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The power of all three phases can be transmitted on three conductors.

A star connection, as opposed to a delta, provides a grounding reference. Also, for ground faults on the secondary (assuming no delta third winding, or source third winding) will be a direct ratio similar to phase faults, instead of 57%. Another reason is to avoid the inherent phase shift involved in a delta/star configured transformer.

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A 'star-connected' secondary is the standard European connection for a three-phase distribution transformer, as it provides a line voltage of 400 V together with a phase voltage (i.e. line to neutral) of 230 V.

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10y ago
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11y ago

A star-delta connection is used in transformer connection for below described reasons:

1. During transmission, the Star connection of Transformer is kept at Transmission side as Phase voltage in star connection is equal to 1/√3 times of line voltage and hence the insulation required is very less as compared if delta is kept at transmission side.

By this connection there will be a phase shift of 30deg in the primary and secondary voltages.

So this connection saves a lot of money on insulation and in this connection the neutral of Star connection is grounded as a result earth plays a role of reference for checking balancing of phase.

2. During Distribution, at Sub-station side Star-Star connected transformer is used and at lower distribution Delta-Star connection is used to compensate the phase shift and also to have a three phase four wire system at distribution end.

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Q: Why is star connection used in a three phase transformer?
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How do you take a single phase output by giving 2phase input in transformer?

You are not really connecting two phases to the primary of the transformer; you are connecting one phase. In delta configuration, each phase is actually the connection of two legs, AB, BC, and CA. Even though you are connecting two legs to the transformer, there is only one phase involved. In star configuration, however, each phase is the connection of one leg to neutral, AN, BN, and CN. In star, you would only use one of AN, BN, or CN to connect to the transformer's primary winding. Star configuration is preferred, and is actually used in the transmission/distribution system, because in delta, loss of one leg takes out two phases. Star configuration, however, would not be preferred if your local distribution was based on a non-centered neutral, such as a quadraplex connection providing split phase simultaneously with three phase. (120/240-240/3) The neutral in that case is not at the center of the star triangle - it would be at the center of one of the phase pairs.


How do you get two different voltages using the delta - star connection?

A star connection is where the three phase nonpolarities are tied to a single point, and very often grounded. A delta connection is where the nonpolarity of one phase is tied to the polarity of another phase, forming a greek delta shape. If measuring from polarity to nonpolarity on a single phase, in the star formation you are looking at L-N voltages; in the delta connection, you are looking at L-L voltages (L-N voltages * square root of three).


How can three types of supply be obtained from the secondary side of a delta star transformer where the supply voltage is 11000 V?

The standard three-phase distribution transformer in the UK is a delta/star connection with a rated primary line voltage of 11 kV, and a nominal secondary line voltage of 400 V, giving a secondary phase voltage of 230 V.So, the secondary provides a three-phase, four-wire, system comprising three line conductors and a neutral conductor. The line-to-line (line voltage) voltage is 400 V and the line-to-neutral (phase voltage) voltage is 230 V.There are not 'three types' of supply obtained from this arrangement.


What is the difference between star delta and wye delta?

With a delta connection, picture a triangle. Each side of the triangle is a transformer or motor winding. Call the 3 corners of the triangle A, B, and C. There are only 3 wires except for a safety ground, which has no connection to, nor is any part of, the power transmission service lines.but for the star connection take our triangle above and use your wire cutters (literally) to cut the triangle apart at the corners. rearrange the three sides (transformer or motor windings) to form a Y. Where the three sides join in the centre, connect a fourth wire. Call this wire "neutral". Call the three ends A, B, and C. Connect the 3 supply service lines to A, B, and C.


Where do you use star-star connection in electrical system?

i think its use for 3 phase connection.

Related questions

What is The Connection in three phase transformer?

the connection here meant for the connection of windings in three core or limbs of a transformer. it might be delta or star connected.


Is there a neutral on a three phase transformer?

