380V AC Centrifugal Fan for HVAC: 695 Pa High-Pressure Case Study

What the ventilation OEM needed

A commercial ventilation OEM needed an AC centrifugal fan for a new line of air filtration units. One figure shaped everything. Namely 695 Pa of maximum static pressure.

The enquiry arrived with a photograph of a rival fan attached. That single detail tells you what this is. Basically a second-source project, where the new fan must swap in on both size and output.

Here the constraints were firm on every axis.

• 380V three-phase, since that is the standard supply on site.
• Compatibility with 50Hz and 60Hz grids, so one mechanical design serves North America and Europe.
• A 225mm impeller, with overall depth under 101mm to fit the existing chassis.
• Airflow above 1,200 m3/h, because dense filter banks resist heavily.
• An ambient range from -40C to +65C, at both ends.
• Lastly, CE certification, for market access.

That mix of high pressure and shallow depth is the awkward part. Pressure normally costs you size. Here, though, the size was already spent.

Matching the AC centrifugal fan to the duty

The turned out to be a catalog match rather than a development project. Consequently the customer saved both time and tooling cost.

AC rather than EC, for once by request

An AC motor suited the customer control setup, which never asks for variable speed. Choosing an AC centrifugal fan therefore kept the bill of materials and the wiring simple.

Where a customer does want efficiency and smart control, our SmartEC platform offers an equivalent fan. Here, however, it would add cost for something the system cannot use.

Why backward-curved

Meanwhile the LWBA2D225-092NT series uses a backward-curved wheel. That is the choice the pressure figure forces on you.

A forward-curved wheel simply cannot reach 695 Pa in this footprint. Backward-curved blades make high pressure efficiently, which is just what a dense filter bank demands.

Why the impeller is plastic

The impeller is glass-filled polyamide rather than stamped steel. PA66 gives high strength and good rust resistance at much lower spinning mass.

Lower mass has two practical effects. Firstly, start-up current falls. Secondly, the long-term load on the bearings drops with it. On a fan running all day, that second point is worth more than the first.

Two variants for two grids

We sent datasheets for both frequencies. The LWBA2D225-092NT-12 runs 60Hz at 2900 RPM, giving 1257 m3/h and 695 Pa. Meanwhile the LWBA2D225-092NT-11 runs 50Hz at 2600 RPM, giving 1133 m3/h and 546 Pa.

Both motors use Class F insulation with a built-in auto-reset thermal cut-out. That is what makes running at the top of a -40C to +65C range safe rather than merely possible.

Technical Specifications

Two AC centrifugal fan variants are listed below, one for 50Hz and one for 60Hz. Compare the speed rows first, since everything else follows from them.

Technical Documentation

Complete documentation was provided to the customer’s engineering team to accelerate their qualification and integration process. The following files are available for review.

Specification Sheet (LWBA2D225-092NT-12 / 60Hz): This PDF contains the full technical data, performance P-Q curve, and mechanical drawings for the 60Hz model, essential for system design engineers.

Specification Sheet (LWBA2D225-092NT-11 / 50Hz): This document provides the complete technical details for the 50Hz variant, required for teams designing equipment for the European and other 50Hz markets.

Product Overview Image: This image provides a quick visual reference of the fan, its performance characteristics, and key technical specifications.

Source File (60Hz Spec Sheet): The original Word document for the 60Hz specification sheet is available for integration into the customer’s internal documentation systems.

Source File (50Hz Spec Sheet): This Word document is the source file for the 50Hz fan specifications, provided for the customer’s convenience.

Why the second source came here

Choosing a fan supplier involves more than matching a spec sheet. In this case, four things counted.

• A lower landed cost. Making the parts ourselves in Ningbo puts this AC centrifugal fan well below matching European models, and nothing is given up on engineering or output.
• Lead times that move a launch. Standard make-to-order fans run 15 to 25 days here, whereas many European suppliers average 8 to 12 weeks. That gap is measured in launch dates.
• Curves that hold under test. Every specification sheet carries performance data independently verified to AMCA 210/211 and ISO 5801 methods, so an engineer can design to the number rather than around it.
• A route to further certifications. CE covered this project. For future UL or ATEX work, our relationship with a China-local TUV NORD notified body shortens the timeline considerably.

Browse our backward-curved centrifugal fan range, or the centrifugal fan section generally. Fan test methods are published by AMCA International.

Questions procurement teams ask

What separates the NT-11 from the NT-12?

Supply frequency, and everything that follows from it. The NT-12 is built for 60Hz grids and runs at 2900 RPM. The NT-11 suits 50Hz and runs at 2600 RPM. Consequently the 60Hz version delivers more airflow, 1257 against 1133 m3/h, and more pressure, 695 against 546 Pa.

Is there an EC version for variable speed?

Yes. We build a parallel line of backward-curved fans on SmartEC motors, alongside every AC centrifugal fan in this series, which give considerably better efficiency plus precise control through 0-10V, PWM or Modbus RS485. That suits demand-based ventilation and tighter energy rules such as ErP.

What protects the motor?

Class F insulation rated to 155C, plus an integrated auto-reset thermal protector. The protector opens the circuit between 150 and 160C and closes again once the windings cool to between 100 and 130C, so an overload or a hot day does not cause permanent damage.

What L10 life and bearings does it have?

It is specified at 40,000 hours L10 running continuously at a 40C ambient, on maintenance-free deep groove ball bearings. No periodic lubrication is needed, which removes a recurring service cost from the end user.