45 kmのメトロラインの牽引電力エンジニアとして、1日あたり80,000人の乗客を輸送できる能力を持ち、90秒の間隔で運行するために、35kV ACからなる牽引電力システムを利用します。このAC配電は、エネルギーを750V DCに変換する12の牽引電力変電所に電流を供給します。この750V DCは、サードレールを介して供給されます。このプロセスが行われる同時に、駅内の照明、エスカレーター、換気ファン、信号用の補助電力を供給するための別の完全な変圧器セットも存在します[1]。.
鉄道輸送における変圧器の作業に必要な電気工学スキルのレベルは、他のアプリケーションとは全く異なるレベルです。この記事では、牽引整流器変圧器、補助変圧器、IEC基準への適合を確保するための対策、熱放散、ハーモニック電流、衝撃耐性に関する問題への対処方法を含む、鉄道輸送における変圧器のさまざまな設計要件について説明します。.
鉄道変圧器が異なる理由
鉄道輸送用変圧器は、牽引電力の品質、駅の信頼性、資産の寿命という3つの厳しい条件の交差点で動作します。産業用のものとは具体的に異なります：
| 稼働パラメータ | 工業プラント | 鉄道輸送 |
|---|---|---|
| 負荷サイクル | 予測可能なシフト、数時間 | 5分ごとのピーク/オフピークサイクル |
| 電圧範囲 | ±10%が一般的 | +12%/−18%（EN 50163による） |
| 負荷電流の形状 | ほぼ正弦波 | 整流されたDC、重いハーモニクス、時折のDC成分 |
| 短絡頻度 | 稀 | サードレール/カテナリーで頻繁 |
| 設置 | アクセス可能な部屋が多い | 地下のバルト、線路脇、振動にさらされる |
| 資産寿命の目標 | 一般的に20年 | メトロ仕様では30年が一般的 |
これらの違いは、短絡を制限するためのインピーダンスの増加、可変電圧運転を可能にするための良好な絶縁、急速な熱サイクルに対応するための冷却、地震衝撃に耐えるタンクを含む、すべての牽引変圧器の入札に特別な仕様をもたらします。.
牽引整流器変圧器
牽引整流器変圧器は、DC牽引供給システムの中心的なコンポーネントを表します。この変圧器の目的は、AC供給電圧（10、20、または35 kV）を、このアプリケーションの整流器入力電圧に減少させることです。これらは一般的に750 V DCシステム用の590〜1,180 V ACの範囲であり、1,500 V DCシステム用には1,180 Vを超え、最大2,360 Vになる可能性があります。.
| DCシステム | 整流器変圧器の定格 | 一般的なインピーダンス | 変電所ごとの供給距離 |
|---|---|---|---|
| 750 V DC（サードレール、メトロ） | 2×1,800–2×3,000 kVA | 6–8% | 2–4 km |
| 1,500 V DC（カテナリー、都市鉄道） | 2×2,500–2×4,500 kVA | 8–12% | 4–8 km |
| 3 kV DC（レガシー主幹線） | 2×3,000–2×6,000 kVA | 10–12% | 8–15 km |
牽引整流器変圧器の構造において重要な要素は3つあります。.
高調波成分：整流器は、高調波（5次、7次、11次、13次）の豊富な非正弦波電流によって特徴付けられ、非対称点火がある場合には、コアを不適切にバイアスし、過熱を引き起こす可能性のある小さな直流が含まれることがあります。したがって、変圧器は巻線損失のためにより高いマージンで構築されるべきです。.
インピーダンス値：6–12%インピーダンスは、第三軌条の故障に供給される短絡電流の制限を提供し（これは1日に数回発生する可能性があります）、整流器のコミュテーションを指定します。この値は、保護と調整の妥協の結果を表しています。.
過負荷能力：トレーリングサービスは過負荷を許可し、EN 50329（牽引変圧器に適用される標準）は、例えば150%で5分間または300%で1分間の過負荷サイクルを指定しており、その間、変圧器は故障のリスクなしに動作することができます。.
2×2,500 kVA牽引整流器変圧器のコストは、ブランド名、冷却方法、および地下駅用の防音ハウジングの有無に応じて$45,000–$120,000です。.
補助および側道駅変圧器
Besides, the auxiliary transformers are also necessary for every station. These take care of the station services, i.e., lighting, escalators, ventilation, pump, fire systems, and signaling system.
Signaling power supply: the signal unit and train control systems need supply with no voltage variation of more than ±10% and power cuts of not more than 10 ms. This requires the use of a dedicated voltage conditioner transformer.
Station auxiliary loads: 500–2,500kVA dry-type transformers are primarily used in the form of auxiliary transformers; these capacitors are necessary for underground environment safety.
Wayside equipment: these are smaller units of 100–500kVA used for powering level crossings, signals, and trackside telecommunications.
Auxiliary station transformers can cost between $15,000 and $40,000 for a 1000–2500 kVA transformer. They are also made to have a life of more than 30 years, monitored, and maintained, since a failed transformer can effectively shut down any station.
