Intel­li­gent EC tangen­tial blowers for venti­lation tech­nology

New tangen­tial blower with low-voltage drive for building air-condi­tioning

Added up over the years, oper­ating costs in build­ings are a substan­tial cost factor and almost always higher than the initial invest­ment. Many of the compo­nents used are in oper­a­tion round the clock for years. As a result, even small improve­ments in the effi­ciency of the heating and cooling systems pay off quickly. If the purchase price of the improve­ment is cost-neutral to existing solu­tions, the savings start imme­di­ately. A new drive tech­nology for tangen­tial blowers in floor ducts combines two advan­tages: lower energy consump­tion with almost unchanged invest­ment costs and expanded control options.

Targeted air conduc­tion is impor­tant for an optimal room climate. In order to create the neces­sary prereq­ui­sites for this, the air is moved by smooth-running tangen­tial blowers, espe­cially in instal­la­tions with floor ducts (under­floor heating and cooling systems). Kamp­mann, a company based in Lingen, Germany that specialises in building air-condi­tioning, has worked with this tried-and-tested system for years. However, to attain even better results in terms of energy effi­ciency and smooth running, the devel­opers from Kamp­mann and ebm papst are using a new drive in state-of-the-art EC tech­nology. This combines energy-saving oper­a­tion with a long service life, easy instal­la­tion and simple control.

Keeping total cost of owner­ship in view

New tangen­tial fan with energy-saving EC drive system

The total costs over the service life of a venti­lation system can be reduced signif­i­cantly by the correct selec­tion of a few compo­nents, such as fans. There­fore, the following primary criteria exist for the fans built into floor ducts: they must be cost-effec­tive, main­te­nance-free, quiet in oper­a­tion, save as much energy as possible and be easy to install. A tangen­tial blower design fulfils exactly these require­ments. The many blades of the fan roller enlarge the surface area that propels the air, enabling the rota­tion speed to be reduced and so allowing very quiet oper­a­tion. The twin fan version circu­lates even greater volumes of air.In the past, these were often driven by shaded-pole motors as these are inex­pen­sive at the time of purchase. However, a major draw­back of this solu­tion is its rela­tively low effi­ciency.

To keep noise levels low, it only works at 1400 rpm, but at this speed it is espe­cially inef­fec­tive as a two-pole drive on a 50 Hz power line. That means firstly, increased power costs for the many fans needed in the building, and secondly, in the summer the cooling system also has to conduct the residual heat of the motor away, which requires even more energy. In order to be effi­cient and keep up with state-of-the-art tech­nology, the air-condi­tioning experts at Kamp­mann are now employing the inno­v­a­tive drive concept from fan experts ebm-papst. The intel­li­gent incor­po­ra­tion of EC tech­nology in the new KaCon­trol building automa­tion system even allows the cost-neutral imple­men­ta­tion in under­floor appli­ca­tions.

Outstand­ingly versa­tile EC drives

Katherm floor convector for heating or cooling

The elec­tron­i­cally commu­tated direct current motor concept is ideal for meeting the require­ment for high effi­ciency with a long service life and robust design. In this design, elec­tronics inte­grated into the drive carry out the commu­ta­tion instead of carbon brushes. It always governs the motor current opti­mally depending on the required power and speed. For this reason, effi­ciency remains uniformly high over a very wide speed and load range. This saves energy and minimises waste heat. The inte­grated elec­tronics enable conve­nient control of the drive and reduce the need for external control tech­nology dras­ti­cally. The low-voltage drives require a mere 24 V DC as supply voltage, providing optimal reli­a­bility, espe­cially in floor ducts.

Intel­li­gent motor manage­ment ensures a constant speed, regard­less of load, depending on control voltage. More­over, it is possible to program special speed control “ramps” from the factory in depen­dence on the control voltage in the fan. This allows air circu­la­tion to be adjusted to the require­ments of the instal­la­tion directly in the fan, which simpli­fies the external control system.With internal rotor motors, the larger sepa­ra­tion between the bear­ings improves the stability and smooth running of the rotating parts. Not even the “rough handling” encoun­tered on the construc­tion site has any major effect on the func­tion or reli­a­bility of the fans.

Customised air flow

Katherm floor convector with inte­grated EC tangen­tial blower for heating oper­a­tion

At present, there are two fan versions avail­able. The QLK45/0030-2212 with an air outlet of 300 mm and the twin fan version QLK45/3030-2212 with 2x 300 mm air outlet. The total instal­la­tion size is 395 x 79 x 70 mm (single fan) or 755 x 79 x 56 mm (twin fan). Both versions work with 24 (18…26.8) V DC and a control voltage of 0…10 V. An inte­grated Hall sensor (2 pulses per revo­lu­tion) provides signals for the internal elec­tronics, but these signals can also be picked up at the connector socket for external use. In the twin roller version, the fan displaces up to 72 l/s running at free air, with a maximum delivery pres­sure of 37 Pa. The power input in the char­ac­ter­istic diagram is just 6 to 10 W.

State-of-the-art drive engi­neering saves energy and instal­la­tion time and thus real money, even in common current fan concepts for building air-condi­tioning. Inherent energy consump­tion is reduced by effi­cient motors, inte­grated elec­tronics make instal­la­tion easier and savings in control compo­nents are attained. Intel­li­gent inte­gra­tion into the building automa­tion system is the finishing touch that provides a clearly measur­able increase in effi­ciency of the system compared to the conven­tional design, for the same invest­ment. The instal­la­tion engi­neer saves labour hours; the owner/operator saves energy and thus costs, with a greater degree of comfort.

The design of the EC drive

Air perfor­mance curves of the EC tangen­tial blowers

In the EC motor, the drive winding is housed in the motor jacket. The direct contact to the sheet jacket enables good heat dissi­pa­tion. The low heat load, in turn, extends the service life of the motor bear­ings. The magnetic rotor consists of the gearbox output shaft and the rotor itself in the form of a perma­nent magnet with what is called the commu­ta­tion track. Depending on the control solu­tion used, speed (Hall) sensors provide the control elec­tronics installed on the bearing shield with the neces­sary infor­ma­tion about the posi­tion of the anchor. During this process, a simple control voltage between 0 and 10 V provides the elec­tronics with the desired setpoint rpm. From the supply voltage, the control elec­tronics gener­ates a magnetic rotary field in the stator coils that depends on the speed and load. This always ensures the best possible effi­ciency at every speed.