Energy Efficiency Standards for Transformers in Various Countries

Energy Efficiency Standards for Transformers

As a large energy consumer in the power transmission and transformation industry, the energy saving potential of the transformer industry is huge. Improving the energy efficiency of transformer is an important part of power conservation and emission reduction.

In order to reduce the loss of power transformers, many countries have issued transformer energy efficiency standards and policies, such as GB20052-2006 and GB24790-2009 issued by China, the United States launched the “Energy Efficiency Star Transformer Program” in 1998, and the European Union in 2005. Transformer Promotion Partner Program”, Japan began to implement “Transformer Energy Efficiency Leader Program” in 2006. China’s current transformer energy efficiency standards are GB20052-2013 and GB24790-2009.

China’s transformer energy efficiency standards limit the no-load loss and load loss of transformer products, and set the threshold for transformers to enter the market (level 3 energy efficiency indicators) and the index requirements for obtaining energy-saving certification (level 1 and 2 energy efficiency indicators).

Daelim’s transformers fully comply with the standards of various countries and have passed CSA, IEEE, IEC, ANSI and other certifications to ensure that the transformers you buy have quality assurance. Help you quickly improve energy efficiency and save money.

At the same time, Daelim also provides you with up to two-year warranty to ensure your safety.

Table of Contents

Energy Efficiency Transformer Index

In the energy efficiency transformer standards of various countries, the energy efficiency indicators of transformers are different. China’s energy efficiency standard GB20052-2013 uses no-load loss and load loss, and Japan’s leader plan transformer energy efficiency standard uses total loss under a certain load rate.

The United States uses the efficiency of the transformer at a certain load rate. Although the energy efficiency indicators are different, the no-load loss and load loss of Chinese transformers can be converted to the total loss of Japanese standards and the efficiency of the United States for comparison.

China’s transformer energy efficiency testing standards are GB/T1094.1-2013 and GB/T1094.11-2007.

Japanese transformer energy efficiency testing standards are JIS C4304-2013 and JIS C4306-2013.

The American transformer energy efficiency testing standard is NEMA TP2-2005 developed by the Electrical Manufacturers Association. See Table 1 for transformer energy efficiency indicators and testing standards.

Transformer energy efficiency indicators and testing standards

Japan Transformer Energy Efficiency Standard

Japan Transformer Energy Efficiency Standard

JIS C4304-2005 “6k V Oil-immersed Distribution Transformer” and JIS C4306-2005 “6k V Sealed Winding Distribution Transformer” are both Japanese energy efficiency standards for distribution transformers.

The standard specifies the total losses of distribution transformers at a certain load factor (40% or 50%). The formula for calculating the total loss is:

Total loss=no-load loss+(m/100)2×load loss,

In formula W, m is the standard load rate, 40% for rated capacity 500k VA and below, and 50% for rated capacity above 500k VA.

The load loss is the load loss (W) at the rated capacity at the reference temperature.

The reference temperature of oil-immersed transformer is 75℃;

The reference temperature of the sealed winding type (dry type) transformer is 95°C (Class B); 115°C (Class F); 140°C (Class H).

The temperature coefficient is 235 for copper; 225 for aluminum.

The total loss limits of three-phase distribution transformers in Japan are shown in Table 2

In 2011, Japan released the second edition of the transformer leader target value, with a target year of 2014. The target value of the total loss of the distribution transformer shall comply with the following calculated values, see Table 3.

Japan 2011 2nd Edition Front Runner Distribution Transformer Target Value

In 2013, Japan released the industrial standards JIS C4304-2013 and JIS C4306-2013, which replaced the front runner standard target values in JIS C4304-2005 and JIS C4306-2005.

The new standard specifies the total loss limit of 6kV class single-phase 50Hz and 60Hz, 10kVA ~ 500kVA distribution transformers and 6kV class three-phase 50Hz and 60Hz, 20kVA ~ 2000kVA distribution transformers.

