Full speed control without a VFD – EC fans from ebm-papst

Full speed control without a VFD! This is the beauty of EC fans with integrated speed control from ebm-papst.

Traditional speed control in buildings services applications is commonly achieved using variable speed drive (VSD) or variable frequency drive (VFD) systems. These systems are offered to the market by a broad range of manufacturers and are used because of market familiarity.

Direct costs

VFDs are often supplied by the electrical or controls contractor as part of their total package offering. They often require considerable time and cost to install. Typical installations often need separate fixtures on a site remote from the fan application and a range of specialty wiring and filter systems to ensure smooth noiseless control. These types of systems include double core shielded cabling as well as harmonic filters and power factor correction.

This is costly and time consuming and comes with a higher risk as there are more components to fail.

EC fans from ebm-papst have all these components included at the fan so that the cost of installation is taken care of and the risk of failure is minimised.

Hidden costs

There are some hidden costs with VFDs, e.g. they increase motor losses.

The International Electrotechnical Commission standard IEC 60034-31, Selection of energy-efficient motors including variable speed applications, states that the addition of a VFD increases motor losses by 2 to 5 per cent; in adverse circumstances it can increase motor losses up to 15 to 20 per cent.

The VFD also has its own losses with small drives being less efficient than large drives. The losses are also dependent on the drive switching frequency. The loss is less with low frequency switching, but this produces mechanical noise from the motor. The drive is therefore normally set at a high switching frequency but this increases its losses, for example a 1.1 kW drive is typically 95 per cent efficient at low and 92 per cent at high switching frequency.

EC motors from ebm-papst give considerable efficiency savings when compared to traditional AC motors with VFD as shown below:

If we compare a 1.1kW motor with VFD against an EC motor, it is shown that the standard IE2 1.1kW motor with VFD can be 73 % efficient, while the EC motor is typically 87% efficient.

This represents a 15% saving and therefore running costs savings even at full performance. These running cost savings are all in addition to the simpler installation -

EC is easy!

Watch the video on YouTube!