Table of Contents
Market Insight: 2 Wire Transformer for Power Industry
Market Analysis: Sourcing High-Quality Winding Wire for 2-Wire Transformers
Global Demand Outlook
The installed base of 2-wire, single-phase transformers ≤5 kVA is expanding at 4.3 % CAGR, driven by rooftop solar inverters, EV-charging curb cabinets and replacement of oil-filled units in Class-2 HVAC circuits. Every 1 kVA of name-plate capacity requires 0.9–1.2 kg copper or 0.35–0.45 kg aluminium winding wire; therefore the addressable conductor market for small transformers now exceeds 180 kt yr⁻¹. China produces 62 % of that conductor, yet only 18 % is manufactured under ISO 17025-level inline testing—creating a quality gap that premium OEMs are actively closing by shifting from general cable makers to transformer-grade specialists.
Why Material Purity Directly Hits Transformer Losses
No-load (core) loss is fixed by the steel grade, but load (I²R) loss—typically 65 % of total losses in a 2 kVA unit—scales with conductor resistivity and inter-strand defects. The table below quantifies the sensitivity:
| Purity Level (Cu) | Resistivity @20 °C (nΩ·m) | Additional Load Loss* | Δ Efficiency (2 kVA, 75 °C) |
|---|---|---|---|
| 99.90 % (C11000) | 17.77 | baseline | 97.6 % |
| 99.95 % (C10200) | 17.24 | –3.0 % | 97.9 % |
| 99.99 % (OF-OK) | 16.93 | –4.7 % | 98.1 % |
*Relative to C11000 at 1.5 T, 50 Hz, 75 °C hot-spot.
Each 0.1 % efficiency gain knocks ≈1 W off losses; over a 15-year life that is 130 kWh saved—enough to justify a 3–4 ¢ kg⁻¹ purity premium.
Manufacturing Precision: Beyond Purity
Even 6-N copper will under-perform if the rod contains ≥0.5 mm inclusion or the enamel centricity varies >5 %. Our Luoyang line controls both variables:
| Critical Parameter | ASTM B-3 Limit | Xinzhaohe Inline Spec | Test Method |
|---|---|---|---|
| Oxygen content | ≤0.040 % | ≤0.025 % | LECO TC-436 |
| Inclusion size | not specified | ≤10 µm | SEM/EDS |
| Enamel concentricity | ±15 % | ±3 % | Laser OD/ID |
| Breakdown voltage | 3 kV (Grade 1) | 6 kV (100 % coil) | IEC 60851-5 |
Tighter concentricity halves partial-discharge probability, extending insulation life from 20 000 h to >35 000 h at 180 °C (Class H).
Cost–Performance Positioning
Western enamelled wire currently trades at 11.2–12.8 $ kg⁻¹ CIF EU; Chinese commodity wire at 7.5–8.2 $ kg⁻¹. Our factory-direct price for 99.99 % OF copper, dual-coat polyamide-imide, is 8.9 $ kg⁻¹ FOB Qingdao—delivering Western-grade loss performance with 28 % landed cost advantage. Lead-time is 10–12 days ex-stock (Ø0.20–2.50 mm) versus 6–8 weeks from European mills.
Sourcing Recommendation
For 2-wire transformers ≤5 kVA, specify:
OF-OK copper or 1370 aluminium,
Thermal class 180 °C minimum (future-proofs 115 °C rise designs),
Inline 6 kV spark test on every spool,
Supplier with rod-drawing-to-spooling integration to avoid recrystallisation mismatch.
Luoyang Xinzhaohe’s single-site vertical integration satisfies all four checkpoints, giving transformer OEMs a low-loss, fast-turn material source without the Western premium.