2014 is the compliance year of the new version of the energy efficiency leader standard for distribution transformers. The total loss of oil-immersed distribution transformers shall not exceed the limit of JIS C4304-2013, and the total loss of sealed winding (dry-type) distribution transformers shall not exceed JISC4306-2013 Limit, the allowable deviation is +10%.

The total loss limit of the new standard is basically the same as the target value calculated by the second edition of the frontrunner standard formula. The total loss limits of some three-phase distribution transformers are shown in Table 5

Japanese standard three-phase distribution transformer total loss (2013 version)

U.S. Transformer Energy Efficiency Standards

The United States started early in formulating energy-saving standards for energy-consuming products.

In 1996, the American Electrical Manufacturers Association (NEMA) issued the energy efficiency standard for distribution transformers NEMA TP1-1996 “Guidelines for the determination of energy efficiency of distribution transformers”.

In 1998, NEMA released the test method standard for energy consumption of transformers NEMA TP2-1998 “Standard Test Method for Measuring Energy Consumption of Distribution Transformers”.

The U.S. Department of Energy and the Environmental Protection Agency jointly launched the ENERGY STAR Transformer Program in 1998 to promote high-efficiency, low-loss distribution transformers.

In 2002, the American Electrical Manufacturers Association released NE-MA TP1-2002. Later NEMA TP1-2005 was released. Suitable for oil-immersed, dry-type, single-phase and three-phase distribution transformers with a primary voltage of 34.5kV and below.

NEMA TP1-2002 expresses the energy efficiency level of a transformer by its efficiency at a certain temperature and a certain load rate. The formula for calculating transformer efficiency in the standard is:

E=(100×(P×k VA×1 000))/P×k VA×1 000+NL+LL×P2×T

In the formula, P is the load factor, which is 0.5 for oil-immersed and medium-voltage dry-type distribution transformers, and 0.35 for low-voltage dry-type distribution transformers;

kVA is rated capacity (kVA); NL is no-load loss (W);

LL is the load loss (W) under rated load;

T is the load loss temperature calibration coefficient,

Specify the reference temperature (55°C for oil-immersed transformers and 75°C for dry-type transformers).

Temperature coefficients: 234.5 for copper and 224.5 for aluminum.

The standard specifies the efficiency values of single-phase oil-immersed 10k VA ~ 833k VA distribution transformers and three-phase oil-immersed 15k VA ~ 2 500k VA distribution transformers;

The efficiency values of single-phase dry-type 15k VA ~ 333k VA low-voltage (600V) distribution transformers and three-phase dry-type 15k VA ~ 1 000k VA low-voltage (600V) distribution transformers are specified;

Efficiency values of single-phase dry-type 15kVA~833kVA medium-voltage distribution transformers and three-phase dry-type 15kVA~2 500kVA medium-voltage distribution transformers.

In 2007, the U.S. Department of Energy issued the energy-saving standard for distribution transformers with the document number EERE-2010-BT-STD-0048. The standard was implemented on January 1, 2010, and the scope of application includes oil-immersed and dry-type, single-phase and three-phase distribution transformers.

The standard specifies the efficiency value of three-phase oil-immersed distribution transformers from 15k VA to 2 500k VA, which is the federal energy-saving standard for oil-immersed distribution transformers implemented from January 2010 to January 2016.

Higher efficiency values for three-phase oil-immersed distribution transformers are also specified in the standard, which will be implemented in January 2016.

On April 18, 2013, the U.S. Department of Energy issued DOE 201610 CFR Part 431 part ii, which is a distribution transformer energy efficiency standard (DOE standard) implemented in January 2016. It uses the minimum efficiency of a certain load rate to represent the transformer energy efficiency. is a mandatory standard.

Oil-immersed distribution transformers are basically the same as the efficiency values implemented in January 2016 in EERE-2010-BT-STD-0048. Some efficiency values are shown in Tables 6 and 7.

