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If the secondary system is ungrounded, or the secondary system is phase shifted +/- 30 degrees from the primary. I've even seen where the secondary system was phase shifted 150 degrees, so a special transformer was installed. There might be other reasons as well - cost, matches other equipment so a spare is not required, "it's what we've always used", etc.
What else can I help you with?
What is the relationship between phase and line values of current and voltage quantities for star and delta connected systems?
A: A DELTA transformer is a 1:1 voltage transfer delta to Y IS 1:2 voltage transfer. That is for 3 phase system, If the phases are not exactly matched or the voltage is not exactly right then on a Y setup there will be circulating current at the common node.
How do you identify step up or step down transformer from phasor diagram?
Number of turnsAnswerI assume that you have a phasor diagram of a transformer, and wish to identify the primary phasors and the secondary phasors?For a three-phase transformer, this is fairly straightforward, provided the usual procedure for drawing a phasor diagram has been followed. Whenever you start to draw anysort of phasor diagram, you usually start by selecting a phasor of reference and draw that in the horizontal positive direction. For a three-phase transformer, the phasor of reference is usually the primary phase voltage A (or however else it is identified: R, red, or whatever). The remainder of the primary phase voltages are then drawn, enabling the primary line voltages to be constructed (which, in the case of a primary delta are the same as the primary phase voltages!). So if you can identify the phasor of reference, then you have identified the primary-winding phasor diagram. As the primary and secondary voltages are not usually drawn to scale, relative to each other, you can't assume a turns ratio from the phasor diagram. The labelling might also help, as high-voltage phase and line voltages are identified by upper-case letters, while low-voltage phase and line voltages are identified using lower-case letters -but, remember, these identify high- and low-voltages, not which is primary and which is secondary (primary winding is connected to supply/secondary winding is connected to load).For single-phase transformer, the phasor of reference is the flux set up in the magnetic circuit, and voltages/current phasors are drawn relative to this. In this case, the primary line and induced voltages are usually identified as V1 and E1, and the secondary induced voltage as E2 (sometimes, the Es and Vs are interchanged). Again, the lengths of the primary and secondary voltages are not necessarily to scale relative to each other.
What will cause my voltage to be higher on one phase and lower on the other?
If secondary side of the 3 phase transformer has any issue, it would result unbalanced voltage between phases. Other reason could be if the load on one phase is highly different than other phase, it also would result in unbalanced voltage.
What is the maximum neutral current for a three phase delta star system?
It is either a delta or a star, it can't be both. A delta system doesn't have a neutral so the question must be about a star system. A high neutral current happens for example when one line is disconnected, and the neutral current then equals the current in the other two lines, which is the same current as when two lines are disconnected leaving only one line.There might be ways of calculating how to make the neutral current larger by using unusual power factors, but the above is a useful working maximum that allows all four wires of a four-wire star system to be the same size.AnswerThe term, 'delta-star', refers to a three-phase transformer connection in which the primary windings are connected in delta while the secondary windings are connected in star (wye). This is the standard three-phase connection, in Europe, for distribution transformers. Single-phase loads are connected to the secondary between alternate lines and neutral, in order to try to and balance the resulting load and minimise any resulting neutral current. Obviously, however, without having any specifications supplied, it is quite impossible to answer this question.
What is no load current in transformer?
I'm not sure that it is correct to say a transformer limits current under no load (maybe it is, depending on your application).A step down transformer converts a high voltage at the primary to a lower voltage at the secondary. Under no load conditions, the secondary will be an open circuit. Since The primary current relative to the secondary current will be Np/Ns (the turns ratio, primary to secondary), and the primary voltage relative to the secondary is Ns/Np, the apparent resistance at the primary due to an open at the secondary will be (Np/Ns)^2*(open circuit). Since an open circuit is typically approximated as an infinite resistance, resistance is infinite. The turns ratio in this idealized example doesn't really matter, hence the transformer doesn't really matter (only the fact that a no load means an open secondary matters).AnswerUnder no-load conditions, the primary current is limited due to the voltage induced into the primary winding, which opposes the applied voltage (Lenz's Law).
How do you connect an earthing transformer with delta connected secondary?
You have to connect each phase (R,Y & B respectively) of earthing transformer zig zag winding to each phase of power transformer delta secondary respectively. Then the zig zag winding of earthing transformer star point to be earthed.
What is the voltage phase shift between primary and secondary line voltages in star-delta transformer connection?
The voltage phase shift between primary and secondary connections in a transformer is 180 electrical degrees.
What is phase shift in three phase transformer?
The phase shift in three-phase transformer from winding of Transformer and determine by vectorgroup of transformer such as YNd1 High voltage connect to wye Low Voltage connect to delta so L.V. lag H.V 30 degree.Answer'Phase shift' or, more accurately, 'angular displacement', is the angle between the secondary line voltages and primary line voltages of a three-phase transformer.
Is 3 phase star transformer has more winding than delta?
The # of windings in a transformer are based on the primary and secondary voltages the transformer is rated for not the way the windings are connected.
