What standards are implemented for transformer windings

Power transformers.

Technical parameters and requirements of oil-immersed power transformers.

GB7251-87 Guidelines for Analysis and Judgment of Dissolved Gas in Transformer Oil GBJ148-90 Code for Construction and Acceptance of Power Transformers, Oil-immersed Reactors and Transformers in Electrical Installation Engineering.

GB7665-87 transformer oil.

DL T572-95 Power transformer operating regulations.

DL T574-95 Guidelines for the operation and maintenance of on-load tap-changers.

Power transformers.

Technical parameters and requirements of oil-immersed power transformers.

GB7251-87 Guidelines for Analysis and Judgment of Dissolved Gases in Transformer Oil GBJ148-90 Code for Construction and Acceptance of Power Transformers, Oil-immersed Reactors and Transformers in Electrical Installation Engineering.

GB7665-87 transformer oil.

DL T572-95 Power transformer operating regulations.

DL T574-95 Guidelines for the operation and maintenance of on-load tap-changers.

The winding of the transformer is the meaning of the coil.

A winding has two wire heads, which can be made by indirect wire ends in the winding, and the one connected to the center of the winding is called the center tap, and a winding is composed of one or more coils. The windings of a low-frequency transformer are called primary windings and secondary windings, which have a primary winding and one or more secondary windings, which can be sold to obtain different voltage ratios or impedance ratios. The windings of the low-frequency transformer are all wound with copper enameled wire.

The windings of high-frequency transformers are called primary windings, secondary windings, feedback windings and codes, which are the same as low-frequency transformers in that there can be several secondary windings, and the difference is that some high-frequency transformers need to have feedback windings. High-frequency transformers mostly use copper enameled wire, because the high-frequency current has a skin effect, in order to reduce costs, there are also copper-clad aluminum enameled wires.

Hello! Several concepts of transformers are explained below, I don't know if they can help you understand!

1. Single-phase transformer: it is connected to 220 volts or 380V line voltage and phase voltage, and the input and output of the two windings are single-phase, which is a single-phase transformer, 2. Three-phase transformer: that is, the input of three live wires is 6kv, 10kV voltage level, and the output terminal is also a three-phase voltage of 400V, the neutral wire and the live wire are 220 volts, and the live wire and the live wire are 380 volts.

3. Primary and secondary winding: that is, the input voltage winding is the primary winding, and the output winding is the secondary winding.

4. High-voltage and low-voltage winding: that is, the input high-voltage winding is the high-voltage winding, and the output low-voltage winding is the low-voltage winding.

5. A, B, C phase winding, is a three-phase transformer, there are three windings in the transformer core, divided into phase A, phase B, phase C, that is, the output voltage of 400 volts, usually we say 380 voltage, for three-phase loads, such as three-phase motors; The neutral line and phase A, B, and C are 220 volts, which are used in our homes, schools and other places, such as lighting, refrigerators, washing machines, air conditioners, televisions and other electrical appliances.

Transformer windings can be divided into two types: co-core and overlapping according to the arrangement of the primary and secondary windings on the core (Figure 3-4).

Figure 3-4 transformer winding structure.

a) Coax winding (b) Overlapping winding.

The co-core winding is to wind the primary and secondary windings into cylindrical coils of different diameters and put them on the core column. There is a certain insulation gap between the high-voltage winding and the low-voltage winding, and they are separated from each other by insulating paper tubes. The co-core winding can be divided into cylindrical type, continuous type, spiral type and tangled type.

Generally, the high-voltage winding is on the outside and the low-voltage winding is on the inside. This kind of winding structure is simple and easy to wind, so it is widely used.

The overlapping winding is to set the primary and secondary windings on the core column in a certain alternating order, this kind of winding is very inconvenient to wrap because of the gap between the high and low voltage windings and the complex insulation, but it has the advantage of high mechanical strength, and is generally used in large shell transformers (such as large-capacity electric furnace transformers and electric welding machine transformers).

The first type of layer type: only one type of cylindrical type, which can be subdivided into single-layer, double-layer, multi-layer and segmented cylindrical type.

The second type of cake type: spiral type, which includes single helix, double helix, triple helix, single half helix, double half helix, four helix, four half helix, etc.

Continuous: single continuous, double continuous, tangled, inner screen type, there are a variety of ways to insert capacitors across two sections, across four sections, etc., and there are a variety of tangled methods such as ordinary entanglement and flower arrangement.

