Engineering Reference Case Profile · Telecom & Power Cabinet Cooling
Telecom Cabinets, Power Cabinets and Inverter Stations · 48 V DC and EC Fans Under a Hard Power Budget
Compiled from LONGWELL’s real correspondence with telecom equipment makers, industrial power-cabinet builders and PV plant operators in Vietnam, Russia, Iran, Australia and the Philippines. Cabinet cooling is unusual in HVAC: the buyer usually names a power ceiling before naming an airflow, the supply is a 48 V DC bus, and the fan has to start reliably at −25 °C in an unheated outdoor enclosure.
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
- Power is the specification, airflow is the target. One telecom tender asked for 4,000 m³/h at under 290 W on a 48 V DC bus — a constraint that no catalogue selection satisfies at full speed.
- Outdoor cabinets are unheated. Russian nationwide deployments called for reliable start and run at −25 °C to −30 °C, with motor protection against locked rotor, reverse polarity and over-voltage, plus soft start.
- Life is quoted as a number. Cabinet buyers ask for MTBF and operating hours — 40,000 hours minimum on one programme — not a general reliability claim.
- Cross-reference work is 4-wire work. Replacing incumbent European and Japanese cabinet fans means pinning down whether the speed signal is PWM or 0–10 V and whether the fourth wire is FG (tacho) or an alarm output, before a sample is built.
- Inverter stations are the same problem outdoors at higher pressure. A PV container inverter station needed a like-for-like replacement at 3,863 m³/h against 1,133 Pa, at IP55, driven from the inverter cabinet’s own 0–10 V output.
- Neutral supply and custom labels are routine, since the fan sits inside a branded cabinet.
2 · Solution architecture
Selection starts from the power budget and the bus voltage, then works outward to airflow. Where the requested airflow and the power ceiling are in conflict, LONGWELL measures the fan de-rated to the customer’s power limit and issues the real airflow at that point, rather than declining the enquiry or pushing a higher-power model. The 48 V DC LWBD3G and LWBA ranges cover cabinet positions; the LWBE3G EC range covers high-pressure inverter and power-station duty.
Selections supplied into cabinet and inverter cooling
| Model | Ratings | Control & protection | Position |
|---|---|---|---|
| LWBD3G400-102NH-04 | 48 V DC, 480 W rated, 4,120 m³/h max; measured ≈3,900 m³/h when de-rated to 290 W | PWM or 0–10 V | Telecom cabinet, high airflow under a power cap |
| LWBD3G400-102NH-05 | 48 V DC, 279 W, 3,605 m³/h | PWM or 0–10 V | Telecom cabinet, inside a 290 W budget |
| LWBA175-EO | 48 V DC, 1.5 A, 75 W, 3,900 rpm, 620 m³/h, 440 Pa | PWM / 0–10 V | Compact power and telecom cabinets |
| LWBA220-EO | 48 V DC, 2.7 A, 130 W, 3,100 rpm, 1,050 m³/h, 540 Pa | PWM / 0–10 V | Power cabinets and enclosure exhaust |
| LWBA220-2E | 230 V / 50 Hz, Ø220 mm, motor range −40 to +80 °C | AC | Outdoor telecom cabinets on mains supply |
| LWBD175-EO / LWBD3G175-072NH-03 | 48 V DC (41–57 V), Ø175 mm, ≥40,000 h | PWM & 0–10 V input; locked-rotor, reverse-polarity, over-voltage protection and soft start; IP44 | Outdoor cabinets in severe cold |
| LWBD3G225-092NH-05 | EC Ø225 mm, 4-wire | PWM or 0–10 V with FG feedback | Cross-reference replacement in cabinets |
| LWAD12038HX-01 | DC 120×120×38 mm, 4-wire | PWM with FG | Small cabinet and rack positions |
| LWAE6D800S-5MKB-04 (LWAA6D800S) | 3-phase AC Ø800 mm axial | — | Large cabinet room and shelter ventilation |
| LWBE3G280-102PS-04 | 230 V, 50/60 Hz, 700 W, 3.1 A, 3,270 rpm, 3,863 m³/h, up to 1,658 Pa max static, 85 dBA | 0–10 V / PWM / RS485; over-temp, over-current and stall protection; IP55 | PV container inverter stations |
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.
Hard power ceiling met
≈3,900 m³/h at 290 W
LWBD3G400-102NH-04 measured de-rated, not extrapolated
Alternative inside budget
3,605 m³/h at 279 W
LWBD3G400-102NH-05, no de-rating needed
Cold-start range confirmed
−30 °C to +60 °C
Standard for the centrifugal range; tested to −25 °C to +80 °C
Life requirement met
≥40,000 h
Operating-hours requirement on the outdoor cabinet programme
DC bus range
48 V DC (41–57 V)
With PWM and 0–10 V control input
Inverter-station duty
3,863 m³/h @ 1,133 Pa
LWBE3G280-102PS-04, IP55, 700 W, 3,270 rpm
Motor protection set
Locked rotor · reverse polarity · over-voltage · soft start
Specified explicitly by cabinet buyers
Enclosure rating
IP44 / IP55
By position — sheltered cabinet versus outdoor container
4 · How these programmes run
Power budget confirmedThe power ceiling and bus voltage are established first. In this segment they are non-negotiable, and they determine whether the requested airflow is achievable at all.
De-rated measurementWhere airflow and power conflict, the candidate fan is measured at the customer’s power limit and the real airflow at that point is issued — with the recommendation to confirm against the actual cabinet resistance.
