hybrid transformer
Hybrid Transformer
An all-in-one transformer integrating transformer and harmonic attenuation functions,
developed as the industry’s first solution through joint R&D with Korea’s five KEPCO generation subsidiaries and certified under the NET and Green Technology programs.
Growing Harmonic Damage
As nonlinear loads such as LEDs, inverters, and EV chargers increase, equipment damage caused by harmonics is expanding.
To prevent transformer failures, reduce losses, and improve efficiency, harmonic mitigation measures are essential.
Higher Transformer Losses and Rising Costs
Harmonics negatively affect electrical equipment by lowering efficiency and increasing temperature rise.
Harmonics do not merely raise electricity bills; they continuously increase the total cost of ownership (TCO) of electrical assets.
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Increased Energy Loss
Electricity charges rise in proportion to the added loss (△P) caused by harmonics.
- Annual additional cost = △P(kW) × 24h × 365 days × electricity unit price
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Transformer Derating
When harmonics are present, the effective usable capacity of a transformer can decrease by more than 20%.
- Example: Even if a 1,000 kVA transformer is installed, a severe harmonic environment may limit operation to around 800 kVA, reducing utilization efficiency by more than 20%.
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Shorter Expected Life
For insulation systems, expected life is reduced by about 50% for every 8–10°C increase in temperature.
- Temperature rise caused by harmonics can shorten replacement cycles from 25 years to 12.5 years or less, more than doubling long-term replacement cost.
Degraded Power Quality and Higher Losses
Harmonics are a major cause of poor power quality and rapidly increase electrical losses.
These losses stem from three main mechanisms inside the transformer.
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Eddy Current Loss, 𝑷𝑬𝑪
Harmonic currents sharply increase eddy current loss in proportion to the square of frequency.
- 𝑷𝑬𝑪 : Eddy current loss at rated frequency
- ℎ : Harmonic order(ℎ = 3, 5, 7, 9 ...)
- 𝐼ℎ : Harmonic current component of each order
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Stray Load Loss, 𝑷𝑶𝑺𝑳
Losses occurring in the transformer tank or structural members, increasing approximately with frequency to the power of 0.8.
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Ohmic Loss, 𝑷𝒅𝒄
Losses caused by increased effective conductor resistance due to the skin effect.
Examples of Harmonic Damage
Harmonics can cause many forms of damage in power systems and electrical equipment, including increased loss, overheating, noise, and malfunction.
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Capacitor failure -
Transformer failure -
Overcurrent / busbar damage -
MOF failure -
Motor overheating / burnout
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Transformer
Increased iron and copper losses,
overheating, increased noise,
reduced capacity,
insulation breakdown -
Rotating device
Overheating
reduced efficiency
shortened equipment lifespan
non-uniform torque,
vibrating torque -
Wires and conductors
Overheating,
Corona
Neutral overcurrent
Capacity reduction
Insulation breakdown
Skin Effect -
Power capacitor
Overheating,
excessive resonance
overcurrent
overvoltage insulation explosion -
Power converter
Sudden stop
inaccurate measurement,
generation of non-integer harmonics
malfunction
frequent component failure -
Circuit breakers, others
Reduced current capacity,
noise, vibration
accelerated lifespan degradation
drop in power factor
reduced fuse capacity
signal and communication failures
Tightening Harmonic Management Standards
The government is also strengthening harmonic management standards and mandates the use of transformers with harmonic attenuation functions in facilities that generate significant harmonics .
- Korean Agency for Technology and Standards, KS C 61000-3-6
- Ministry of Trade, Industry and Energy, Technical Standards for Electrical Installations and Korean Electrical Installation Regulations (KEC)
- Ministry of Land, Infrastructure and Transport, National Construction Standards Design Standards for Water Supply and Substation Facilities (KSD 31 60 10)
- Ministry of Land, Infrastructure and Transport, National Construction Standards Design Standards for Backup Power Supply Facilities (KSD 31 60 20)
- Korea Electric Power Corporation, Terms and Conditions of Electricity Supply (Article 39)
- LH Corporation, Specialized Specifications (Construction Standards) for Electrical Installations
- Korea Electrical Safety Corporation, Electrical Equipment Inspection and Check Standards (KESC)
- 113.8 Protection against harmonic currents (New)
- (Content) Electrical equipment must be protected against damage caused by harmonics due to the increase in non-linear loads.
- Laws and Regulations: Article 44 of the Construction Technology Promotion Act and Article 65 of the Enforcement Decree of the same Act
- Notice: October 11, 2019 (Ministry of Land, Infrastructure and Transport Notice No. 2019-549)
| Before revision | After revision |
|---|---|
| Transformers should be selected considering the location of use, economic feasibility, and electrical characteristics, but when installed inside a building, transformers with a standard energy efficiency or higher should be used. | When selecting a transformer, the location of use, load characteristics, efficiency, and safety must be considered, and a transformer with standard energy efficiency shall be used. However, for facilities with a high proportion of loads generating harmonics, a transformer with a harmonic attenuation function or a transformer with equivalent or superior performance may be used to improve power quality and reduce power loss. |
- The formula for calculating the capacity of emergency generators in buildings follows the KDS backup power supply standards.
- KDS backup power load facilities are required to apply harmonic weighting values when harmonic-generating loads, such as VVVF inverters or LED lamps, are included, and KDS backup power load facilities are required to apply harmonic weighting values when harmonic-generating loads, such as VVVF inverters or LED lamps, are included, and