Figure 1: The new EC centrifugal blowers start up just as rapidly – in only 3-4 seconds – just like the AC vari­ants.

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.

Figure 2: Appli­ca­tions that require a rapid start-up of the fans used are e.g. air curtains for truck loading ramps. (Photo | iStock / Salima Senyavskaya)

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

Figure 3: At the heart of these fast starters, avail­able in sizes 160-250, is a Green­Tech EC motor.

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.

Figure 4: The EC centrifugal blower’s air perfor­mance range goes up to 3,000 m³/h.

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.

Figure 5: The bumps on the elec­tronics housing (circled in red) improve cooling.

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.

Figure 6: Inte­grated active power factor correc­tion (PFC) signif­i­cantly reduces the harmonic content in input current (left without; right with active PFC).

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.