550mm AC Axial Fan for Condenser Units: 6,695 m3/h Case Study

What the condenser OEM needed

A European OEM was standardizing a new chassis for outdoor commercial condensers and needed an AC axial fan to suit it. The airflow target was 6,695 m3/h.

The brief was direct. Furthermore, the constraints left very little room.

• A 550mm blade diameter, and total assembly depth under 190mm.
• 230 VAC single phase at 50Hz.
• Reliable running from -30C to +60C, since the units ship to very different climates.
• No more than 65 dB(A) at the main operating point, because these sit near commercial and residential property.
• IP54, since these units live outdoors in dust and spray.
• Full CE certification, especially against EN 60335-1.
• Performance validated to ISO 5801, so their engineers can model the system properly.

Here the temperature span is the demanding part. An AC axial fan that starts happily at -30C and still runs at +60C places two quite different demands on the same bearing grease and the same insulation.

Specifying the AC axial fan

Two decisions shaped this fan. Firstly the motor technology, then the blade count.

Why we recommended against EC

We considered an EC motor for its efficiency, then rejected it. The reason lies in the control system rather than the motor.

At this product tier the customer switches fans simply on and off, and the application never asks for variable speed. Fitting an EC fan would have raised the bill of materials by roughly 30% while delivering nothing the end user could use. Consequently we specified a 6-pole AC external rotor motor, a design with a long record in continuous S1 duty.

Five blades rather than seven

We modeled a seven-blade impeller first, mainly to see what it did acoustically. However, CFD showed a five-blade wheel gave a better balance of airflow, pressure and efficiency at the target 900 RPM.

That result is not obvious. More blades usually means quieter running at a given speed, yet they also cost airflow and draw more power. At 900 RPM, therefore, the five-blade wheel lands better on all three counts.

Steel rather than polymer

The blades are cold-rolled steel. Polymer alternatives were available, and we did not choose them, since some plastics turn brittle towards the bottom of a -30C to +60C range. Steel, by contrast, behaves the same at both ends.

Protecting the motor

Class F insulation is rated to 155C, so at a +60C ambient there is a large margin in hand. In addition, an integrated thermal protector opens between 150 and 160C. That stops a blocked or stalled AC axial fan destroying its own windings.

Meanwhile the final model, LWAA6E550S-5MEB-05, delivers 6,695 m3/h at 62 dB(A) inside a 320W envelope. That is three decibels under the customer limit.

Technical Specifications

The noise figure below came in three decibels under the customer limit. That headroom is what lets an installer place these units nearer a boundary wall.

Technical Documentation

Here the comprehensive PDF datasheet contains all performance data, mechanical drawings, and wiring diagrams for the LWAA6E550S-5MEB-05, essential for design engineers. Download the PDF Spec Sheet.

The product overview image shows the LWAA6E550S-5MEB-05 assembly, including the 5-blade impeller and protective grille. It is useful for procurement managers to visually confirm the product configuration.

An editable DOCX version of the specification sheet is available for system integrators to incorporate data directly into their own technical documentation. Download the DOCX Spec Sheet.

Why the OEM changed supplier

Beyond the specification itself, three things carried the decision.

• A unit cost that reaches the product line. The same 6,695 m3/h, with IP54 protection and Class F insulation, built on our own lines from our own motor. On a product manufactured repeatedly, component cost is where profitability is decided.
• A faster route through CE. Our established relationship with a Ningbo-based TUV NORD notified body streamlined the EN 60335-1 testing and documentation, which shortened the customer normal certification window substantially.
• Test reports, not claims. The OEM received full reports from our in-house lab, independently verified to AMCA 210/211 and ISO 5801 methods. Naturally that included the P-Q curve their simulation needed.

Browse our AC axial fan range, or the condenser fan series for refrigeration duty. Protection ratings are defined in IEC 60529.

Questions specifiers ask

What L10 life does it have, and what bearings?

It is calculated at 30,000 hours L10 when running at 20C and 15 to 65% relative humidity. The bearings are maintenance-free deep groove ball type, chosen to hold their performance across the full -30C to +60C range rather than only at room temperature.

Can I control its speed with a VFD?

No. This AC axial fan uses a shaded-pole motor and is not designed for drive control. A VFD will make it hum, run hot and eventually fail. Where you need variable speed, take an EC axial fan instead, with SmartEC control for 0-10V, PWM or Modbus RS485.

Does IP54 cover the terminal box as well?

Yes, the rating applies to the complete assembly. The external rotor motor is fully encapsulated and the electrical connections sit inside a sealed junction box. The whole unit is tested against dust ingress and water spray from any direction, per IEC 60529.

Why does blade count change the noise?

Every blade passing the housing sends out a pressure pulse, and the rate of those pulses is the tone you hear. Changing blade count moves that frequency and changes how much energy goes into it. Consequently blade count is an acoustic decision as much as an aerodynamic one.