It depends on whether you are wye or delta connected. A transformer is a transformer, and a three phase transformer is simply three transformers. The key is in how you hook them up.AnswerIt depends on how the transformer is connected. If one set of windings is connected in star (or wye), then the star point is/canbe earthed and becomes the neutral for that particular connection; this is the standard connection for the secondary (low-voltage) of European distribution transformers. In North American three-phase distribution transformers, the secondary windings are connected in delta, and one phase is centre tapped, earthed, and that becomes the neutral point for a 240/120-V split-phase supply to a residence.This answer applies to both three-phase transformers, and to single-phase transformers which have been connected to form a three-phase transformer bank. (It is incorrect to say that a three-phase transformer is simply three single-phase transformers!)


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.


Star-star connection of transformer?

Star Star TransformerStar Star Transformer is formed in a 3 phase transformer by connecting one terminal of each phase of individual side, together. The common terminal is indicated by suffix 1 in the figure below. If terminal with suffix 1 in both primary and secondary are used as common terminal, voltages of primary and secondary are in same phase. That is why this connection is called zero degree connection or 0o - connection.If the terminals with suffix 1 is connected together in HV side as common point and the terminals with suffix 2 in LV side are connected together as common point, the voltages in primary and secondary will be in opposite phase. Hence, Star Star Transformer connection is called 180o - Connection, of three phase transformer.Vikram Meena


Why you use delta star transformer instead of star star transformer in a consumer plant?

Generally speaking high-voltage three-phase systems are three-wire systems comprising three line conductors, so the high-voltage primary of the transformer is delta-connected (a delta connection has only three terminals, to which the three line conductors are connected). European low-voltage three-phase systems are four-wire systems, comprising three line conductors and a neutral conductor. To obtain this, the transformer's secondary must be star (wye) connected, with its earthed star point providing the neutral.


In a 3-phase high voltage star-star connection 140KVA transformer and load phase voltage is 115v and frequency is 400hz what is the total load current?

Maximum load current on a 140KVA, three phase transformer when the output voltage is 115 v phase to phase is: 140kva / sqrt (3) / 115 = 703 Amps. frequency does not matter here.


What is DY11 transformer?

d:delta connection primary windingy :star connection secondary winding


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.


How do you take a single phase output by giving 2phase input in transformer?

You are not really connecting two phases to the primary of the transformer; you are connecting one phase. In delta configuration, each phase is actually the connection of two legs, AB, BC, and CA. Even though you are connecting two legs to the transformer, there is only one phase involved. In star configuration, however, each phase is the connection of one leg to neutral, AN, BN, and CN. In star, you would only use one of AN, BN, or CN to connect to the transformer's primary winding. Star configuration is preferred, and is actually used in the transmission/distribution system, because in delta, loss of one leg takes out two phases. Star configuration, however, would not be preferred if your local distribution was based on a non-centered neutral, such as a quadraplex connection providing split phase simultaneously with three phase. (120/240-240/3) The neutral in that case is not at the center of the star triangle - it would be at the center of one of the phase pairs.


How do you wire a three phase motor with two speed?

Star and delta connection


Why most of the 3-Phase transformer use Y connection instead of Delta Connection?

This is certainly the case in the UK, where a three-phase distribution transformer's secondary windings are wye, or 'star', connected. The reason is that it provides a four wire distribution system comprising three line conductors and a neutral conductor, operating at 400 V line-to-line and 230 V line-to-neutral which enables the provision of single-phase 230-V services to residential loads (line-to-neutral connection) and a 400/230-V three-phase supply to small businesses if required.


Why is a three phase four wire distribution system used?

A three phase four wire system allows for two voltages from a single three phase transformer. The transformer configuration is a wye or star connection. It is used in commercial and industrial applications. Apartment buildings are now starting to use a three phase four wire service distribution system. Some wye connection voltages are 120/208 volts, 480/277, and 600/347. The lower voltage is derived from the sq root of 3 divided into the three phase voltage.