Standards Governing Rail Transformers
Rail transformer procurement references a specific set of standards that buyers in other industries rarely see. Knowing them is essential for a compliant tender:
| 標準 | 範囲 | Why It Matters |
|---|---|---|
| IEC 60076 (series) | Base transformer design and testing | Foundation for all rail transformer ratings and tests |
| EN 50163 | Supply voltages of traction systems | Defines the +12%/−18% voltage range the transformer must handle |
| EN 50329 | Traction transformers and their cooling | Defines traction overload cycles and thermal design rules |
| IEC 60310 | Traction transformers on rolling stock | Covers on-board transformers for trains themselves |
| EN 50121 | EMC for railway applications | Electromagnetic compatibility limits for substation equipment |
| EN 50122-1 | Protective provisions relating to electrical safety in traction systems | Earthing and bonding requirements for substations |
There are two installations to note. EN 50329 is the metric standard used by the majority of metro authorities in overload cycles and thermal testing; it is the document that turns the phrase “150% for 5 minutes” from a casual saying into something that has undergone testing. EN 50121 deals with electromagnetic compatibility and is usually the first standard to be violated by suppliers of low-cost equipment since traction substations have to work adjacent to signalling installations unaffected by switching currents from the inverter.
Special Requirements: Voltage, Harmonics, Thermal Shock
Four specific requirements pose persistent challenges to transformer manufacturers in rail projects, which should be explicitly specified in tenders.
1. Wide voltage range (EN 50163): The transformer together with its tap changers shall keep the output voltage within +12%/−18% of nominal voltage. This issue is solved with the help of on-load tap changers, if any, or by providing sufficient design margins in the winding.
2. Harmonics and DC resistance: As current is distorted by the rectifier load and may inject DC bias, the windings should be designed with increased losses margins as well as core flux/headroom. Details of this issue are revealed by temperature rise tests in rated and overloaded conditions.
3. Thermal cycling: Quick load changes make the windings heat and cool every few minutes, putting mechanical stress on insulation. Overloads tests according to EN 50329 and thermal cycling verification distinguish rail units from industrial ones.
4. Shock, vibration, and noise: While underground and trackside installations require seismic restraints and vibration damping, the noise level is to be limited for adjacent station gear to become less than 65 dB(A).
For the customer, this translates into the following: if a quotation for standard distribution transformer is offered for traction rectifier purposes this shows a lack of understanding the issue. The unit should pass type tests according to EN 50329 or similar requirements including tests in overload conditions and the related report should not only include IEC 60076 temperature rise tests.
Innovative Solutions from Manufacturers
Transformer manufacturers have responded to these demands with a set of innovative solutions that are now standard features in rail-grade equipment:
| Innovation | Problem Solved | Typical Implementation |
|---|---|---|
| Enhanced winding cooling ducts | Rapid thermal cycling | Axial and radial ducts sized for peak-short-duration heat pulses |
| DC-bias-resistant core design | Rectifier DC component | Larger core cross-section and flux margin with higher-grade steel |
| Integrated fiber-optic temperature sensing | Hot-spot management in overloads | Winding-embedded FBG or fluoroptic sensors feeding the DCS |
| Low-noise enclosures and acoustic cabins | Station noise limits <65 dB(A) | Double-wall tanks, damping liners, resilient mounting |
| Sealed, maintenance-free designs | Underground vault access constraints | Welded tanks, nitrogen-blanketed or gas-adsorption oil preservation |
| Digital twin / online monitoring | 30-year asset life assurance | DGA, partial discharge, and load profiling with remote analytics |
In the case of new metro projects, the norm is full monitoring of traction transformers where there’s online DGA and partial discharge detectors feeding data to the operations control center. This is not a luxury — in fact, traction transformers are the only assets which can incur an unpredicted failure leading to the immediate disruption of revenues, forcing operators to treat monitoring not simply as an option but as a necessity.
Specification Checklist for Rail Projects
Indicate the DC voltage levels (750 V / 1,500 V / 3 kV), as well as the AC supply voltage and frequency in accordance with the EN 50163 voltage range and the EN 50329 overload cycle requirements (150% for five minutes and 300% for one minute, according to project-specific duty). State the impedance range that can be used in limiting short-circuiting, confirming it with the protection study.
Requiring the design to be resistant to harmonic and DC components, ask for tests for temperature rise with the use of rated characteristics and loads with harmonics.
Specify the environmental conditions, including an underground vault and trackside, altitude above sea level, and humidity level.
Specify the maximum noise levels (normally 65-75 dBA) and seismic/vibration qualifications. Ask for online monitoring options (DGA, PD, and temperature) to be implemented for new units.
Ask for the documents proving that tests comply with EN 50329 or equivalent. Define the 30-year lifetime of the equipment and ask for the spare parts supply.
Verify compliance with EMC according to EN 50121 before the delivery.
