What is the best size to choose for civilian transformers?

When choosing a civilian transformer, the appropriate capacity depends on the specific usage scenario and requirements. ‌

For household appliance transformers, the general recommendation is to choose a transformer that can carry 80% of the rated power of the equipment. This is because inductive loads (such as motors) have a large instantaneous current when starting, so using 70% of the rated power is sufficient. If it is only used for a short period of time, even smaller power can be selected. For example, choosing a 220/110V transformer with a power range of 50-60W can meet the needs of most households, while also providing appropriate power surplus. ‌

For larger civil buildings or residential areas, the selection of transformers needs to consider the reliability of power supply, initial investment costs, and operational economics. When considering transformer capacity, it should be calculated and determined based on actual load. For example, for the calculation of electricity load in residential buildings, the unit index method needs to be combined with coefficients for calculation. For example, a coefficient of 0.6 can be applied to 30 households per unit, a coefficient of 0.5 can be applied to 60 households per building, and a coefficient of 0.4 can be selected for transformers in 240 households. In addition, as mentioned in typical examples, for the case of 900 households, using a three-phase distribution coefficient of 0.26 and a power consumption of 6kW per household, it is appropriate to calculate the transformer capacity with a load of 1404kW. ‌

In summary, when choosing a civilian transformer, the appropriate transformer capacity should be determined based on specific usage scenarios and requirements. For household use, a transformer of 50-60W can be selected; For larger residential areas or civil buildings, it is necessary to calculate the specific electricity load and select the appropriate transformer capacity to ensure the reliability, economy, and environmental friendliness of power supply.

What Is A Transformer?

Power supply design is an unavoidable issue in current hardware product design. In the previous article, we have discussed several types of DCDC converters. Today, we will explore another low loss buck boost scheme: transformers.

A transformer is an electromagnetic component of a circuit used to change the alternating voltage. It can convert one AC voltage into another through electromagnetic conversion while keeping the power basically unchanged.

Application of Transformers

In the power system, transformers are widely used for increasing or decreasing voltage. It can be used for electrical isolation, significantly improving system safety and reducing the risk of electric shock; The use of transformers also achieves grounding system separation, which can effectively suppress common mode noise; Provided DC isolation to protect sensitive circuits; Simultaneously achieving voltage conversion and impedance matching while isolating; Restricting the scope of fault propagation and improving system reliability; Improved electromagnetic compatibility, helping to meet EMC requirements; Support multiple winding applications and adapt to complex system requirements; It can also be used for special applications such as signal coupling, phase adjustment, and harmonic suppression. These advantages make transformers an indispensable key component in fields such as power, industry, healthcare, and communication, providing solid guarantees for the safety, efficiency, and reliability of modern electrical systems and greatly promoting the development of modern power systems.

Working Principle of Transformer

The working principle of transformers is based on the law of electromagnetic induction. Its electromagnetic structure consists of two or more coils wound around the same iron core. In practical structures, there will be insulation materials used between windings and between windings and iron cores, as well as between the casing and cooling system.

When AC current passes through the primary coil, an alternating magnetic field is generated in the iron core. This alternating magnetic field will induce voltage in the secondary coil. By adjusting the turns ratio of the primary and secondary coils, different output voltages can be obtained. Usually, transformers have more than one circuit, for example, single-phase transformers have two circuits, while three-phase transformers have six circuits.

The iron cores and winding materials of different transformers vary greatly. Julin Technology's PowerExpert supports simple and flexible custom transformer construction. Custom transformers can be built using winding, core or non-linear core, and winding binding (K_Magnatic) devices. The ideal magnetic core supports setting magnetic permeability, cross-sectional area and length, while the nonlinear magnetic core supports setting shape parameters, magnetic domain wall bending constant, hysteresis loss coefficient, saturation magnetization intensity and other coefficients. The magnetic core and winding are set to belong to the same transformer through winding binding devices.

Build a simple custom transformer using PowerExpert software, where the winding has 5 turns and 10 turns, as shown in the following figure:

Perform transient simulation, and the simulation results obtained are shown in the following figure:

Bobbin dyeing technology: subjective reasons cause of non-recurrence of yarn through cone yarn dyeing are roughly as below:  winding quality, dye selection, dyeing process, operating factors, management problems, etc.

