バングラデシュでは、テキスタイルパークの運営マネージャーの公共料金が6か月連続で同じ問題を呈していました。パークの4台の1,000 kVAトランスは、数年間にわたり40%の平均負荷で稼働し続けた結果、コア損失が発生しました。これは、同じ周波数で発生する無負荷損失であり、不要で非生産的な電力使用に対して年間$18,000～$26,000のコストがかかることになります。エネルギー監査の結果、1990年代に遡る2台の配電トランスが、最新のモデルと同等の損失特性を持っていることが明らかになりました。実際のジレンマは、マネージャーが行動を起こす必要があるかどうかではなく、どのような行動を取るべきかということでした。マネージャーは、コンサルタントからエネルギー効率の良い改修が工場全体で最も迅速な選択肢であるという一文のメッセージを受け取りました。.
この出版物は、電力トランスに関するエネルギー効率の良い改修の概念、交換との比較、経済的運用慣行の種類、関連するコスト、そして正確な回収期間の計算方法について説明しています。.
トランスのエネルギー効率の良い改修という用語は、通常、エネルギー集約型のコアや巻線をエネルギー効率の良いものに置き換えること、またはほとんどの場合、新しいエネルギー効率の良いタイプのトランスに完全に交換することを指します。これはGB 20052またはIEC分類に従います。改修には新しいトランスの60-80%のコストがかかることがありますが、性能は新しいトランスを使用する場合と同等であり、このような解決策はエネルギー効率の良いプロジェクトでは一般的ではありません。しかし、適切なサイズ、負荷管理、タップの調整、損失捕捉などの経済的運用措置は、投資を1年未満で回収することができます。.
トランスのエネルギー効率の良い改修の意味
エネルギー効率の良い改修という用語は、トランスの損失を減少させるために行われる変更または交換を指します。損失には2種類あり、最初のものは無負荷損失で、トランスが何らかの形で負荷されているときに発生し、負荷には影響されません。負荷損失は負荷の二乗に基づいています。トランスの場合、両方のタイプの損失には価値がありますが、その価値はトランスの運用方法によって大きく異なります。.
改修には以下のアクションが含まれます。最初の方法は新しいトランスを購入すること、2番目は既存のトランスを巻き直すかコアを交換すること、3番目は負荷管理または冷却技術を追加すること、最後は運転ポイントを再設計すること（負荷を駆動する必要があるか、並行して作業するか、その他の方法で）です。.
トランスの損失を理解する：無負荷対負荷
これは無負荷損失（または鉄損失）と呼ばれ、損失はコアを単独で磁化することによって発生します。フルロードで動作しているかどうかにかかわらず、このエネルギーの損失は毎年8760時間発生し、エネルギー節約の努力において最も重要な要素となります。負荷損失（または銅損失）は、巻線を通過する電流によって発生し、電流の二乗に応じて変化します。言い換えれば、変圧器が50%の負荷で動作している場合、定格負荷損失のうち25%のみが記録されます。.
| 変圧器のサイズ | 古い設計の無負荷損失 | 現代のGB 20052-2グレード2 | アモルファスコア（グレード1） |
|---|---|---|---|
| 100 kVA | 270–350 W | 130–180 W | 60–90 W |
| 400 kVA | 800–1,100 W | 400–520 W | 180–260 W |
| 1,000 kVA | 1,500–2,100 W | 700–1,100 W | 350–500 W |
| 2,500 kVA | 3,200–4,500 W | 1,600–2,400 W | 800–1,200 W |
示されているように、古い変圧器のコア損失は一般的に現代のモデルの2倍、アモルファスコアモデルと比較すると3倍から5倍高くなります。これらの損失が24時間365日発生することを考えると、年間のコストの変動は重要です：kWh料金が0.10の場合、無負荷損失のケースでは総損失の差は$876になります。.
現場での改修 vs 完全交換
既存の変圧器の巻き直しとコアの再加工は、製造業者にとって可能性があり、タンクと付属品が良好な状態であり、変圧器に特異な定格がある場合や、グリッドコードやサイトの制約が同等の交換を行う機会を与えない場合には、正しい選択かもしれません。.