Top Brands & Price Comparison
The market of traction transformers is ruled by manufacturers that have established themselves by supplying metro and main line systems. The table provides cost estimates for a 2×2,500 kVA, 35 kV traction rectifier transformer; however, the actual prices depend on impedance, cooling means and noise enclosure.
| ブランド | Country | Rail Portfolio Strength | Indicative Price (USD) |
|---|---|---|---|
| Siemens | Germany | Full traction power ecosystem, extensive metro references | $70,000–$120,000 |
| ABB | Switzerland | Rectifier and converter integration heritage | $65,000–$115,000 |
| 日立エナジー | Japan/Switzerland | Strong rail power and traction transformer track record | $75,000–$120,000 |
| シュナイダーエレクトリック | France | Substation and auxiliary power packages | $60,000–$105,000 |
| Alstom (supply chain) | France | Traction system integration for rolling stock and fixed power | Project-specific |
| Jiangsu Subian Electric Power | 中国 | IEC/EN-compliant traction rectifier and auxiliary transformers, OEM | $45,000–$80,000 |
The known suppliers in Europe and Japan have decades of experience in metro references, extensive experience in the EN 50329 type-test, and the capability to provide complete traction power packages. They are the only ones qualified to bid in many flagship metro projects with tough local-content specifications. Jiangsu Subian Electric Power is working on closing this gap for international rail projects, supplying IEC 60076–compliant rectifier and auxiliary transformers built to the EN 50329 overload specifications that are priced at around 40–60% of the European prices. Metro authorities and EPC contractors that are comparing offers can take the practical route of selecting a certified supplier like Subian along with other major world suppliers, confirm EN 50329 type-test certificates and factory test protocols, and use the cost difference to finance the surveillance and spare part packages.
よくある質問
What is the typical rating of a metro traction rectifier transformer?
The DC metro system that operates at 750 volts typically employs two transformer rectifiers with ratings of either 2,1000 kVA or 2,3000 kVA at every traction substation. The 1,500 V DC system employs 2 ideal transformer rectifiers with ratings of either 2,8000 kVA or 2,4500 kVA.
Why do rail transformers cost so much more than industrial transformers?
A 2×2,500 kVA traction rectifier transformer costs $45,000–$120,000 versus $9,000–$18,000 for a similar-size distribution unit. The premium covers EN 50329 overload-capable windings, harmonic and DC-bias resistance, 30-year design life, low-noise construction, seismic qualification, and type testing — plus the documentation burden of rail procurement.
What voltage range must a traction transformer withstand?
Per EN 50163, traction systems must operate over +12%/−18% of nominal voltage. For a 25 kV system that means 19–28 kV, and for a 35 kV supply roughly 28.7–39.2 kV. The transformer and its tap changer must regulate output across this whole range, which is why OLTC is common on large traction units.
Can a standard distribution transformer be used for traction duty?
Only with extensive re-engineering, and most metro authorities will not accept it. Traction duty adds rectifier harmonics, a possible DC component, rapid thermal cycling, and frequent short circuits. A standard unit will overheat under the EN 50329 overload cycle and age prematurely — typically failing in 5–8 years instead of the required 30.
What monitoring should a modern traction transformer have?
Best practice for new metro projects is online DGA plus partial discharge sensing, winding temperature via fiber-optic sensors, and load profiling feeding the operations control center. This typically adds $6,000–$20,000 per unit but converts the transformer from a reactive-maintenance item into a managed asset with predictive capability.
References
- EN 50329 — Railway applications: Fixed installations, traction transformers — the traction-specific standard defining overload cycles and thermal design rules.
- EN 50163 — Supply voltages of traction systems — defines the +12%/−18% voltage range for traction equipment.
- IEC 60076 series — Power transformers — the base design and testing standard referenced by all traction transformer tenders.
- IEC 60310 — Traction transformers on rolling stock — on-board transformer requirements for trains.
- EN 50121 — Railway EMC standards — electromagnetic compatibility limits for traction substation equipment.
- Railway Gazette — industry reporting on metro, tram, and traction power project specifications.
- Jiangsu Subian Electric Power — official site — manufacturer of IEC-compliant traction rectifier and auxiliary transformers for rail projects.
Conclusion
The transformers employed in railway systems are exposed to an operational profile unlike any other used by any industrial application: they are expected to endure rapid thermal cycling at minute intervals, to handle large voltage fluctuations, to deal with harmonics generated by the rectifier, to be able to withstand frequent short circuits, and to last for 30 years in service. Therefore, it is crucial to fulfill these requirements by adhering to the relevant standards, specifically, EN 50163 and EN 50329; by properly determining the impedance and overload capacity; by demanding proof of compliance with the required types of tests; and by implementing modern monitoring systems into the units that allow one to predict the failures instead of detecting them.
Main points:
Select the traction units according to EN 50329 overload cycles and EN 50163 voltage requirements.
Make sure to check the impedance against the data from the short circuit study; the value of 6-12% is normal.
Require that the core of the transformer is DC bias resistant and that the windings are capable of working with harmonics.
Add real-time monitoring of numerous parameters to ensure the safety of investment.
For traction power and auxiliary transformer supply on metro, tram, or mainline projects, contact Jiangsu Subian Electric Power at www.subian-electric.com.