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delta star
A star winding has a red yellow and blue phases. The centre point of every stay winding is used as d nuetral point. Hence the star winding in a transformer enables a nuetral point.
by using Y-Y(Star) transformer..... bcoz in star VL = root 3* Vph
Line to Ground voltage = line to line voltage / 1.73AnswerIt depends what configuration is being measured. In the case of the secondary of a split-phase distribution transformer used to supply residences in North America, the answer is yes. In the case of a star (wye) connected secondary distribution transformer used to supply residences in Europe, no: the line to ground voltage will be as described in the first answer.
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.
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 distribution transformer's star-connected secondary, the common point of connection is called the 'star point' and is connected to earth. The star point then provides the neutral connection for the transformer secondary, providing a return path for any unbalanced currents due to an unbalanced three-phase load.This arrangement provides a four-wire distribution system, comprising three line conductors and one neutral conductor (in addition, there are various methods of providing an earth connection to consumers). The line-to-line voltage is called a line voltage (in the UK, 400 V), while a line-to-neutral voltage is called a phase voltage (in the UK, 230 V). The line voltage being 1.732 x phase voltage.
In the transformer at the secondry side one end of the winding will make star connection means 0 point there will be no voltage at that end if any leake voltage appear at that point it have to ground that what all the neutral points to be grounded
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.
delta star
A star winding has a red yellow and blue phases. The centre point of every stay winding is used as d nuetral point. Hence the star winding in a transformer enables a nuetral point.
by using Y-Y(Star) transformer..... bcoz in star VL = root 3* Vph
The voltage phase shift between primary and secondary connections in a transformer is 180 electrical degrees.
The term, 'star point', refers to the common point of connection for the three windings of a star-connected (wye-connected) transformer connection. The star point is usually earthed (grounded) and provides the neutral point of the connection.
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.
In the case of a step-down transformer, the secondary winding is earthed (grounded) to provide protection against an insulation breakdown between the high voltage and low voltage windings -in other words to deliberately cause an earth fault that will initiate the operation of the high-voltage system's protection system. At the same time, it provides a zero-potential point of reference for all potentials measured on the low-voltage system, and a means by which earth-fault currents can return to the source. In the case of a three-phase transformer supplying an unbalanced load, an unearthed star-point will result in a 'floating neutral', which means that the three phase voltages will likely be unbalanced (i.e. different from each other).
No. A 277 volt ballast needs the correct voltage to operate. The 277 voltage is derived from the star point voltage of a 480 volt three phase system (277/480). The 208 voltage is a three phase line voltage whose star-point voltage is 120 volts (120/208).