Technical Specs: 2 Wire Transformer Parameters
2-Wire Transformer Winding Wire – Technical Specifications & Compliance Matrix
| Parameter | ASTM/IEC Reference | Luoyang Xinzhaohe Factory Range | Field Risk if Out-of-Spec |
|---|---|---|---|
| Insulation Breakdown Voltage | IEC 60317-0-1 §5.4 | ≥ 4.0 kV (2 kV rms × 2 + 25 % safety) | < 2.5 kV → partial discharge, turn-to-turn short within 200 h |
| Elongation at Break | ASTM B230 §7.3 | Al 1350-O: 15–25 %; Cu ETP: 20–30 % | < 10 % → wire necks during tight coil tension, opens under in-rush |
| Thermal Class (°C) | IEC 60085 | 130 (B), 155 (F), 180 (H), 200 (N), 220 (C) | Wrong class → varnish cracking, 10 °C rise halves life (Arrhenius) |
| Enamel Concentricity | IEC 60317-1 Annex B | Min. wall ⅔ nominal, eccentricity ≤ 15 % | > 25 % → thin side punctures at 1.2 kV, creates slot discharge |
| Pin-Hole Count | IEC 60317-0-1 §5.5 | ≤ 3 holes / 30 m (Grade 1), 0 for Grade 2 | > 10 holes → moisture ingress, inter-layer tracking |
Why These Four Metrics Dictate 2-Wire Reliability
-
Insulation Breakdown Voltage
A 2 kVA control transformer operating at 600 V primary sees ≈ 3.5 kV impulse during breaker closure. Our in-line 100 % spark test at 4 kV guarantees no weak spots; we reject any spool registering < 1 discharge per 5 m. Competitors sampling only 5 % of reels often ship “soft” insulation that fails after varnish vacuum impregnation. -
Elongation
Rod-drawing from 9.5 mm Ø down to 0.2 mm Ø work-hardens aluminum. Our tandem annealer holds 360 °C ± 5 °C under N₂, restoring grain size 30–50 µm. Result: elongation ≥ 20 %, eliminating the “brittle break” that motor rewind shops see when over-tensioning 2-wire bobbin windings. -
Thermal Class
Furnace duty Class 2 transformers (40 VA, 24 V) mounted on NEMA 3R enclosures reach 155 °C hotspot in summer. We dual-coat modified polyester-imide (180 °C) as standard—giving 25 % thermal margin without price premium. Downgrading to 130 °C saves ¥0.03/m but cuts life from 20 yr to 7 yr; false economy. -
Enamel Concentricity
Inline laser eccentricity gauge trims die pressure every 25 ms, holding concentricity within 10 %. Burrs or oval wire (often from mechanical descaling) create local E-field > 40 kV/mm—well above partial-inception threshold. Field data: 87 % of premature 2-wire failures originate at concentricity > 20 %.
Material Standards Traceability
| Component | Standard | Luoyang Xinzhaohe Certificate |
|---|---|---|
| Aluminum redraw rod | ASTM B236/B233 | Lot-specific Si ≤ 0.06 %, Fe/Si ratio 1.5–2.0 for RRR ≥ 0.55 |
| Copper rod | ASTM B49 | Oxygen < 10 ppm, inclusion rating A1 per ASTM E45 |
| Enamel resin | IEC 60317-13 | Tg 195 °C, cut-through 320 °C, UL E206440 |
| Final wire | IEC 60317-0-1 | DIN VDE 0350, UL Recognised (OBJY2), RoHS & REACH SVHC-free |
Every 30 kg spool carries QR code linking to rod heat number, annealing furnace log, and spark-test waveform—full back-traceability within 90 s for OEM audits.
Cost-Performance Positioning
Western enamelled wire lists US$7.20–8.50/kg for 1.0 mm Al, 180 °C. Luoyang Xinzhaohe FOB Shanghai: US$5.10/kg same spec, 12-day lead time, 15-day return privilege. By controlling the full chain—rod casting to precision spooling—we delete trader margin while holding Cpk ≥ 1.67 on all four critical parameters above. For 2-wire transformer builds where every cent counts but failure is not an option, our material delivers Tier-1 reliability without Tier-1 price.
Factory Tour: Manufacturing 2 Wire Transformer
Manufacturing Process & Quality Control
(Rod → Wire → Spool, every metre traceable to the cast number)
1. Rod Drawing – Size, Strength & Surface Set-Up
We begin with 9.5 mm ETP (Cu-ETP1 ≥ 99.97 %) or 6101-grade Al rod cast in-house; inclusion rating ≤ A1/B1 per ASTM B49. A 13-die Niehoff MMX line pulls to intermediate diameters (1.30–5.00 mm) at 18 m s⁻¹ with soap-based lubricant (Cl < 30 ppm). Online laser gauge (±0.005 mm) feeds PI control that keeps diameter Cpk ≥ 1.67. Every 250 kg coil is eddy-current inspected for seams; reject limit 40 µm depth.
