Like every electric motor our external rotor motor consists of a stator wound with copper wire and a rotor. The difference is that the rotor rotates externally around the stator. The complete fan unit, i.e. the small external rotor motor equipped with an impeller requires minimum space. The unique integration of both rotating part - the motor and the impeller - permits precision balancing. Both the motor and the impeller are directly in the air stream and are thus very efficiently cooled resulting in minimum thermal and mechanical stress on the bearings which extends lift expectancy.

In accordance with EN 60335-1 our motors have insulation class "B" or "F" and protection class IP44 or IP 54.

Our fans are supplied with built-in thermal contact (TK). At the critical high temperature point ("B"=130 °C or "F"=155°C) the thermal contact will open and break the power supply to the fan.

The conventional over current relay is exchanged into a thermal contact relay which means the motor has a far better protection against burn-out. This is especially important if the fan is speed controlled, as it is impossible to state an exact over current.

Built-in thermal contact
Fans with built-in thermal contact with automatic reset. At the critical high temperature point the thermal contact will open and break the power supply to the fan.

External thermal contact
These fans are supplied with two leads from the built in thermal contact (TK). At the critical high temperature point the thermal contact will open and break the power supply to the motor protection. The thermal contact leads (TK) must always be connected to a relay to ensure safe running (STET 10, if current is less than 0.45 A, must the AWE-SK be used) for single phase or STDT 16 for three phase). After a high temperature cut-out the relay must be reset manually after examination of the fault. To control the relay just loosen one of the TK leads and the motor will stop in a few seconds. Our single phase transformer RTRE and our three phase transformer RTRD have a built-in thermal relay.

Ball bearings are completely maintenance-free and can be used in any mounting position, at maximum indicated temperature. The bearing lubricant is suitable for a minimum ambient temperature of minus 15°C (admissible for a short time without reaching dew point at -30°C). For applications at maximum indicated ambient temperature life expectancy L10 is 40.000 hours minimum.

The forwards curved impellers are of galvanized sheet steel. The backward curved impellers are made with either plastic impellers on a disk of galvanized sheet steel or entirely of galvanized sheet steel. The impeller are press-fitted directly onto the rotor of the external rotor motor.

Motor (motor and impeller) is dynamically balanced in two planes to DIN ISO 1940.

Fans with single inlet the direction of rotation is indicated when "viewed from the rotor side". For motors with double inlet the direction of rotation is determined when "viewed from opposite cable exit".

Maximum power consumption of forward curved impellers is reached at free blowing. As the back pressure increases, the power consumption decreases. Maximum power consumption of backward curved impellers is reached in the low back pressure area (first third) of the characteristic.

Motors comply with EN 60335-1.

Almost all fans have casings made of hot-rolled galvanized sheet steel according to EN 10 142. 10 147. The sheet metal have a layer of minimum 20 mm zink which gives a very good protection against corrosion. The galvanized sheet metal parts are either spot-welded, screwed or mounted together with rivnuts.

KVKE, RS, RSI, CKS, TOD and TOE have the motor on a swing-out door which make the cleaning and service of the fans very easy.

Rectangular fans are available in size from 300x150 mm to 1000x500 mm, circular fans are available in sizes from 100 mm to 500 mm and square fans are available in sizes from 450x450 mm to 650x650 mm. For dimensions see drawing on page for suitable fan.

Our series *K, *KV, KD, RSI, TOD, TOE, TFER, RVF have casings with powder coating. It gives the fans a very good protection against corrosion and a very nice finish of the product. Powder coating has a hard surface with preserved elasticity. These qualities of powder coating makes the surface very resistance against damage. At powder coating solvent are not used which gives minimum environmental influence. On our fans we are using three colours black (roof fans) or blue (duct fans) or white (RVF). The thickness of the powder coating is minimum 40 mm.
* K and KV are available with or without powder coating.

Our series KVK, KVKE, RSI, TFEQ, TFDQ, are insulated with 50 mm mineral wool. The sound absorbing characteristic are very high for these fans which give them a very low noice level.

The insulation is resistent against fire.

The insulation are made of semi-rigged and rigid impregnated mineral wool slab with facing of natural non-wowen glass fibre on one side. Density is 130 kg/m³ . The insulation are water repellent non-hygroscopic and non-capillary. Moisture has no effect on the stability. Water vapour diffusion resistance factor m=1.3. Fire classification according to ISO 1182 and NT FIRE 004. Material non-combustible. Service temperature is 250 °C and softening temperature >1000 °C.

For single phase fans capacitor is rated 400 V. The required capacitance in µF is shown in table for each single phase fan.
Capacitor is delivered wired with each fan.

All fans can be installed in any angle. We recommend horizontal mounting for the roof fans. We also recommend that the fans are mounted with fastclamps (circular) or flexible connections (rectangular) to eliminate transferring of vibrations to the duct system.

AAll duct fans are speed controllable by lowering the voltage from 100% to 0%. This is achieved by using a stepless thyristor or a 5-step transformer.
The five curves in the fan diagram represent the 5 different voltages of our transformers:

The fans should be connected to the electrical supply as shown on pages wiring diagram.

Please note!
Guarantee is void if a thermal contact relay is not installed properly.