Engineering Reference Case Profile · Transformer & Power Equipment Cooling
Dry-Type Transformer Forced-Air Cooling · Cross-Flow Assemblies, Mounting Beams and EC Upgrades
Compiled from LONGWELL’s real correspondence with dry-type transformer, AVR and high-voltage equipment manufacturers. What this segment buys is rarely a bare fan: it is a cooling assembly — cross-flow fans on a purpose-made mounting beam, with a junction box, guide vanes and cable that meet the customer’s own standard, qualified for storage and transport down to −60 °C.
About this case profile: This profile is compiled from real LONGWELL project correspondence in this segment. Customer names, commercial terms and pricing are withheld; company names and branding have been removed from the photographs. Model numbers, electrical ratings and dimensions are quoted from LONGWELL controlled datasheets, product nameplates and customer-approved drawings. Where a figure is a typical range rather than a measured project result it is labelled as such. Named references are available under NDA on project qualification (sales@longwellfans.com).
1 · Challenge
- The transformer manufacturer specifies airflow with a power ceiling, not a fan model: for example VS400 — not less than 200 m³/h at not more than 43 W, within an envelope of 325 × 105 × 95 mm. Every size in the range comes with its own envelope.
- The deliverable is an assembly: fans mounted on an aluminium or steel beam, with a junction box, adjustable guide vanes and cable to the customer’s national standard — not loose fans that they then have to integrate.
- Climate qualification is severe. One specification required survival through −60 °C to +55 °C storage and transport, which drives motor grease, plastic components and cable jacket material.
- Forced-air cooling of a transformer runs against real duct and fin resistance, so these customers work from P–Q curves, not maximum airflow figures — they need the fan curve to overlay onto their own resistance calculation.
- On cross-flow impellers for this duty, the rubber bearing sleeve must be fixed on the shaft with zero axial movement. Long-term vibration and thermal cycling on a transformer will find any float and turn it into noise or failure.
- Nothing goes to volume without a customer-signed and stamped engineering drawing; assembly tolerances and bearing positioning are dimensioned on it.
- Cross-flow impellers are light and stack tall on a pallet. They deform under load, so stacking rules have to be issued in writing before sea freight.
2 · Solution architecture
This segment is served as a cooling assembly programme. LONGWELL supplies the cross-flow fans (AC and BLDC), and develops the mounting beam, guide vanes and junction box against the customer’s own technical specification, so the transformer builder receives a bolt-on cooling module. For higher static pressure positions — enclosed cabinets, high-voltage switchgear, AVR units — the LWBE3G backward-curved EC range and the DD series AC double-inlet blowers cover the same duty with 0–10 V speed control or fixed speed.
Selections supplied into transformer and power equipment cooling
| Model / item | Duty and ratings | Environment / control | Position |
|---|---|---|---|
| LWCA-60240S-10 / LWCA-60300S-10 | Ø60 mm AC cross-flow, 240 / 300 mm barrels | −60 to +55 °C storage and transport | Dry-type transformer forced-air cooling |
| LWCA-60240SN-01 / LWCA-60300SN-01 | Ø60 mm cross-flow, alternative build | Guide vanes at the discharge | Dry-type transformer forced-air cooling |
| Customer-spec mounting beam assembly | Aluminium or steel beam with junction box | Flame-retardant cable to national standard | Bolt-on cooling module for the transformer core |
| Ø80 mm aluminium cross-flow impellers | 80 × 175 / 80 × 355 / 80 × 495 mm | Rubber bearing sleeve fixed on shaft, zero axial float | Transformer cooling equipment builders |
| Ø80 mm plastic cross-flow impellers | Same three lengths | Alternative to aluminium on cost and noise | Transformer cooling equipment builders |
| LWBE3G250-092NS-12 (EC centrifugal) | 230 VAC (176–264 V), 50/60 Hz, 140 W, 0.61 A, 3,010 rpm, 1,531 m³/h (911 CFM), 785 Pa, 72.1 dB(A) | IP44, Class B (130 °C), −25 to +60 °C, 0–10 VDC | High-voltage equipment and transformer cabinets |
| LWBA2E190-072NS-01 (AC centrifugal) | 230 VAC (165–254 V), 50 Hz, 56 W, 0.25 A, 2,640 rpm, 483 m³/h | Fixed speed | Compact cabinet cooling |
| DD series AC double-inlet blowers | DD7-7 90 W 6P (850 rpm, 0.9 A) · DD7-7 200 W 4P (1,150 rpm, 1.8 A) · DD9-9 550 W 4P (1,150 rpm, 4.6 A) | 230 V / 220 V 50 Hz, direct drive | Transformer cooling equipment, forced-draught positions |
3 · Verified figures
Fan performance figures are quoted from LONGWELL controlled datasheets and product nameplates and are tested per AMCA 210/211 methods; third-party reports available on request. EC versus AC energy saving is approximately 30%, higher under strongly varying load — confirm against your own load profile. Final selection must be confirmed against the actual duty point (airflow, static pressure, ambient temperature, certification scope) of your machine.