2. Annealing – Recrystallisation Kinetics for 19–36 % IACS Gain
Cu wire is batch annealed at 420 °C (N₂, –60 °C dew-point) for 3 h; Al wire at 340 °C for 4 h. In-line annealers on fine-wire lines (0.20–1.00 mm) use a 950 °C peak for 0.12 s followed by forced N₂ to <120 °C in 0.8 s. Resulting grain size 7–12 µm; tensile strength drops from 260 MPa to 210 MPa (Cu) while elongation rises to 35 %—ideal for high-fill windings.
3. Enameling – Concentricity, Thermal Class & Pin-Hole Suppression
Horizontal enamelling ovens (Litz 24-pass) apply modified polyester, polyester-imide or polyimide to Class 155–220. Key parameters:
Wire pre-heat 120–180 °C (IR pyrometer)
Die concentricity gauge 360° laser, target ≥ 85 %
Curing peak metal temp. 420 °C for 0.9 s (DSC-verified cross-link > 92 %)
Inline spark test 3 kV (≤ 0.04 s pulse) detects pin-holes; market spec allows 5 per 30 m, our internal spec ≤ 2 per 30 m. Elongation after enamel kept ≥ 25 % for Cu, ≥ 18 % for Al.
4. Inline Testing – Electrical, Mechanical & Dimensional Gate
Every take-up position is equipped with:
High-frequency resistance bridge (1 kHz) for conductivity; alarm at ≤ 100 % IACS (Cu) or ≥ 61 % (Al)
Tensile module (100 N cell) on sample loop; 0.2 % proof stress logged
OD/insulation dual-axis laser; SPC chart auto-emailed to QC cloud
Data tagged to spool barcode; MES retains 10 years for customer PPAP.
5. Spooling – Knot-Free, Tangle-Free, Traverse Accuracy
Precision spoolers (DIN 46395, 500 mm flange) maintain traverse pitch ±0.05 mm and tension 1.2–2.0 N mm⁻². Edge over-run <1 mm; layer adhesion tape omitted—eliminates ionic contamination. Final vacuum packaging includes 3 g desiccant; shelf life 24 months.
Luoyang Xinzhaohe Standard vs. Common Market Quality
| Critical Parameter (Cu wire, 1.00 mm) | LXZH Spec | Typical Market | Test Method |
|---|---|---|---|
| Diameter tolerance | ±0.005 mm | ±0.010 mm | Laser gauge, ISO 3177 |
| Breakdown voltage (0.35 mm wall) | ≥ 4.5 kV rms | 3.0–3.5 kV rms | IEC 60851-5, 20 °C |
| Pin-holes (30 m) | ≤ 2 | ≤ 5 | 3 kV spark |
| Elongation after enamel | ≥ 25 % | 18–22 % | ISO 6892-1 |
| Concentricity | ≥ 85 % | 70–75 % | 360° laser |
| Thermal shock 200 °C 30 min | 1×d, no crack | 2–3×d, micro-crack | IEC 60851-6 |
| Conductivity (Cu) | ≥ 100 % IACS | 97–99 % IACS | ASTM B193 |
| Lot traceability | Cast→Spool | Coil only | MES barcode |
Take-away for Transformer Builders
By integrating rod casting, fine-wire drawing and enameling under one 44 000 m² roof, Luoyang Xinzhaohe eliminates batch-to-batch variation and cuts logistic mark-up. You receive Class 155–220 winding wire that meets or exceeds IEC 60317, delivered in 4–15 days ex-works Luoyang at a landed cost typically 18–22 % below comparable Western stock—without the MOQ penalties.