しかし、ほとんどの場合、数字はこの決定に対して反対のことを示します。.
- 現場での巻き直しは新しい変圧器の約60-80%のコストがかかりますが、古いタンク、古いガスケット、ブッシング、オイルを持つユニットが残り、過去の故障の削減はありません。.
- 現代のユニットに交換することは、現代の鋼の効率的な利点、新しいタンク、絶縁、保証、メンテナンスコストの削減を得ることを意味します。.
- 規格は変わっています：2005年に購入した変圧器はGB 20052に適合できません。現代の基準は異なるため、1995年以前に取得した変圧器は言うまでもありません。古いコアでは基準に適合することは不可能で、必要な0.9 kWの代わりに約1.8 kWの損失が示されます。.
実用的なルールは、物理的な理由やサイトの制約で交換ができない場合にのみ改修を行うことです。そうでなければ、許可されている最高効率クラスに交換する必要があります。.
| オプション | コスト vs 新しいユニット | 無負荷損失の結果 | 保証 | 最適な時 |
|---|---|---|---|---|
| 現場での再巻き | 新しいものの60–80% | 古いコアが残り、わずかな利益 | 巻き直しのみ | 特異な定格、固定されたサイト制約 |
| 現場での再コア加工 | 新しいものの70–90% | 新しいコアだが古いタンク/ブッシング | コアのみ | 経済的であることはまれ |
| 完全交換、グレード2 | 100% | 1990年代のユニットの半分 | 完全ユニット、12–24ヶ月 | 標準的な回収ケース |
| 完全交換、アモルファスコア | 120–140% | 60–70% below conventional | 完全ユニット、12–24ヶ月 | 24/7 loaded applications |
The reason why consultants advocate for replacing systems is illustrated in the chart; the difference between the cost of a retrotfit and what it achieves is typically greater than the difference between the cost of a new unit and the savings it generates.
Energy-Saving Technologies to Specify
When you buy a new transformer for energy saving, four technology choices matter:
| 技術 | Typical no-load loss saving | Extra first cost | Best payback condition |
|---|---|---|---|
| High-permeability GOES (0.23 mm) | 15–25% vs standard grade | +3–6% | Nearly always positive on TCO |
| アモルファス金属コア | 60–70% vs conventional core | +20–40% | High-load-factor, 24/7 operation |
| Low-loss winding design (higher copper mass) | 10–20% lower load loss | +2–5% | Heavily loaded transformers |
| Natural ester (vegetable) oil | Same as mineral oil electrically | +10–15% | Fire-safety and sustainability priorities |
The amorphous alloy should be examined very carefully when we consider 24-hour applications like data centers, hospitals, or continuous process plants because the transformer will be under load around the clock. Higher initial costs are offset through savings made because of lower losses in the core; on average, it takes an amorphous-core 1,000 kVA transformer 4–8 years to recoup its extra costs when compared to any standard high-efficiency transformer.
Economic Operation: Optimizing What You Already Own
Economic operation is about managing transformers that one owns in the most effective way. It brings very little cost and often has a payback period measured in terms of months:
- Identify an optimal size fleet: analyze the loading pattern and consider replacing two transformers with the loading less than 40% with one transformer. The operating costs of transformers go down.
- Control parallel operation: in case there are two transformers operating at the same time, there is very little point to keep the first transformer working in the case of light loading of the second transformer.
- Set taps correctly: choosing tap position that would keep the voltage on the lower edge of the acceptable area results in decreasing magnetizing current and excitation current.
- Keep the transformer operating at low temperatures: this is important because clogged radiators raise oil temperature and accelerate insulation aging.
- Observe transformers’ losses with a metering plan: measure no-load loss during a shutdown period and load loss during peak, then use it in a loss-capitalization model.