Climate qualification
−60 to +55 °C
Storage and transport requirement — drives grease, plastics and cable jacket
Specified duty example
≥200 m³/h at ≤43 W
VS400 size, inside a 325 × 105 × 95 mm envelope
Largest size in the same range
≥800 m³/h at ≤95 W
VS1800 size, 510 × 129 × 129 mm envelope
Ø80 mm impeller lengths
175 / 355 / 495 mm
Aluminium and plastic, both sampled before the customer chose aluminium
Bearing sleeve requirement
Zero axial float
Rubber bearing sleeve fixed on shaft — a written, drawing-level requirement
EC cabinet selection
785 Pa at 140 W
LWBE3G250-092NS-12, 1,531 m³/h (911 CFM), 3,010 rpm, IP44, 0–10 VDC
Assembly content
Beam + junction box + guide vanes
What this segment actually orders, rather than loose fans
Release condition
Signed and stamped drawing
No volume production before customer sign-off on the engineering drawing
4 · How these programmes run
Specification receivedThe customer sends a size table stated as airflow with a power ceiling and a dimensional envelope, referenced to their own technical standard document.
Assembly scope confirmedFirst question back: is a mounting beam, junction box and guide vane assembly required? In this segment the answer is usually yes, and it changes the whole scope.
Climate and materials reviewLow-temperature storage and transport requirements are checked against motor grease, plastic components and cable jacket material before anything is quoted.
P–Q curves issuedFan curves and CAD dimension drawings are sent with the first proposal so the customer can overlay them on their own fin and duct resistance calculation.
Sampling and drawing sign-offAluminium and plastic impeller options are sampled where relevant. Engineering drawings dimension the bearing sleeve position and anti-float requirement, and are signed and stamped by the customer before volume.
Production and despatchStacking guidance is issued in writing — cross-flow impeller pallets are light and must not be loaded from above. Combined orders ship with a consolidated packing list and matched documents.
5 · Engineering lessons carried forward
- Ask whether the customer wants fans or a cooling assembly. Transformer builders routinely need the beam, junction box and guide vanes as one deliverable. Establishing that at the first exchange, rather than after quoting bare fans, is the difference between a component enquiry and a system order.
- Verify extreme storage temperature against materials, not just the motor rating. A −60 °C storage and transport requirement affects grease, plastic parts and cable jacket — components that never appear on a fan performance datasheet.
- Send the P–Q curve and the CAD drawing with the first proposal. These customers size against their own fin and duct resistance; a maximum airflow figure alone cannot be used and simply generates another round of questions.
- Dimension the bearing sleeve position and the anti-float requirement on the drawing. On a transformer, long-term vibration and thermal cycling will find any axial play and turn it into noise or bearing failure — and get the drawing signed and stamped before volume.
- Issue stacking guidance in writing. Cross-flow impellers are light and pallet tall; they deform under load. They can be stacked on top of heavier goods but must never be loaded from above.
- Keep bank details unchanged across proformas for large corporate accounts. On one high-voltage equipment account any variation in the payment account triggered a compliance review and delayed both payment and the production slot.
