Basic Guide Of Delta Transformer

The delta transformers produced by Beijing Daelim are of safe and reliable quality, and the materials and accessories required for production are strictly controlled. Therefore, the transformers we produce can provide safe and stable power to ensure all continuous and stable power usage in industrial and other fields. Secondly, the appearance design of the delta transformers produced by Daelim is very simple and stylish, the color is gray or the color specified by the customer, and it can be placed in outdoor places. Finally, Beijing Daelim provides considerate after-sales maintenance services, and customers can enjoy two years or more warranty services to ensure that the transformers can operate well without very frequent replacements.

What does delta mean on a transformer?

Delta is the fourth Greek letter. In mathematics or physics, it is usually used to indicate the amount of change. In the power system, the Delta connection is generally called three-phase three-wire system. And Delta connection system is often used for AC power transmission. For power distribution systems, Wye connection is usually used. Delta is the permutation and combination of three passive components. These three passive components can be the same or different. Delta connection can also be called mesh connection. They are in the same connection mode. The three passive components are connected to each other in pairs, and the two connection points of the passive components provide input power.

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Basic two connection modes of transformers

The wiring method of the transformer is actually a simple and efficient representation of the wiring form of the primary winding and the secondary winding of the transformer;

Generally speaking, there are two basic connection methods for transformer windings, namely "delta connection" and "wye connection". In the connection group of transformers, Y means wye connection, D means delta connection, and n means neutral connection; "11" means that the line voltage Uab on the secondary side of the transformer lags the line voltage UAB on the primary side by 330 degrees.

The representation method of the connection group of the transformer: uppercase letters indicate the connection method of high voltage, and lowercase letters indicate the connection method of low voltage. Y (or y) is the wye connection and D (or d) is the delta connection.

The combination of the primary winding and the secondary winding of the transformer forms four wiring groups: D, d, D, y, Y, y, Y, and d. Only Y, y, and Y, d are used in my country. Since there are two connection methods with neutral line and without neutral line when connecting Y if no symbol is added, it means that there is no neutral line, and if the letter Y is followed by the letter n, it means that it has a neutral line. n means that the neutral point has a lead wire.

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Three-phase transformer connection methods

Three-phase transformers have four connection methods: Star-Star (Y-Y), Delta-Delta (Δ-Δ), Star-Delta OR Wye-Delta (Y-Δ), Delta-Star OR Delta-Wye (Δ-Y). Choose according to the application scenarios of the transformer.

The three-phase transformer is composed of three independent windings, through different connection methods (such as star, and delta), so that it can input and output three-phase AC power. Three single-phase transformers of the same capacity are combined to form a three-phase transformer group, which has the same function and function as the three-phase transformer.

The three-phase transformer has three core legs and each core leg is wound with two coils, one is a high-voltage coil and the other is a low-voltage coil. Three-phase power is a generator that generates potentials with equal amplitude, equal frequency, and 120° phase difference, called three-phase generator; using the three-phase generator as the power source, called three-phase power source; circuit powered by three-phase power source, called three-phase circuit. U, V, and W are called three-phase, and the voltage between the phases is the line voltage, and the voltage is 380V. The phase voltage between the phase and the center line is called the phase voltage, and the voltage is 220V.

Three-phase transformers are widely used in industries, mining, railways, construction sites, schools, hospitals, hotels, and other places, as well as precision machine tools, mechanical and electronic equipment, medical equipment, etc.

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What is the difference between a Delta and Y connection?

Take high-voltage winding as an example, wye connection is to connect the ends of three-phase windings together to form neutral points and lead out the heads of three-phase windings respectively. When drawing wiring diagram, the three-phase windings should be drawn vertically and parallel, with the phase sequence from left to right, the positive direction of potential from the end to the head, and the opposite voltage direction. When drawing phasor diagram, the potential of phase B should be drawn vertically, and the other two phases are arranged clockwise with a difference of 120. The direction of the three-phase potential points from the end to the head and the line potential also points from the end to the head.

Delta connection is to connect the head and end of three-phase winding into a closed loop in sequence and lead out the three contacts in sequence. Triangle connection has two kinds of connection methods: forward connection and backward connection. When drawing the wiring diagram, the three-phase windings should be vertically arranged in parallel, with the phase sequence from left to right, and the first end of the previous phase winding is connected with the end of the next phase winding in sequence. Instead, the end of the previous phase winding is connected with the head of the next phase winding in sequence. When drawing the phasor diagram, the B phase is still drawn vertically upwards, and the three-phase contacts are arranged clockwise in sequence to form a closed equilateral triangle. The delts point to the right when connected in sequence, the delta points to the left when connected in reverse, and the potential and voltage direction of each phase are the same as those of the wye connection.

That is, the phasor diagram is drawn according to the connection of three-phase windings, which is a configuration diagram. The equipotential points coincide as one point on the diagram, and the directed line segment between any two points represents the phasor of the potential between two sides and three knife points and the directions point from the end to the head.

When connecting the three-phase winding, it must be carried out in strict accordance with the winding end sign and wiring diagram, and the head and end of the one-phase winding must not be interchanged, otherwise, the three-phase voltage will be asymmetrical, and the three-phase current will be unbalanced, and even the transformer will be damaged.

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Delta–delta transformers

Delta-delta transformers are mainly three-phase transformers, but a small part of them are used for single-phase transformers. Three-phase loads are usually motors, transformers, and other loads, while single-phase loads are usually lighting and low-voltage power supply. The single-phase load is fed by grounding the center tap on a branch of the secondary coil of the delta transformer and then connecting the single-phase load between a phase on the grounding branch and the grounded neutral line.

If one single-phase transformer in delta-delta transformer fails and cannot operate, the transformer can only operate with two transformers to form an open delta configuration. At this time, although the kVA rating of the transformer decreases, it still provides three-phase power to the load.

Wye–wye transformers

Wye-wye transformers can be used for single-phase and three-phase loads. Wye–The third harmonic current and voltage generated Wye-wye transformers will interfere with the nearby communication circuit or cause various power quality problems.

Delta–wye transformers

Delta–Wye Transformers are the most common three-phase transformers. If one single-phase transformer in Delta–Wye Transformers fails, the whole transformer group will not be able to continue its normal operation and work.

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Advantages of delta-delta transformers

1. the delta-delta connection has advantages in balanced and unbalanced loads;

2. If the third harmonic appears in the IF circuit, it will circulate in the closed loop of the delta, so it will not appear in the output voltage.

Disadvantages of delta - delta Transformers

The main disadvantage of this type of transformer is the lack of available wye-point or neutral terminal. Therefore, when the wye-point or neutral terminal is not needed and the voltage is low, the delta-delta transformer can be used.

What is an open delta transformer?

In a three-phase system, the transformer usually has three windings on each side, thus forming a triangular or star connection. This is a common transformer configuration. Open delta transformer is a special type of transformer which has only two windings but can still convert three-phase voltage. Generally, when one winding of the transformer fails, the Open delta transformer will be used for emergency response, or the Open delta transformer will be used for low load. Therefore, open delta transformer is not commonly used.

Daelim  Transformer is a high-voltage transformer manufacturer, which can produce transformers of various international standards such as IEEE/ANSI/DOE/CSA/AS/UL. Daelim has more than 20 years of history and experience in producing and selling transformers overseas, with strong strength and rich experience in producing and exporting transformers. Finally, Daelim provides high-quality after-sales and repair services, and overseas customers can solve the problem of repairing transformers locally.

Contact Daelim for transformer sales records. Therefore, if you are looking for a new transformer supplier at this time, Daelim will be your good choice.