Distribution companies that manage to switch off one out of two operating transformers overnight usually save 40-60% of losses due to the process — thus, it becomes clear that changing one switch can save thousands of dollars.
| Economic operation measure | Capital cost | Typical saving | Payback |
|---|---|---|---|
| Switch off redundant parallel unit at light load | None | 40–60% of bank’s overnight no-load losses | Immediate |
| Optimize tap positions for voltage band | None | 1–3% of transformer losses | Immediate |
| Clean radiators, restore cooling | Maintenance labour | Lower hot-spot ageing, extended life | <1 year |
| Replace two lightly loaded units with one | New unit | One unit’s no-load loss eliminated | 3–8 years |
| Add loss metering and trend review | $500–$2,000 | Identified loss issues worth $1,000s/yr | <1 year |
It has been observed that the same pattern is consistent: the operating measures can be recouped with immediate effect. However, the capital measures follow the loss-capitalization pattern. A facility that applies both approaches reaps full benefits.
Calculating Payback and Loss Capitalization
Loss capitalization is a professional approach to evaluating alternatives: calculations must be performed in order to gain the present value of each watt of no-load loss and load loss occurring during the life of a transformer, then the first cost shall be added, and the cheapest total cost shall be selected. The provided formulas can be used for that purpose:
- Annual no-load loss cost = no-load loss (kW) × 8,760 h × tariff ($/kWh).
- Annual load loss cost = load loss (kW) × hours in a year × load factor² × tariff.
- Present value for 20 years should be approximately equal to annual cost multiplied by 9.8 (at the discount rate of 8%).
As an example, it would be possible to compare a GB 20052 grade 2 1,000 kVA unit (with no-load of 1,000 W and load of 10,000 W) with the use of an amorphous grade 1 unit (with no-load of 500 W and load of 10,000 W) and with the tariff of $0.10/kWh at the load factor of 40%. In this situation, it can be stated that the grade 1 unit will help save $438 in terms of no-load loss only; thus, the present value will amount to around $4,300 over 20 years, while the first cost will constitute about $2,000-3,000, which demonstrates evident advantages of the amorphous unit in case of operation.
A Step-by-Step Retrofit Process
- Audit: Take account of the nameplate data, test records, load curves, and tariff structure of the transformer.
- Test: Wherever applicable, conduct no-load loss tests and examine DGA and oil condition during the shutdown.
- Model: Make a comparison between the keep, retrofit-in-place, and replace with a grade-1/2 methods in terms of losses capitalization.
- Budget: Affirm the budget, and check to see if the efficiency incentive programs are applicable (many regions subsidize the amorphous core and grade-1 transformers).
- Procurement: Specify the requirements of the IEC 60076 testing standard, GB 20052 standard for efficiency rating, and require test reports.
- Install and verify: Check the ratio on-site and conduct no-load loss tests, then adjust the transformer settings and installation settings.
- Monitor: Make logs of energy consumption and compare it with the baseline model for one year.
The failure to perform the audit step is the most common mistake made by organizations since the practice leads to changing the transformers that whose operations are already cost-effective and at the same time keeps the inefficient units in place.
Costs by Brand and Efficiency Class
Prices for a new 1,000 kVA 10/0.4 kV energy-saving distribution transformer, FOB by brand and efficiency class:
| ブランド | 起源 | Standard efficiency | High efficiency (grade 1 / amorphous) |
|---|---|---|---|
| 日立エナジー | Japan/Global | $8,500–$12,000 | $12,000–$17,000 |
| ABB | Switzerland/Global | $8,000–$11,500 | $11,500–$16,500 |
| シーメンスエナジー | Germany/Global | $7,500–$11,000 | $11,000–$15,500 |
| シュナイダーエレクトリック | France/Global | $7,000–$10,500 | $10,500–$15,000 |
| 江蘇省蘇辺電力 | 中国 | $4,000–$6,500 | $5,500–$8,500 |
Price quotes may vary due to the loss class, tap changers, accessories, copper prices, and delivery conditions. Treat them as planning ranges, not firm quotes.