WINDING QUALITY INFLUENCES REPRODUCIBILITY

(1) Bobbin weight: When dyeing by immersion method, the depth of apparent color depends largely on the weight ratio of dye to yarn. In generally, only the number of bobbin is counted when the yarn is put on the cone yarn carrier, no longer weighed again. Therefore, the winding weight determines weight of loading yarn, be weighted after soft winding. Many factory production practices have proved that even without a fixed length meter, it is completely possible to weigh each bobbin and control the weight within the range of ± 1%. Some dyeing plants use "card" to measure the outside diameter, but because of the large error, it is not suitable. The different size of package yarn after dyeing also will get color difference betweent bobbin yarn.

(2) Bobbin winding density: The winding density of soft bobbin with direct relationship to resistance of circulation of dyeing liquor . High density, high resistance. Resistance magnitude affects shape of dyeing liquor circulation resistance curve, then affects main circulation pump, affects the circulation flow of the dye fluid, the circulation frequency of dye fluid and number of cycles within specified time are changed, so the amount of dye on yarn is changed, causing the color of yarn to be deep or shallow.

When some bobbin winding density is too small, sometimes the yarn will be out of the "groove", sometimes caused "collapse", the dye liquid will get "short circuit", not only the yarn is washed and dyed unevenly, but also rest bobbin dye liquid circulation will be reduced and cause light color.

(3)"Hole exposure" : Because the bobbin and the beam coil are full of holes for the dye to travel through, when the bobbin is not properly wound, or the reciprocating distance is not enough, "hole exposure" will occur. When dyeing, because the warp shaft is placed vertically in the main body of high pressure cone yarn dyeing machine, if winding is too loose, the yarn will fall due to gravity after wetting at sometimes, resulting in upper "hole exposure". The dye liquor will "short circuit" from the "exposed hole", not only wash the yarn on the end of the bobbin, but also affect the flow capacity of other bobbin.

PRETREATMENT INFLUENCES REPRODUCIBILITY

Many dyeing plants don't pay attention to pre-treatment. Actually, many problems in dyeing processing because of ingnoring do enough pre-treatment. Impurity removal degree, whiteness, pH value after washing, purification of hydrogen peroxide after bleaching, amount of alkali carried by mercerized yarn, different tension affect gloss. When dyeing bobbin yarn, pre-treatment, dyeing and post-treatment are carried out in the same high pressure bobbin dyeing machine, and the pre-treatment effect is also different.

Generally, the dyeing factory pays more attention to force determination and weighing of dyes，but less attention is paid to the force determination and weighing of other chemicals. 

Caustic soda, soda ash, hydrogen peroxide is not analyzed, only calculated according to instructions, dye liquor are rarely titrated. So pre-treatment effect is different, causes difference of color depth and hue.

As mentioned, paying attention to compatibility, compatibility, sensitivity and quality of dyestuff, in order to ensure reproducibility.

RATIONALITY OF DYEING TECHNOLOGY INFLUENCES REPRODUCIBILITY

Although selecting appropriate dye, the dyeing process is designed not reasonable, there also be cylinder differences.  Such as temperature design, heating rate, holding time, amount of additives and feeding method scientificity, the rationality of post-treatment process design will affect the dyeing amount of dyestuff resulting in color difference.

Such as adding reactive dye solid alkali, fixation and hydrolysis of reactive dyes have a lot to do with the pH value of dye bath, the scientific feeding method is to maintain the Pu value at a fixed value (such as pH value is 11.5), which is related to the feeding method and feeding rate, if one-time feeding or feeding fast and slow all will cause pH fluctuations, amount of fixation and hydrolyzed dyes is different, finally eflects the different shades of light.

In order to fully improve the added value of colored product, except add patten, high-count yarn & blended yarn and special dyeing process can also be used to achieve a unique style of colored cloth. Pure cotton blended yarn-dyed fabric: soft feel, breathable, strong water absorption. In recent years, it has been favored by the majority of consumers. Color cotton by mixing cotton, carding cotton, spinning, weaving to eliminate color difference, it is convenient production.

RAW MATERIAL REQUIREMENT

1. Raw cotton requirement

After the raw cotton dyeing, the color cotton should be mixed, combed, spun, and finally wovenhttps://www.yarnfabricdyemachine.comknitted, and the requiements of color difference is not strictly, so it is suitable for any variety of raw cotton.