Objective: The transformer with a conversion ratio of k is equivalent to a transformer with a transformation ratio of 1, so that the two separate circuits of primary and secondary can be drawn together.

Principle: Keep the electromagnetic action generated by the secondary winding before and after conversion unchanged, that is, keep the electromagnetic relationship inside the transformer unchanged. Specifically, the magnetokinetic potential, active loss, reactive loss, apparent power and the main magnetic flux of the transformer generated by the secondary winding remain unchanged.

Basic rules of conversion:

The converted value of each sub-side quantity belonging to electric potential and voltage is equal to its original value multiplied by the transformation ratio;

The converted value of the secondary side quantities belonging to the impedance class is equal to the square of the original value multiplied by the transformation ratio;

The converted value of the secondary current is equal to the original value divided by the conversion ratio.

How to convert the parameters of the primary side of the transformer to the secondary side?

The transformer is a static electromagnetic device, the primary winding and the secondary winding are connected by an alternating magnetic field, and the electromagnetic induction relationship is used to realize the electrical energy conversion. According to the actual distribution and function of the magnetic field inside the transformer, the magnetic field is divided into the main magnetic flux.

and leakage flux. The main magnetic flux is closed along the iron core, which acts as a medium for energy transfer, and the magnetic circuit through which it passes is nonlinear. The flux leakage is mainly closed along the non-ferromagnetic material and only reacts.

The effect of the voltage drop chain signal, the magnetic circuit is linear.

In transformers, there are both problems with the magnetic circuit and problems with the circuit. In order to put the electromagnetic field.

The problem is transformed into a circuit problem, and the circuit parameters are introduced: excitation impedance zm, leakage reactance x1 x2. zm=rm +jxm 。

The excitation resistor RM is not an actual resistor, it is just a resistor that represents the iron consumption, and the power dissipated on it is equal to the iron consumption. The excitation reactance xm corresponds to the main flux m, and x1 and x2 correspond to the leakage flux 1 and 2 of the primary and secondary windings, respectively, and they are proportional to the frequency of the power supply, the square of the number of turns, and the permeability of the magnetic circuit through which the corresponding flux passes.

where f is the frequency of the power supply; n1 – the number of turns of the primary winding;

the magnetic permeability of the magnetic circuit through which m passes; n2 - the number of turns of the secondary winding;

1. The magnetic permeability of the magnetic circuit;

2. The magnetic permeability of the magnetic circuit;

Since m is closed by the core, it is affected by the saturation of the core.

It is not a constant, and as the saturation of the core increases, it becomes smaller. 1 and 2 are mainly closed by non-ferromagnetic materials and are basically not affected by the saturation of the core.

It's basically constant. In addition, due to.

Therefore. In order to simplify the quantitative calculation and obtain the equivalent circuit of the connection between the primary and secondary measurement of the transformer, the folding algorithm is introduced. The conversion method is to replace the secondary winding with a winding with the same number of turns as the primary winding.

The principle of conversion is to keep the magnitude and spatial distribution of the magnetodynamic potential of the secondary winding unchanged before and after conversion, so as to make various physical quantities of the primary winding.

Remains the same before and after conversion.

The main flux m is induced by the electromotive force in the primary and secondary windings.

The size of the

e1 = e2 = in phase, both lag behind 90°.

The variable ratio k is defined as the ratio of e1 and e2. k can be calculated in several ways. It is calculated as:

where U1N, U2N - the rated phase voltages of the primary and secondary windings of the three-phase transformer. For single-phase transformers, k=u1n u2n.

When the core is saturated, the excitation current is used to obtain the magnetic flux of the sinusoidal change.

It must be non-sinusoidal. In addition to the fundamental wave, the excitation current mainly contains the third harmonic component. When there is no load, the main magnetic flux of the transformer is established by the no-load current, therefore, the no-load current is the excitation current. When loaded, the main flux is built up with primary and secondary Sakura-style windings.

Basic equations.

Equivalent circuits and phasor diagrams are the three ways to analyze transformer problems, and the three are completely identical, and knowing one of them can lead to the deduction of the other two. In practice, it can be flexibly used according to specific situations.