Three-phase oil-immersed transformer efficiency

Three-phase dry-type low-voltage transformer efficiency in the United States

Scope of application

China Transformer Energy Efficiency Standard GB20052-2013 is applicable to three-phase 10kV, non-excitation voltage regulation, oil-immersed distribution transformers with a capacity of 30kVA to 1600kVA and dry-type distribution transformers with a capacity of 30kVA to 2500kVA.


Japanese energy efficiency standards apply to 6k V class single-phase 50Hz and 60Hz, 10k VA to 500k VA, oil-immersed and dry-type distribution transformers, 6k V class three-phase 50Hz and 60Hz, 20k VA to 2 000k VA, oil-immersed and Dry-type distribution transformers.

The US energy efficiency standards are applicable to voltage 34.5k V and below, single-phase oil-immersed 10k VA to 833k VA distribution transformers, three-phase oil-immersed 15k VA to 2 500k VA distribution transformers, and single-phase dry-type 15k VA to 833k VA Distribution transformers, three-phase dry-type 15k VA ~ 2 500k VA distribution transformers.

Reference temperature

The Chinese load loss reference temperature is related to the insulation class. Oil-immersed transformers are generally 75°C; dry-type transformers are 100°C (B-grade), 120°C (F-grade), and 145°C (H-grade).

Japanese standard load loss reference temperature: 75°C for oil-immersed transformers; 95°C (Class B), 115°C (Class F), and 140°C (Class H) for sealed winding (dry-type) transformers.

The US standard no-load loss reference temperature is 20°C, and the load loss reference temperature is: 55°C for oil-immersed transformers; 75°C for dry-type transformers.

Load rate

Chinese transformer load factor is rated load.

Japanese standard load factor: 40% for rated capacity 500k VA and below, 50% for rated capacity above 500k VA.

U.S. standard load factor: 50% for oil-immersed and medium-voltage dry-type distribution transformers, and 35% for low-voltage dry-type distribution transformers.

Total loss

The no-load loss and load loss in GB20052-2013 are brought into the total loss formula in the Japanese standard, and converted into the total loss in the Japanese standard for comparison.

The reference temperature for load loss of oil-immersed transformers in China and the reference temperature for load loss in Japan are both 75°C, and no temperature conversion is required.

The no-load loss value and the load loss value in the Chinese energy efficiency standard are brought into the formula to calculate the total loss. The comparison results of oil-immersed transformers are shown in Table 8.

The no-load and load losses corresponding to each level of energy efficiency of China’s oil-immersed transformers are converted into Japan’s total loss, and the total loss corresponding to level 3 energy efficiency is 9.37%~25.84% higher than Japan’s total loss.

The total loss corresponding to the level 2 energy efficiency of the partial capacity transformer is lower than the total loss in Japan, and the total loss corresponding to the level 2 energy efficiency of the partial capacity transformer is 2.08%~15.03% higher than the total loss in Japan.

The total losses corresponding to Level 1 energy efficiency are all lower than the total losses in Japan.

There is no deviation in China’s energy efficiency standards, and the allowable deviation in Japan’s energy efficiency is +10%.

After considering the deviation, the level 2 energy efficiency of China’s oil-immersed transformers can basically meet the total loss requirements of the Japanese energy efficiency standards.

Convert the load loss of China dry-type transformer class F (reference temperature 120°C) to the load loss of Japan class F (reference temperature 115°C).

The no-load and load losses are brought into the formula to calculate the total loss. The dry-type transformer class F comparison is shown in Table 9.

The no-load and load losses corresponding to each level of energy efficiency of China’s dry-type transformers are converted into Japan’s total loss, and the total loss corresponding to level 3 energy efficiency is 16.84%~36.21% higher than Japan’s total loss.

The total loss corresponding to level 2 energy efficiency is 5.85%~18.87% higher than the total loss in Japan.

The total loss corresponding to the Class 1 energy efficiency of some capacity transformers is 2.54% ~ 7.32% higher than the total loss in Japan.