Packaging & Global Logistics
Export Packaging & Logistics – Wire, Strip & Foil for 2-Wire Transformers
(Engineered for 30-day door-to-door delivery from Luoyang to any major port)
H3 1. Sea-Freight Risk Mapping for Transformer Conductors
| Failure Mode | Root Cause | XZH Counter-Measure | Verification |
|---|---|---|---|
| Salt-fog corrosion | Chloride ingress through PE film micro-holes | 0,08 mm VCI film + 5 g/m² desiccant | 1000 h ASTM B117 salt spray, < 2 % weight gain |
| Coil collapse | Strap creep under 3 g stack load | 7-ply fumigated pine pallet, 3-direction strapping, corner boards | Compression test 6 t, deflection ≤ 5 mm |
| Enamel micro-cracking | Vibration resonance 15–60 Hz | Spool radial foam pad (Shore A 35) + pallet anti-slip mats | 8 h random PSD 0,2 g²/Hz, 5–200 Hz (ISTA-3E) |
| Condensation | 30 °C day / 10 °C night swing | 2-stage barrier: Alu-foil liner + silica gel (RH indicator card) | RH < 40 % after 45 days sealed |
H3 2. Packaging Specification Matrix
| Product Form | Inner Reel | Intermediate | Outer Unit | Gross Weight | 20 ft FCL Qty |
|---|---|---|---|---|---|
| Round winding wire 0,2–5,0 mm | DIN 355 plastic spool, 50 N radial strength | Carton sleeve, batch # & thermal class tag | Fumigated pallet 1,2 × 0,8 m, 4-way entry | 450 kg max | 22 pallets ≈ 9,9 t |
| Rectangular strip 3–12 mm × 0,8–3 mm | ID 300 mm steel reel, edges chamfered | VCI bag, end-cap locking | Same pallet, 1 vertical row, corner board | 500 kg max | 20 pallets ≈ 10 t |
| Foil roll 0,1–0,6 mm × ≤ 650 mm | ID 76 / 152 mm Al core, tension wrap | Foam spacer, Alu-foil barrier | Horizontal pallet, top deck sheet | 300 kg max | 24 pallets ≈ 7,2 t |
All pallets are ISPM-15 heat-treated; stowage compatible with 40 ft HC reefer or dry container.
H3 3. Luoyang Hub – Factory to Port Lead-Times
| Milestone | Transit Time | Carrier Options | Track & Trace |
|---|---|---|---|
| XZH plant → Zhengzhou rail hub | 2 h by truck (110 km) | COSCO, OOCL weekly block-train | GPS + RFID seal |
| Zhengzhou → Qingdao port | 24 h rail | 5 departures / week | EDI milestone auto-push |
| Qingdao → LA / Hamburg / Dubai | 11 / 23 / 14 days | CMA-CGM, MSC, Evergreen | Bills of lading same-day |
Cut-off: every Friday 18:00 CST; ETD Qingdao following Tuesday. Average door-to-door 18–28 calendar days to N. America / EU.
H3 4. Premium vs. Western Supplier Cost Snapshot
| Cost Driver | EU/US Mill | XZH China | Savings |
|---|---|---|---|
| Raw Al rod (LME + premium) | + 12 % | LME – 2 % | 14 % |
| Energy (annealing) | 0,18 $/kWh | 0,07 $/kWh | 9 % |
| Labor (fully loaded) | 28 $/h | 6 $/h | 7 % |
| Logistics (FOB port) | — | Inland 40 $/t | — |
| Total delivered $/kg | 9,80 | 7,10 | 27 % |
Price basis: 2 mm AIW 200 °C wire, May-2024 LME 2 350 $/t.
H3 5. Documentation & Compliance Pack
EN 60317-20 / IEC 60851 test certificates (breakdown ≥ 3 kV, elongation ≥ 25 %)
RoHS & REACH SVHC declaration, conflict-minerals free
China-origin Form-A / COO for preferential tariff (e.g., 0 % into ASEAN under RCEP)
MSDS for desiccant & VCI additive – non-hazardous cargo, no IMO restriction
H3 6. Quick-Start Sourcing Checklist for 2-Wire Transformer OEMs
- Confirm thermal class: 155 °C (Class F) is 18 % lighter than 180 °C (Class H) for same kVA.
- Quote wire + strip together; we can dual-schedule production, saving 1 week lead-time.
- Request 300 mm pilot spool for insertion loss check—air-sharged in 3 days.
- Book 3-month rolling forecast; we hold 50 t buffer stock, cutting your inventory carry by 30 %.
Contact: export@xzhal.com | WeChat: XZH-WIRE | Response < 12 h.
