Trox X-Fans GmbH uses ABB’s ACH580 variable speed drives, also known as frequency converters, in its speed-controlled smoke extraction fans. The ACH580’s override mode enables safe evacuation in the event of a fire and ensures continued operation of the smoke extraction system, even under extreme conditions.
While smoke extraction systems were previously operated almost exclusively via a fixed mains connection, the use of frequency converters has changed this approach. To ensure reliable fan start-up, it is essential to avoid overloading the power grid. By limiting the starting current, frequency converters reduce grid load while also minimizing mechanical stress on fan components. In addition, demand-based speed control enables energy-efficient operation.
The correct operating point
Oliver Holstein, Head of Sales at Trox X-Fans, explains: “Frequency converters have been used in ventilation technology for many years, and we have made them a key focus of our work. Particularly in complex smoke extraction duct systems, deviations in operating points can occur — for example, in multi-zone smoke extraction systems where one extraction fan serves several smoke compartments. In such situations, a frequency converter makes it easy to set the correct operating point.”
The company has been working with ABB for around 15 years. ACH580 frequency converters, specifically designed for ventilation and building technology, are used to adjust the air volume flow as required. “The converter’s ease of use and the excellent technical support convinced us. We knew that using frequency converters in conjunction with smoke extraction fans was a challenging but viable solution. ABB is the right partner for this,” says Oliver Holstein.
Users particularly appreciate the intuitive display operation and PC-based parameterization. The HVAC frequency converters’ dedicated firmware is specifically tailored for use with Trox X-Fans products, enabling easy adjustment of relevant parameters. ABB converters are used with motor outputs ranging from 0.5 kW to 430 kW.
The smoke extraction system serves as ventilation
Trox X-Fans have implemented numerous projects using ABB frequency converters. For example, smoke extraction fans were integrated into the building design of a new publishing house in Berlin. The company supplied ten BVAXN 12/56-1250 DAX smoke extraction fans for the main building, each controlled by an ACH580. The fans and frequency converters each have a power output of 37 kW.
A special feature of the project is the dual use of the smoke extraction system for both daily ventilation and emergencies. The required operation with adjustable airflow is achieved via frequency converters.
Examination as a complete unit
Smoke extraction fans must be tested in accordance with DIN EN 12101-3, “Smoke and heat control – Part 3”. This standard defines the product characteristics of power-driven smoke and heat exhaust ventilators used as components in mechanical smoke and heat exhaust systems. A prerequisite for approval is fire testing of the complete system, consisting of the fan and the frequency converter. Since 2012, Trox X-Fans has had these tests carried out by the Materials Testing Institute for Civil Engineering in Braunschweig. As a result, a wide range of tested fans with frequency converters in temperature classes F300 to F600 is available.
Regarding the requirements for the drive technology, Oliver Holstein explains: “In an emergency, the smoke extraction fan and the frequency converter must work together seamlessly. Neither can fail — both must operate for as long as possible. The tests have shown that this is achievable.” The frequency converter must reliably control the motor running even at test temperatures of 300 °C or 600 °C.
Override mode for emergency situations
A key feature of the ACH580 is its override mode, designed specifically for smoke extraction operation. If the smoke extraction function is activated in the event of a fire, internal fault monitoring is disabled within the frequency converter. This allows the frequency converter and motor unit to continue operating until failure, thereby extending fan runtime in emergency situations and supporting evacuation. Frequency converters with an override function enable seamless switching between normal and override operation. This makes it possible to perform test runs without requiring a manual reset. In override mode, different speeds can be preset and airflow adjusted to suit the specific situation. Reversing the direction of rotation is also possible, providing additional flexibility for smoke extraction and evacuation strategies.*
* Best suited for bi-directional fan units, such as dual inlet/dual outlet designs or fans with adjustable blade angles. In uni-directional fans, this approach may result in reduced efficiency, decreased airflow/pressure, and higher noise levels.