Cold and protection reviewMinimum ambient, start behaviour, IP class and the motor protection set (locked rotor, reverse polarity, over-voltage, soft start) are confirmed and documented.
4-wire definitionFor cross-reference work, the speed signal type (PWM or 0–10 V) and the fourth wire (FG tacho or alarm) are pinned down before samples are built.
Sample and test reportSamples ship with a factory test report; for first-time industrial customers, vendor registration documents are prepared in parallel.
Series supplyCustom labels and neutral packaging as required, since the fan ships inside the customer’s own branded cabinet.
5 · Engineering lessons carried forward
- When the requested airflow and the power ceiling contradict each other, do not decline and do not push a bigger fan. Measure the candidate de-rated to the customer’s power limit, publish the airflow at that point, and let them test it against their real cabinet resistance.
- For high-latitude outdoor cabinets, state the minimum ambient and the motor protection set up front. Buyers in this segment are sensitive to cold start, and leaving those fields off the specification simply extends the technical review.
- On a 4-wire cross-reference, confirm the speed-signal type and the meaning of the fourth wire before making samples. Getting this wrong means a completed sample fails on the bench for a reason that has nothing to do with the aerodynamics.
- MTBF and operating hours are treated as hard requirements here. Have the figure, the dynamic balance data and the test report ready with the first proposal.
- For first-time industrial customers, vendor registration and a factory test report are as much a part of sample approval as the fan itself — prepare them alongside the sample, not afterwards.
- PV inverter stations behave like outdoor telecom cabinets at higher static pressure. Where the incumbent model has no obtainable datasheet, work back from a sibling model plus the real application to reconstruct the duty point.
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, brand artwork, 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 and rounded to a band, in the currency as invoiced; many threads on this page are sampling or qualification stages, where the recorded value is a sample order rather than the series volume. Unit prices are never published.
Telecom cabinet cooling under a hard 290 W ceiling
- Requirement: 48 V DC backward-curved centrifugal, 4,000 m³/h with power below 290 W, PWM (or 0–10 V) speed control, target volume 5,000 pcs.
- The obvious selection, LWBD3G400-102NH-04, is rated 480 W with 4,120 m³/h maximum — over budget at full speed. Engineering measured it de-rated to 290 W and recorded ≈3,900 m³/h at that point.
- Two alternatives were offered alongside: LWBD3G400-102NH-05 (279 W, 3,605 m³/h) and a custom LWBD3G400-102NH-06 built to 290 W, with the recommendation to select on the cabinet’s actual resistance rather than free-delivery figures.
Nationwide outdoor cabinets in severe cold
- Two duties: a Ø220 mm AC fan at 230 V/50 Hz with a motor temperature range of −40 to +80 °C and one-year warranty; and a Ø175 mm 48 V DC fan (41–57 V) with PWM and 0–10 V control and at least 40,000 operating hours.
- The customer’s concern was reliable operation at −20 °C to −30 °C. LONGWELL confirmed the standard centrifugal envelope of −30 °C to +60 °C, with testing to −25 °C to +80 °C, and completed the specification with IP44, locked-rotor, reverse-polarity and over-voltage protection, soft start, dynamic balance data and the 40,000 h MTBF figure.
- The photograph below is from this programme: a Ø455 mm backward-curved fan on a panel with inlet ring, built for a three-phase and 48 V DC cabinet evaluation.
Cabinet fan cross-reference — 4-wire signals settled first
- Cross-reference of five incumbent models: a three-phase Ø800 mm AC axial, two 120 mm 4-wire DC axials, a Ø175 mm 4-wire DC blower and a Ø225 mm 4-wire EC centrifugal.
- Matched with LWAA6D800S-5MKB-04, LWAD12038HX-01, LWBD3G175-072NH-03 and LWBD3G225-092NH-05, with custom labels and neutral packaging.
- The controlling detail was the 4-wire definition — PWM versus 0–10 V, and whether the fourth wire was FG tacho feedback or an alarm output. This was confirmed with the customer’s engineering team before samples were made.
PV container inverter station — like-for-like at IP55
- Target duty read off the incumbent: 230 V, 50/60 Hz, 700 W, 3.1 A, 3,863 m³/h, 1,133 Pa, 3,270 rpm, 85 dBA, IP55.
- Matched with LWBE3G280-102PS-04 EC plug fan, which reaches 3,863 m³/h and up to 1,658 Pa maximum static, driven directly from the inverter cabinet’s 0–10 V output, with over-temperature, over-current and stall protection at IP55.
- Where the exact incumbent variant had no obtainable datasheet, a sibling model in the same series was used as the baseline and cross-checked against the container application.
Inverter cooling replacement into series supply
- Follow-on from the container evaluation: the same LWBE3G280-102PS-04 selection confirmed against the inverter’s sealed duct resistance at 3,863 m³/h and 1,133 Pa, and supplied as the replacement cooling fan.
48 V DC power-cabinet fans with test report and vendor registration
- LWBA175-EO (48 V DC, 1.5 A, 75 W, 3,900 rpm, 620 m³/h, 440 Pa) and LWBA220-EO (48 V DC, 2.7 A, 130 W, 3,100 rpm, 1,050 m³/h, 540 Pa).
- A factory test report was issued with the samples, and LONGWELL was registered in the customer’s overseas vendor system in parallel — on this account, vendor code setup and the test report were as much a gate as the fan performance.
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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