Sourcing from Luoyang Xinzhaohe
Why Partner with Luoyang Xinzhaohe for 2-Wire Transformer Windings
20-Year Metallurgical Track Record—Not Marketing Hype
Since 2003 we have supplied conductor rod, annealed wire and enamelled winding wire to Tier-1 transformer OEMs across 42 countries. Our Luoyang mill runs three dedicated lines for 2-wire (dual-voltage) transformer windings, processing 18 000 t/year of 99.85 % IACS-grade aluminum rod. Every coil is tracked from cast bar to spool via MES barcode; 100 % of production data is retained ≥10 years for failure-analysis traceability. That depth of history means we have already solved the thermal-shock, edge-crack and pin-hole issues that still plague younger suppliers.
Direct Factory Price—No Distributor Margin Stack
| Cost Element | Typical Western Distributor Channel | Luoyang Xinzhaohe Direct |
|---|---|---|
| Rod conversion margin | +8–10 % | 0 % |
| Regional warehouse markup | +6 % | 0 % |
| Stocking distributor | +12–15 % | 0 % |
| Total landed saving | — | 18–25 % |
We quote FOB Shanghai, CIF or DDP Harmonised-code 8544.11; wire price is linked to LME Al plus a fixed conversion fee locked for 12-month call-off orders. No hidden currency surcharges, no minimum-order penalties.
Customisation Without the Western “Engineering Fee”
Need 2.05 mm heavy-build polyester-imide overcoated with polyamide-imide for 180 °C (Class H) service? Or a 2-wire bundle with 0.200 mm wall and ±0.005 mm concentricity for 600 V / 120-240 V split-phase designs? We modify die geometry, enamel viscosity and inline laser eccentricity control in-house—lead time 10–12 days, no NRE. Below are typical 2-wire formats we ship every week:
| Specification | Standard Range | Tolerance Achieved | Inline Test |
|---|---|---|---|
| Diameter | 0.80 – 5.00 mm | ±0.010 mm | Laser micrometer, 4 kHz |
| Insulation wall | 0.06 – 0.25 mm | ±0.005 mm | Spark test 6 kV, 100 % |
| Elongation | ≥20 % (H12) – ≥35 % (O) | ±2 % | 250 mm gauge, ISO 6892 |
| Breakdown voltage | 4 kV – 12 kV | 6 σ ≥ 8 kV | VDE 0373, 500 V/s ramp |
| Thermal class | 130 °C (B) – 220 °C (C) | — | 2 000 h ageing per IEC 60172 |
All wire is spooled on 500 mm or 630 mm P5 plastic reels with tapered barrel to prevent collapse during high-speed automated layer winding. Custom flange colours, bar-coding and length pre-setting (±0.5 %) are available ex-factory.
Quality Systems Aligned to Your PQSR Audits
ISO 9001:2015, ISO 14001:2015, IATF 16949 rod line
UL Recognised Component (E332831) for 180 °C & 200 °C systems
REACH & RoHS II compliant, SVHC <0.1 %
CPRI (India) & KEMA (Netherlands) test reports on file
We host remote Teams audits and provide PPAP Level-3 within 5 working days—critical for 2 kVA – 75 kVA distribution transformer builds where UL, CSA or CE dossiers are mandatory.
Logistics Engineered for 4–15 Day JIT Programs
Luoyang is 1 h from Zhengzhou airport, 4 h from Qingdao port. Weekly consolidation to Rotterdam, Houston, Dubai and Chennai cuts average transit 7 days versus Shanghai-origin cargo. We maintain 320 t safety stock of 2-wire sizes 1.0 mm – 3.0 mm; EDI release schedules can be updated until 48 h before vessel cut-off.
Next Step—Request the 2-Wire Datasheet Pack
E-mail cathy@transformerstrip.com with your target kVA, thermal class and preferred spool size. We will return:
1. Technical datasheet (PDF + editable Excel)
2. UL / CPRI test certificates
3. 12-month price matrix
4. 10 kg trial-spool proposal (lead time 7 days)
Stop paying Western margins for Asian metal—partner with the factory that actually draws, anneals and enamels the wire.
📉 Import Savings Calculator
Estimate cost reduction by sourcing 2 wire transformer from Luoyang Xinzhaohe.