To date, typical uses for modern EC fans have mainly included applications involving continuous operation, such as ventilation and air conditioning. For some time now, users have benefited from high efficiency, economical energy consumption and the associated low operating costs, plus low noise generation. However, there are many applications that require the fans involved to get up to speed more rapidly. AC fans were typically used in these applications, but since 2015 they often no longer meet the applicable requirements of the ErP Directive (ecodesign directive). For these applications, there is now an alternative that complies with the ErP directive: energy-efficient EC centrifugal blowers that not only start up rapidly but also offer other benefits.
The classical ventilation and air conditioning applications do not necessarily rely on rapid start-up. Instead, soft-start functions – a gentle, hardly perceptible start – are in demand. But this does not mean that EC fans cannot start up rapidly. If the control electronics are optimized for a steeper ramp-up curve, even EC motors can get up to speed within a very short time (Figure 1). For example air locks, including the ones before clean rooms in electronics production and air curtains in truck loading docks, are an application that requires rapid start-up of fans (Figure 2). But centrifugal blowers are also used in cooling systems, power electronics and kitchen exhaust hoods.
High air performance + low power consumption
ebm-papst Mulfingen, the motor and fan specialist, has developed a new line of EC centrifugal blowers (Figure 3). They get up to speed at least as fast as the usual AC variants, but are considerably more energy efficient and function more quietly. The “heart” of these brisk high performers is a GreenTech EC motor with an output of 0.75 kW, with a size range of 160-250. Despite their compact size, the centrifugal blowers can achieve airflows of up to about 3,000 m³/h in start-up times of only 3-4 s. And they consume much less power than AC fans do. Depending on the application, energy savings of well over 30% are possible with these centrifugal blowers. Despite their rapid start-up, they generate a low level of noise. They have a large number of forward-curved impeller blades, which is partly responsible for this property and ensures that the psychoacoustics are pleasant – especially in the low-frequency range.
Depending on the application, energy savings of well over 30% are possible.
Due to their high air performance (Figure 4), EC centrifugal blowers are also suitable for the high air curtains at large factory gates. Additional design details reinforce this effect. For example, the motor electronics are not attached directly to the motor, but instead to the outside of the scroll housing. This reduces the number of fittings that could obstruct the airflow. However, the electronics are cooled to the required extent: bumps on the bottom of the electronics housing (Figure 5) increase the power density and reliably prevent overheating. The electronics are also reliably protected against outside influences such as moisture or dust. Their housing is made of rugged die-cast aluminum that satisfies the requirements for the IP54 degree of protection.
Fans for air locks and air curtains are not “lone warriors” but instead are usually found in parallel connection. However, EC fans function in a way that has an impact on the grid. Operating several EC fans in parallel may cause the permissible limits stipulated in EN61000-3-2 to be exceeded and adversely affect other devices in the system network. Normally, operators must supply an interference suppression filter, ensure adequate power factor correction and be aware of the possible need for a larger cable cross-section.
The new EC centrifugal blowers eliminates the need for these precautions. Integrated active power factor correction (PFC) significantly reduces the harmonic content in input current (Figure 6). It also minimizes the peak input current values and in many applications, users can select a smaller cross-section cable for the fans’ power lines.
Regulation and monitoring as required
Another feature of EC motors is their control characteristics: practice-oriented control options are a matter of course with these modern fans. The control electronics are perfectly harmonized with the motors they contain and they are also infinitely adjustable. This is possible over the entire speed range and even retains the fans’ excellent efficiency in partial-load operation. Via a digital RS-485 MODBUS-RTU interface, the units can be controlled as required.
For maintenance, technicians are able to access the fans from a central computer.
Especially when several fans are in use – as is the case with air curtains – bus connection offers advantages in a range of situations, from configuration during commissioning and troubleshooting to service and maintenance. For error diagnosis and maintenance, it becomes much easier to handle the technology when technicians are able to access the fans from a central computer. Other than the relevant computer software, there is also a PDA- and smartphone-capable version that can be used to parameterize, monitor and remotely control the fans in the network via Bluetooth interface without a cable connection.
Uncomplicated installation and commissioning
A complete plug-and-play solution: The EC centrifugal blowers from ebm-papst can be put to work quickly and easily. The motor shaft can be positioned either horizontally or vertically, as required. All the components are designed to be highly robust and have long service lives. The blade and nozzle plate are made of galvanized sheet steel. A further argument in favor of these ErP-compliant, energy-saving centrifugal blowers cannot be overlooked: their development and production focuses on sustainability and resource preservation.