Technical information
EC fans combine the advantages of
AC and DC fans
State-of-the-art technology of AC fans
For more than 60 years, AC fans have been employed not only for cooling electronic devices and components but also for ventilation purposes. AC fans are extremely robust and although the simple electric motor has no mechanical commutation they do have a relatively high power input. While several improvements since then have positively enhanced the efficiency, they have not fundamentally changed the fan. Disturbing is the fact that AC fans require a defined operating voltage where the frequency is linked to the speed and consequently to the volume flow rate. Neither the function monitoring nor the speed control can be included. Negative aspects are the considerable weight and the fact that the manufacturing of these simple devices involves the use of large quantities of expensive raw materials, e.g. aluminium and copper.
Low-voltage DC fans
It was only thanks to the development of semiconductor technology, that it became possible to develop DC motors without mechanically operating collectors and furthermore to integrate the electronics required for commutation into the DC fan. DC fans are highly durable and are operated with low voltages of 5, 12, 24, seldom 48 VDC and compared to AC fans with the same volume flow rate, they only have a fraction of the power input. They contain very little copper. The housings and rotors are made from glass fibre-reinforced plastic and therefore weigh less.
EC fans
Fans operated with alternating current are required when direct current is not available, e.g. in non-electronic systems and devices for cooling and ventilation purposes. EC fans combine the advantages of both AC and DC fans. EC stands for electronically commutated DC fans. For operating from the mains, EC fans are equipped with an integrated AC/DC converter that rectifies the higher AC voltage to a safe direct voltage. Only by employing the latest electronic components was it possible to integrate the motor commutation and the complete AC/DC converter into the hub of the fan without increasing the outer dimensions.
AC, DC and EC fans in comparison
The illustration on the left shows the conventional AC fan with the dimensions 120x120x38mm. It has an asynchronous motor with an external stator winding. The illustrated rotor has an internal laminated core. This construction is referred to as a squirrel cage rotor.
The EC fan in this illustration cannot be distinguished from a DC fan. It has an internal four-pole stator winding. The commutation electronics are mounted underneath the motor, as in the DC fan. The AC/DC converter is located on the back of the PCB. To the right of it in the rotor is a four-pole plastic magnetic ring.
EC fans for higher demands
This illustration shows an EC fan with Protection Class IP68, in other words with fully encapsulated electronics. It should be noted that the complete protection against the ingress of water only applies to fans with a sealed connecting cable.
Fans that are connected to the mains via a plug-in connector have limited protection inside near the rotor. The plug-in connector on the outside of the fan housing is not waterproof and therefore does not have adequate protection.
The illustrated fans in the examples have a power input of 20W (AC/50Hz) and 5W (EC) with a similar volume flow rate of approx. 180m3/h. Larger EC fans are also equipped with highly permeable NdFe magnets and are even more effective.
EC fans in the standard sizes can be interchanged mechanically and electrically with AC fans, however they do boast the major advantages of DC fans:
- Universally usable in all power supplies including unstable (mobile) ones that are available worldwide, also in DC networks
- Speed is not dependent on the network frequency
- Can be equipped with function monitoring and / or PWM speed control
- Up to 75% less current consumption
- Up to 40% lighter in weight
- Virtually no self-heating
- Longer service life
- Global certification: UL, CE, ROHS
Operating costs are significantly reduced
EC fans are more expensive than AC fans due to the additional electronics that are required for the AC/DC converter. Thanks to the simplified model approach due to the universal input voltage range and above all due to the much lower power consumption costs, the higher acquisition costs are compensated for not only after a short operating period but even the operating costs are significantly reduced over the entire plant runtime.
How the EU Commission Regulation 2024/1834
affects developers
The new and stricter EU Commission Regulation takes effect on 24 July 2026. This regulation stipulates a higher efficiency for fans with an electric input power of 125W and above. It is to be expected that it is only a matter of time until this performance limit drops further. This means that the very large numbers of small and medium-sized fans installed in e.g. cooling units in food retailing and for ventilation purposes will have to be operated in a more environmentally-friendly manner, above all in systems that operate continuously or are designed for long-term operation. With this in mind, EC fans are regarded as a future-proof solution as they are generally more efficient, offer better controllability and further advantages when operating continuously.