Well-known brands prove their quality through global service networks and extensive type testing. The argument in favor of the Chinese tier is that their products have the same test results according to IEC 60076 and the same efficiency according to GB 20052 but 40%-50% cheaper in the first cost. Jiangsu Subian Electric Power is a Chinese manufacturer of liquid-immersed transformers with efficiency grades of GB 20052 with capacity up to 63 MVA.Subian has supplied energy-saving retrofits to utilities and industrial parks across Asia, Africa, and the Middle East, and its range is documented on subian-electric.com.
よくある質問
How much does an energy-saving transformer cost?
A high-efficiency 400-kVA transformer costs between $2,500 and $4,500, and a 1,000-kVA transformer costs $4,000 to $8,500, delivered freight-on-board (FOB) from suppliers in China. The latter includes transformers with intermediate performance, while models with the best quality (class 1 amorphous core) cost more. European and Japanese transformers typically cost between 50 and 80 percent more than those manufactured in China. The costs of transformers vary depending on their classes of losses and accessories as well as raw material prices.
Is it cheaper to re-wind an old transformer or buy a new one?
Winding normally costs between 60 and 80 percent of what a new unit costs, yet provides the same or worse performance than the old unit using old gaskets and bushings and no new warranty apart from the process of rewinding. Unless a new transformer cannot be installed for technical reasons, changing it for a modern low-loss one will typically prove to be a more viable economic option.
How much electricity does an old transformer waste?
Generally, a 1990s 1,000 kVA unit has losses in the range of 1,500-2,100 W in no load situations, resulting in 13,000-18,000 kWh annually, valued at $1,050-$1,800 (assuming an electricity rate in the range of $0.08-$.0.10/kWh). A modern grade 2 unit would bring those losses down to one half, which can be reduced once again with an amorphous core design.
What is a good payback period for replacing a transformer?
Usually, the time for the replacement of an old conventional equipment with a new energy-efficient is 3–8 years in operation mode. This time can be determined by cost tariffs and load factors. Economic management techniques such as equipment sizing, parallel operations and tapping usually return the investment within 1-2 years, with minimum or no capital investment being needed.
How do I know which efficiency grade to buy?
Perform loss-capitalization based on the current tariff and load factor. At high-loading and high load factor sites, go with the best product available (GB 20052-2 class 1 or amorphous core). At lightly-loaded and seasonal sites, class 2 is often the best option because the difference in no-load loss does not warrant the price difference.
参考文献
- IEA Energy Efficiency 2023 — Global context on transformer efficiency and loss reduction policy.
- IEC 60076-1: Power transformers – General — Rating and testing basis for loss verification.
- GB 20052: Energy efficiency grades for power transformers (China) — The efficiency grade standard used across the sector.
- US DOE transformer efficiency program — North American efficiency rules and loss economics.
- Hitachi Energy transformer portfolio — Reference for premium energy-saving transformer offerings.
- Jiangsu Subian Electric Power official site — Energy-saving and amorphous-core transformer range with test reports.
結論
Transformers’ energy-efficient upgrades and their effective exploitation are among the most rewarding energy projects for power producers and industrial companies. Not due to the fact that this technology is complicated, but rather because obsolete transformers are working overtime, discharging electricity while barely being noticed. By examining the technology on a structural level, loss-capitalization approach, and energy-efficient operation, one can easily achieve a payback of 3–8 years for replacement, and 1–2 years for operation modifications.
The main conclusions one can draw from here are as follows:
- No-load losses number 8,760 hours/year, and switching a transformer manufactured in the 1990s to a state-of-the-art low-loss unit usually lets one achieve a 50 percent loss drop.
- In-place modifications can hardly succeed in getting lower TCO than the replacement.
- The quickest payback of the investments can be achieved by the use of energy-efficient operation without investment.
- Amorphous core transformers have good payback in case the equipment is in high demand.
If your facility is evaluating an energy-saving retrofit, 江蘇省蘇辺電力 supplies GB 20052 grade 1–2 transformers with documented no-load loss test results, including amorphous-core designs, at export-friendly prices. Start with the audit — the range is on subian-electric.com.