There is no deviation in China’s energy efficiency standard, and the allowable deviation in Japan’s energy efficiency standard is +10%. After considering the deviation, the energy efficiency of China’s dry-type transformer class 1 can basically meet the total loss requirement of the Japanese energy efficiency standard.

China’s transformer energy efficiency level 3 is the basic level, which is quite different from Japan’s energy efficiency standards.

Efficiency value

Convert the no-load loss and load loss values in GB20052-2013 to the efficiency in the US standard. The no-load loss and load loss value (75℃) of oil-immersed transformer in GB20052-2013 are brought into the above formula, and the temperature calibration coefficient is used to convert it to the temperature specified by the American standard of 55℃, and the oil-immersed transformer GB 1, 2, Table 10 shows the corresponding efficiency values of the 3-level energy efficiency.

Transformer capacity in American Standard is: 15k VA, 30k VA, 45k VA, 75k VA, 112.5k VA, 150k VA, 225k VA, 300k VA, 500k VA, 750k VA, 1 000k VA, 1 500k VA, 2 000k VA, 2 500kVA;

Transformer capacities in China are: 30k VA, 50k VA, 63k VA, 80k VA, 100k VA, 125k VA, 160k VA, 200k VA, 250k VA, 315k VA, 400k VA, 500k VA, 630k VA, 800k VA, 1 000k VA , 1 250k VA, 1 600k VA.

Therefore, the efficiency values for some US capacities (50kVA, 100kVA, 315kVA, 1600kVA) in this paper are calculated by interpolation.

After conversion and comparison, the converted efficiency values of the oil-immersed transformers in the current energy efficiency standard GB20052-2013 are lower than the US standard efficiency values.

The efficiency value converted from the energy efficiency level 1 loss value of some capacity in China is higher than the US efficiency value, and some is lower than the US efficiency value.

China’s level 3 energy efficiency is the minimum required value for transformers in China, and there is a certain gap with the current efficiency value in the United States.

The no-load loss and load loss values of the dry-type transformer in GB20052-2013 (F-class reference temperature of 120 °C) are brought into the above formula, and the temperature calibration coefficient is converted to the American standard temperature of 75°C, and the dry-type transformer class F is obtained. Table 11 shows the corresponding efficiency values ​​of the national standard 1, 2 and 3 energy efficiency.

After conversion and comparison, the efficiency values of the dry-type transformers in China’s current energy efficiency standard GB20052-2013 after conversion of the energy efficiency loss value of class 3 are lower than the US standard efficiency value.

Some of the capacity efficiency values of China’s energy efficiency level 1 and 2 losses are higher than those of the United States, and some are lower than those of the United States.

China’s level 3 energy efficiency is the minimum required value for Chinese transformers, and there is a certain gap with the current efficiency value in the United States, and there is room for improvement.

Conclusion

After conversion and comparison, the total loss after conversion of the no-load loss and load loss limit of China’s oil-immersed transformer level 3 energy efficiency is higher than the Japanese standard total loss limit of 9.37%~25.84%.

The total loss after the conversion of the no-load loss and load loss limits of the level 3 energy efficiency of dry-type transformers in China is 16.84%~36.21% higher than the Japanese standard total loss limit. The total loss is 5.85%~18.87% higher than the Japanese total loss limit.

The no-load loss and load loss of the transformer are proportional to the total loss, and the total loss can be reduced by reducing the no-load loss or load loss. In the future revision of China’s transformer energy efficiency standards, it is recommended to consider reducing no-load loss and load loss.

After conversion and comparison, the converted efficiency values ​​of China’s oil-immersed transformers’ level 2 and 3 energy efficiency loss values ​​are lower than the US standard efficiency value, up to 0.29%. The efficiency values ​​of the dry-type transformers after conversion of the 3-level energy efficiency loss value are lower than the US standard efficiency value, up to 0.54%.

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