600V AC Axial Fan for Industrial HVAC: 500mm Case Study

What the North American OEM needed

A North American OEM asked for a 500mm AC axial fan running on 600 VAC. Their starting point was our existing LWAA4D500S-5MEB-20, with one critical change. Namely, it had to work on their 600V, 60Hz industrial grid.

Projected demand was 300 units a year. Furthermore, they wanted sample and production pricing together with drawings for integration.

Meanwhile the application is cooling for large stationary industrial equipment. Consequently IP54 protection and a -30C to +60C range were essential rather than optional, since this kit lives without much shelter.

• The envelope of a standard 500mm unit, since the existing design is fixed.
• A basket diameter of 538mm and 192mm depth, as the drawing shows.
• Roughly 8,369 m3/h, exactly matching the baseline model.
• No more than 75 dB(A), measured as before.
• Lastly, testing to ISO 5801, plus CE for the end market.

The came in as light development. Namely, adapting a proven design rather than starting from nothing.

Rewinding the AC axial fan for 600V

Here the task sounds simple, though it is not. Take a 380V fan and make it run on 600V, without changing a dimension or losing any airflow.

Why not a step-up transformer

We considered a standard 480V motor plus a transformer, then rejected it early. It adds a part, adds cost and size, and adds a failure point.

For an OEM trying to keep an integration clean, none of that is acceptable. The fan had to accept 600V natively.

Recalculating the winding

Therefore the work went into the stator winding of the external rotor motor.

Higher voltage needs more turns of finer wire. Consequently both figures needed recalculating precisely, since the magnetic flux and the torque must stay where they were. Otherwise the five-bladed impeller never reaches 1550 RPM, and the airflow collapses with it.

Checking the heat

Finer wire carries less current before it warms, so we verified the thermal behavior rather than assuming it.

Simulations showed the new winding runs safely inside its Class F limit of 155C, even at the full 600W input. The fan own airflow cools the motor, which helps considerably. Importantly, we counted that effect rather than treating it as spare margin.

What stayed the same

Maintenance-free deep groove ball bearings and the cold-rolled steel impeller carried over unchanged. Consequently the mechanical durability of the original survives intact.

The result, LWAA4D500S-5MYB-38-00, is a drop-in replacement that runs natively on 600V. Nothing else about the customer installation had to move.

Technical Specifications

Meanwhile the voltage row is the only line that changed from the base model. Otherwise everything below carries over unaltered on this AC axial fan, which was the object of the exercise.

Technical Documentation

The final approved engineering datasheet contains all mechanical dimensions, electrical specifications, and the P-Q performance curve required by a system integrator. Download the full specification for LWAA4D500S-5MYB-38-00.

Here the image below shows the initial customer request as captured in Longwell’s project management system, representing the starting point for the engineering workflow.

Why the rewind happened here

At only 300 units a year, four things made a non-standard voltage practical.

• Drawings and a quote in days. The customer needed a specific 600V answer. Our engineering turned technical drawings and production-ready pricing around quickly for this light modification, against the far longer cycles European suppliers quote for the same request.
• We wind our own motors. Designing and producing a custom winding in house was the whole project. Relying on an external motor vendor would have added both cost and months to a job of this size.
• Almost no tooling cost. Adapting an existing high-volume 500mm AC axial fan platform kept NRE minimal, which is what makes a bespoke voltage viable at 300 units rather than 30,000.
• Compliance carried across. The base platform has an established CE and RoHS history, while all changes ran under our ISO 9001 system. Consequently the OEM gets documentation their own certification can rely on.

Browse our AC axial fan range, or the industrial axial fan series for larger frames. Insulation classes are defined by the IEC in IEC 60085.

Questions about custom voltages

What is the lead time on a custom voltage fan?

The first technical proposal came back in under a week, because this ran as light development. New production orders take 25 to 35 days at typical volumes. That is possible because the core fan components are standard stock, and only the winding process is specific to this build.

Is the 600V version UL certified?

Meanwhile the base series is designed to UL 507 and UL 1004-1 principles, though this particular 600V variant has no separate UL file. We supply the construction data, material specifications and test reports your final product certification needs. Where volume justifies it, a dedicated UL certification is available through our 90-day NPI service.

Can the performance be adjusted?

Not natively. On an AC axial fan the speed follows line frequency, giving a constant 1550 RPM and 8,369 m3/h at free air. An external VFD rated for the motor load will vary it, or we can propose a SmartEC alternative with 0-10V and PWM control built in for the same 600V supply.

Why does higher voltage need finer wire?

Because the motor needs a similar magnetic field either way, and field strength follows turns multiplied by current. Raising the voltage lets you use less current, so you compensate with more turns. More turns in the same slot means thinner wire. Consequently the thermal check becomes necessary.