Why vector group is required?
There are various ways in which you can connect a three-phase transformer's primary and secondary windings, or in which you can connect three single-phase transformers to create a three-phase transformer bank. For example: wye-wye, wye-delta, delta-delta, delta-wye, etc.For each connection, there is a natural phase shift between the primary and secondary line voltages. This is called the angular displacement (or 'phase displacement') of the transformer connection.If you wish to parallel two three-phase transformers, or two three-phase transformer banks, then their angular displacements must be the same (there are also other requirements not relevant to this answer).A vector group is a method of specifying a three-phase transformer (or transformer bank) method of connection and its angular displacement. Transformer connections from the same group can be paralleled. Those in different groups cannot
Why we use delta-star transformer instead of star-star transformer in a consumer plant.?
There is a problem called "neutral phase shift" in star-star transformer, if we connect unbalance load(single phase load at secondary), then the phase point is shifted towards neutral. we require sinusoidal secondary voltage at secondary, for this flux must be sinusoidal. Flux will be sinusoidal, if it contains the third harmonic component of exciting current. so third harmonic current can not flow in star-star transformer. so we use delta-star transformer,in delta , third harmonic component can flow & get sinusoidal output.
How do you find angular displacement of transformer?
Angular displacement (sometimes called phase displacement) applies to three-phase transformers, whether a single three-phase transformer, or three single-phase transformers connected as three phase transformer bank. It is, to a three-phase transformer what additive/subtractive polarities are to a single-phase transformer.Angular displacement is one of a number of conditions that must be the same before two three-phase transformers (or transformer banks) are paralleled.'Angular displacement' is the angle by which the secondary line-to-line voltage lags the primary line-to-line voltage.Angular displacements for common connections are as follows:delta/delta transformers have an angular displacement of 0o or 180owye/wye transformers have an angular displacement of 0o or 180odelta/wye transformers have an angular displacement of 30o or 210owye/delta transformers have an angular displacement of 30o or 210oSo, for example, it is impossible to parallel a delta/delta or wye/wye transformer with a delta/wye or wye/delta transformer, as their angular displacements are different.Determining the angular displacement of a particular transformer configuration (wye-delta, etc.) can be done by drawing the phasor diagram for the complete transformer as follows:draw the primary phase voltagesdraw the primary line voltagesdraw the secondary phase voltagesdraw the secondary line voltagesmeasure the (angular displacement) between a secondary line voltage and its corresponding primary line voltage
What is a phase shifting transformer?
This applies to three-phase transformer connections. 'Phase shift' or 'angular displacement', is defined as 'the angle by which the secondary line-to-line voltage lags the primary line-to-line voltage'.Angular displacement depends on the type of transformer connection. The most common are:delta/delta results in an angular displacement of 0o or 180owye/wye results in an angular displacement of 0o or 180odelta/wye results in an angular displacement of 30o or 210owye/delta results in an angular displacement of 0o or 180oThe angular displacement for all possible combinations of three-phase transformer connections are listed in transformer vector group charts.Angular displacement determines whether or not it would be possible to parallel different types of three-phase transformer connections. For example, from the above data, it would be impossible to parallel, for example, a delta/delta transformer with a delta/wye transformer.
How many bushing do you get on delta to star transformer?
Your use of the word "bushings" implies you are dealing with a high-voltage transformer (over 600 volt). A three phase STEP-DOWN transformer normally has 3 bushings on the Primary side regardless of whether it is star-delta or another type. The Secondary side might have 3 or 4. A single phase transformer normally has 2 bushings on the Primary side and 2 or 3 on the Secondary side. If the transformer is being used to STEP-UP, it would be reversed from above. If this does not answer your question, I need more info.
Can you replace DY11 by DYN11 transformer?
Yes, you can replace a DY11 transformer with a DYN11 transformer, but it is important to consider the differences in their winding configurations and phase shifts. The DY11 transformer has a wye (star) connection on the primary side and a delta connection on the secondary side, while the DYN11 transformer has a delta connection on the primary side and a wye connection on the secondary. This change in configuration may affect voltage levels and phase relationships in your system, so it's essential to ensure compatibility with existing equipment and load requirements. Always consult with an electrical engineer before making such a replacement.
How do you tell if you have delta or wye power?
In Europe, low-voltage three-phase distribution is by means of a four-wire system (three line conductors and a neutral) supplied from a wye-connected transformer secondary. In North America, low-voltage is supplied from a delta-connected transformer secondary, one phase of which is centre-tapped and earthed (grounded). The single-phase supply to residences is then supplied by that particular phase, giving 240 V line-to-line and 120 V line-to-neutral. You can tell if you have a delta power when the phase voltage is equal to the line voltage and that you have a star power when the phase voltage =root 3(THE LINE VOLTAGE).
What are the problems associated with the three-phase transformer connection?
One must check the design of the transformer windings. STAR - Delta or Star to star or Delta - star or Delta Delta. Wiring must be done accordingly.