6 · Project evidence
Every item below is a real project thread from LONGWELL’s own correspondence. Each carries an anonymised case reference, the counterparty described by industry and buying role only, an evidence grade, the actual dates from first contact to close, the length of the email thread and, where an invoice is on file, the order value band. Customer names, domains, prices and commercial terms are withheld — including from the photographs. Evidence grade A means controlled documents or test reports are on file for that thread; grade B means a structured enquiry and specification are on file. Order value bands are read from the proforma or commercial invoice held on file for that thread and are rounded to a band; the invoice currency is shown as invoiced. A band is only given where the invoice currency is unambiguous — 20 of the threads on these pages carry one. Unit prices are never published.
Dry-type transformer forced-air cooling as a complete assembly
- Specification stated as airflow with a power ceiling per size: VS400 ≥200 m³/h at ≤43 W (325 × 105 × 95 mm); VS600 ≥240 m³/h at ≤48 W (385 × 105 × 95 mm); VS1200 ≥460 m³/h at ≤75 W (330 × 129 × 129 mm); VS1800 ≥800 m³/h at ≤95 W (510 × 129 × 129 mm).
- Supplied as custom AC and BLDC cross-flow fans (LWCA-60240S-10, LWCA-60300S-10, LWCA-60240SN-01, LWCA-60300SN-01) developed against the customer’s own technical specification document, together with the transformer mounting beam, airflow guide vanes and junction box.
- Qualified for −60 °C to +55 °C storage and transport, with flame-retardant cable and terminations to the customer’s national standard. The mounting beams below are from this programme.
Ø80 mm impellers — aluminium chosen after physical testing
- Aluminium and engineering-plastic Ø80 mm cross-flow impellers sampled in three lengths — 80 × 175, 80 × 355 and 80 × 495 mm, each with a rubber-mounted ball bearing.
- After testing, the customer selected aluminium for its higher structural stiffness and better temperature performance.
- The controlling requirement was written into the drawing: the rubber bearing sleeve must be fixed on the shaft with no axial movement. Engineering issued dimensioned drawings marking the sleeve position and retention, signed and stamped by the customer before trial volume.
- Stacking guidance was issued with the shipment — the impeller pallets are light and tall and must not be loaded from above, though they may sit on top of heavier cargo. Two orders were consolidated with a merged packing list and matched documents.
EC and AC centrifugal selection for high-voltage equipment
- LWBE3G250-092NS-12 single-inlet backward-curved EC: 230 VAC (176–264 V), 50/60 Hz, 140 W, 0.61 A, 3,010 rpm, 1,531 m³/h (911 CFM), 785 Pa, 72.1 dB(A), IP44, insulation Class B (130 °C), −25 to +60 °C, 0–10 VDC speed control.
- Datasheets for LWBA2E190-072NS-01 (230 VAC, 56 W, 0.25 A, 2,640 rpm, 483 m³/h) and LWBE3G355-102NS-15 were supplied in parallel for their wider cooling platform.
- Delivered inside the 25–30 day window required to meet the customer’s month-end production schedule.
DD series AC blowers with full P–Q curve set
- DD series direct-drive double-inlet forward-curved blowers from 7″ to 12″: DD7-7 90 W 6P (850 rpm, 0.9 A, 230 V/50 Hz), DD7-7 200 W 4P (1,150 rpm, 1.8 A), DD8-8 200 W 6P (820 rpm), DD9-9 375 W 6P (850 rpm, 3.5 A), DD9-9 550 W 4P (1,150 rpm, 4.6 A), DD10-10 450 W 6P (850 rpm), plus 650 mm and 750 mm industrial wall fans.
- The customer’s engineering department required the complete AC fan curve catalogue to overlay onto their transformer duct resistance calculation; the consolidated curve set was issued with the proposal.
AVR cooling selection
- Cooling fan selection for automatic voltage regulator units, based on the LWBA2E190-072NS series AC centrifugal platform.
Fan performance figures are quoted from LONGWELL controlled datasheets and product nameplates and are tested per AMCA 210/211 methods; third-party reports available on request. EC versus AC energy saving is approximately 30%, higher under strongly varying load — confirm against your own load profile. Final selection must be confirmed against the actual duty point (airflow, static pressure, ambient temperature, certification scope) of your machine.
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