2. Dye compound

The dyestuffs and auxiliaries are used for cotton bleaching and dyeing: with fine particles and soluble in water, good diffusion and permeability.

DYEING

In order to obtain better color mixing effect of cotton textiles, pay attention to two important points in raw cotton dyeing: remove natural impurities of loose fiber and spinnability of dyed cotton fiber.

1. Pretreatment

Cotton fibers contain many symbionts, such as waxes, nitrogen, pectin, minerals and natural pigments, cottonseed shells, etc. The existence of these symbionts will seriously affect the wettability of cotton fiber, making it difficult to dyeing, so it must be removed first. The pre-treatment of raw cotton dyeing: boiling and bleaching and related washing. The purpose is to remove cotton impurities, fruit gum and natural pigments that hinder dyeing. After boiling and fully washing, it is necessary to check whether the concentration of alkali, residual hydrogen peroxide and whiteness meet the process requirements or not. Generally, the whiteness of the cotton fiber after pre-treatment are consistent, and the pH value is neutral.

2. Raw cotton dyeing

Using direct dyes and reactive dyes, considering the color fastness and convenience of use, using reactive dyes is better, because reactive dyes with bright color, complete chromatography and a certain wet processing fastness. The process control is stable and appropriate additives, the reproducibility of dyeing is good, cylinder (batch) difference is less. In addition, the use of reactive dyes dyeing, if it is combination of color, it is best to choose a better compatibility of reactive dyes for collocation.

3.  Postprocessing

Post-treatment is an important part of raw cotton dyeing, after dyeing should do fully washed and soaping treatment, in order to remove impurities and residual chemical additives on the cotton fiber. When washing, detergent with strong decontamination ability and good permeability should be used to enhance the cleaning effect of the inner layer of the fiber. After washing, in order to increase the spinnability, softening agent should be added for softening treatment to improve the lubricity of the fiber.

DEHYDRATOR AND DRYING

After dehydration , the color cotton treated by softener is easy to loose, after production practice, the moisture return after drying is controlled at 6 to 8, with soft feel and good spinnability.

SPINNING TECHNOLOGY

After raw cotton dyeing, the cotton fiber lost  spinnability processing of boiled and bleached, removed wax and oil, feel becomes coarse. In order to improve this situation, one the one hand, adding softener to loosen the cotton and improve its spinnability after full washing. On the other hand, reasonable cotton matching with raw cotton. There are two kinds of cotton matching between colored cotton and raw cotton: One is carried out in the cotton cleaning process, the color cotton and the raw cotton after grabbing cotton, mixing cotton, opening into rolls and  strips, finally spinning and knitted or woven fabric; Another one is processing during combining, the color sliver with the raw cotton sliver, through two strips, so that it is mixed into a strip, finally spinning and weaving or knitting. Through experiment, the former method is better, color cotton and raw cotton through mixing , carding, spinning and weaving, basically eliminate color difference.No matter which one is adopted, the mixing ratio of color cotton and raw cotton is generally controlled at about 0.5-10 percent, spinnability is better, don't  change the original production technology.

DYEING INTANCE

9.7tex red cotton using Shin Tong Yunn high pressure dyeing machine, bath ratio 1:15, internal and external cycle time ratio 5:3.

1. Process flow: raw cotton- boiling-washing-dyeing-washing-soft treatment-dehydration-drying - packing

2. pretreatment

Process prescription, (ghttps://www.yarnfabricdyemachine.comL)NaOH(36 'Be) 5 stabilizer FT 2OH202(27.5%) 8,  Temperature 120℃ penetrant JFc 1.0 time 120min.

3. Raw cotton dyeing (bright red) process prescription, (ghttps://www.yarnfabricdyemachine.comL) Peregal O 015 reactive brilliant orange X-Gn 3. 575N a2CO 3 25 Bright Red X一3B 6．i25Na2SO． 70。

4. Soft treatment

Process prescription, (ghttps://www.yarnfabricdyemachine.comL) softener HC-8

5. Dyeing cotton by spinning process

Cotton blending - roll - carding - strip - roving - fine yarn - raw cotton - fine cotton

NOTE:

DF241 series high pressure cone yarn dyeing machine is suitable doing pre-treatment, post processing and dyeing of raw cotton(cotton fiber), only need change the carrier form.