency of a transformer.
Can a step up transformer work as a step down transformer?
Sure. The description only depends on which side gets the excitation and which side provides the output. Excite the shorter winding and you have a step-up. Excite the longer winding and you have a step-down.
Why does excitation energy increase down the group for 1st group alkali metals?
Excitation energy for any 2 atoms is compared only for those electrons in the same energy shell.so as we go down the group the energy required to promote the electron in the same orbit to highest possible energy state increases due to the increase in effective nuclear charge
A transformer can only?
A transformer does many things.
Will a vector multiplied by another vector result in another vector?
It depends on the angle between the vectors (AB). The product of two vectors Av and Bv is AvBv=-Av.Bv + AvxBv= |AvBv|(-cos(Ab) + vsin(AB)). If the angle is a odd multiple of 90 degrees the product is a vector. If he angle is an even multiple of 90 degrees, the product is a scalar. If he angle is not a multiple of 90 degrees, the product of a vector by another vector is a quaternion, the sum of a scalar and a vector. Most numbers in physics and science are quaternions, a combination of scalars and vectors.Quaternions forma mathematical Group, vectors don't. The product of quaternions is always a quaternion. The product of vectors may not be a vector, it may be a vector , a scalar or both. The product of scalars is also a Group. Vector by themselves do not form a Group. The Order of Numbers are Scalars form a Group called Real Numbers; scalars and a single vector form a group called complex numbers; scalars and three vectors form a group called Quaternions. These are the only Groups that provide an Associative Division Algebra.
A transformer can only the voltage of an alternating current?
A transformer can only increase or decrease the voltage of an alternating current, and it is called step-up transformer or step-down transformer accordingly.
When will be the vector projection and vector components are same?
Ans :The Projections Of A Vector And Vector Components Can Be Equal If And Only If The Axes Are Perpendicular .
Selection of vector group of a transformer?
Generally for export only transformer, generator side is connected in delta and load side is connected in star. For export import transformers star star connection may be preferred by some since this avoids a grounding transformer on generator side and perhaps save on neutral insulation. I am not sure how correct this practice is but so many systems are running in this configuration. Perhaps it may be felt to be less harmful than operating delta system incorrectly. Yd or Dy connection is standard for all unit connected generators. The main reasons for connecting generator side winding in delta are: 1) To facilitate grounding of generator system with higher impedance and the load system with lower impedance. 2)To break The zero sequence circuit for the system at the transformer. This ensures the load side zero sequence currents do not come to the generator system. 3) III rd and similar harmonics will circulate in delta and will not come to generator system. The trafo vector group will be Dy if load voltage is lower and Yd if load side voltage is higher. Dy1,5,7 or 11 selection depends on requirement for load synchronizing ,standardizing or ready trafo availability. All vector groups are functionally similar.
If a vector quantity is divided by its magnitude the vector obtained is called?
The vector obtained by dividing a vector by its magnitude is called a unit vector. Unit vectors have a magnitude of 1 and represent only the direction of the original vector.
What type of transformer has only a single winding?
the auto transformer is the one winding transformer. it ismaily used in practical purpose.
How we select a transformer by vectorgroup?
A Vector group is the International Electrotechnical Commission (IEC) method of categorizing the primary and secondary winding configurations of three-phase transformers. Within a polyphase system power transformer it indicates the windings configurations and the difference in phase angle between them. The phase windings of a polyphase transformer can be connected together internally in different configurations, depending on what characteristics are needed from the transformer. For example, in a three-phase power system, it may be necessary to connect a three-wire system to a four-wire system, or vice versa. Because of this, transformers are manufactured with a variety of winding configurations to meet these requirements. Different combinations of winding connections will result in different phase angles between the voltages on the windings. This limits the types of transformers that can be connected between two systems, because mismatching phase angles can result in circulating current and other system disturbances. Symbol designation The vector group provides a simple way of indicating how the internal connections of a particular transformer are arranged. In the system adopted by the IEC, the vector group is indicated by a code consisting of two or three letters, followed by one or two digits. The letters indicate the winding configuration as follows: * D: Delta winding, also called a mesh winding. Each phase terminal connects to two windings, so the windings form a triangular configuration with the terminals on the points of the triangle. * Y: Wye winding, also called a star winding. Each phase terminal connects to one end of a winding, and the other end of each winding connects to the other two at a central point, so that the configuration resembles a capital letter Y. The central point may or may not be connected outside of the transformer. * Z: Zigzag winding, or interconnected star winding. Basically similar to a star winding, but the windings are arranged so that the three legs are "bent" when the phase diagram is drawn. Zigzag-wound transformers have special characteristics and are not commonly used where these characteristics are not needed. * III: Independent windings. The three windings are not interconnected inside the transformer at all, and must be connected externally. In the IEC vector group code, each letter stands for one set of windings. The HV winding is designated with a capital letter, followed by medium or low voltage windings designated with a lowercase letter. The digits following the letter codes indicate the difference in phase angle between the windings, with HV winding is taken as a reference. The number is in units of 30 degrees. For example, a transformer with a vector group of Dy1 has a delta-connected HV winding and a wye-connected LV winding. The phase angle of the LV winding leads the HV by 30 degrees. The point of confusion is in how to use this notation in a step-up transformer. As the IEC60076-1 standard has stated, the notation is HV-LV in sequence. For example, a step-up transformer with a delta-connected primary, and star-connected secondary, is not written as 'dY11', but 'Yd11'. The 11 indicates the LV phase lags 30 degree behind the HV side. Transformers built to ANSI standards usually do not have the vector group shown on their nameplate and instead a vector diagram is given to show the relationship between the primary and other windings.
What is the difference between control transformer and Potential transformer?
Control transformer used only for control supply 110,220, 24,12V AC. But Potential transformer used voltage measurement purpose.
How will you multiply a vector by positive number?
A positive scalar multiplied by a vector, will only change the vector's magnitude, not the direction. A negative scalar multiplied by the vector will reverse the direction by 180°.