The most important parameter of a transformer is the percentage of short-circuit voltage, i.e. uk. According to the "Power System Analysis", knowing the uk, rated capacity and rated voltage of the transformer, the total reactance of the transformer's high and low voltage windings can be calculated.

The named values for the impedance of the high and low voltage windings are: z = uk% *un 2 sn;

In simulink, we need to fill in the following:

In other words, you need to fill in the nominal values of resistance and inductance (reactance) of the windings on the high-voltage side and the low-voltage side.

We are mainly concerned about the writing of reactance, dividing the uk% by 2, which is the reactance parameter in Simulink. For example, if a transformer has a short-circuit voltage percentage of 6%, then write 3% for both L1 and L2 in Simulink.

Note: The standard unit value of the reactance is the same as the standard unit value of the inductor.

In BPA, the transformer parameters that are generally required to be filled in are based on the standard unit value of the base capacity of 1000MVA and the rated voltage of 220kV (here it can be changed to other voltage levels), which involves the calculation of the unit value between multiple voltage levels.

Here's what I think makes a good calculation:

The famous bending value is calculated first, converted to 220kV, and then the unit value below this voltage level is calculated. Here's an example:

The rated voltage of the transformer, the rated capacity is 1MVA, UK%=. Then calculate the standard unit value at a reference power of 1000mVA and a reference voltage of 220kV.

Calculate the named value at 35kv first.

uk%*35^2/1

It is then reduced to 220kV.

uk%*35^2/1 *(220/35)^2

Finally, the unit value at 220kV is calculated.

uk%*35^2/1*(220/35)^2/（220^2/1000）=uk%/1*1000

That is to say, when the transformer is converted between different voltage levels, without considering the non-standard transformation ratio of the transformer, as long as the short-circuit impedance, rated capacity and reference capacity of the transformer are known, the vertical standard value of the transformer under the reference voltage can be calculated by the following formula:

uk% transformer rated capacity * base capacity.

The winding is the main part of the variable tracking register, and the winding can be divided into primary winding and secondary winding. The primary winding is a resistor connected to the power supply and is able to receive a trace of energy from the power supply; The secondary winding is the winding connected to the load, which mainly provides energy to the load.

The primary side pin and the secondary side pin of the power transformer are generally led out from both ends, and the primary winding of Zizhou is marked with 220V, and the rated resistance value is generally marked on the secondary winding, such as 15, 24, 35V, etc., which can be judged according to the marked words. Usually we also see some words that are not very clear, so at this time we can judge according to the thickness of the winding wire diameter and the number of turns, for example, the diameter of the primary winding is thinner, the number of turns is also more, the more turns, the greater the resistance of the winding. The secondary winding is just the opposite; It can be seen that the resistance of the primary winding is much larger than that of the secondary winding.

Based on this characteristic, we can also use the resistance level of the multimeter to measure the individual resistance values of the transformer to determine which winding.

Several common transformer winding methods:

Dense winding. Dense winding is the close relationship between the lines and the lines, and the middle line can not be layered and crossed in the winding, for example: the second layer is not allowed to appear when the first layer is tightly wound, and the gap and intersection between the lines are not allowed. Mo Tan Zai.

1. The line is evenly and tight;

Even-winded. Even-winding means that the distance between the lines is roughly equal, wrapping the entire winding area, and the starting and winding lines should be close to the end control tape, but the upper end control tape is not allowed.

1. The winding fills the entire winding area;

2. The distance between the lines is roughly equal;

3. The starting and winding lines are wound by end-control tape, and there is no upper end-control.

And wrap around. Two or more wires are wound in parallel with the same set of wires, each of which is parallel, cannot be crossed, the take-up line cannot be hung in the wrong position, and the incoming and outgoing wires should be at right angles.

This winding method can be roughly divided into four situations:

1. Winding in the same group;

2. Different groups are wound together;

3. Multiple groups are wound together;

4. Different groups or the same group double winding.

Winding on the same layer. 1. The same layer winding is that two or more windings are wound on the same layer, and the starting and winding wires between each winding are independent insulation;

2. The winding should be uniform, the line should not climb on the end control tape when the wire is tightly wound, the incoming and outgoing lines should be at right angles, and the specific requirements of the letter mold should meet the requirements of the work instructions.

2. The winding should be uniform, and the incoming and outgoing lines should be at right angles, and the specific requirements of the work instructions should be centered and densely wound or centered.