Rosenberg / Centrifugal Blowers

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Casing
The casings of the high efficiency centrifugal fans are made of galvanized sheet metal. The side parts are produced with nut sets to fix the mounting brackets, which can be fixed in steps of 90°. Epoxy coating on request.

Impeller
The impellers with 38-42 forward curved blades are made of galvanized sheet metal. They are mounted directly to the external rotor motor. The impellers are statically and dynamically balanced together with the external rotor motor according to quality level G2.5 DIN ISO 1940.

Direction of rotation
Direction of rotation for fan types ERA is clockwise viewed from the inlet side, but for fan types DRA it is anti- clockwise viewed from the cable outlet. Caution: Low air volume at wrong direction of spin!

Motors
Rosenberg external rotor motors are manufactured in protection class IP54. The winding insulation corresponds to insulation Class F (UL - approved). Bearings are deep groove ball type in sealed housing. Special grease lubrication provides maintenance-free operation, low-noise and extended life.

Motor protection
All motors are equipped with thermal contacts, wired in series. Thermal contacts are temperature dependent control elements, sensing the winding temperature of the motor These contacts protect the motor windings from overload, failure of a mains phase, standstill of the motor and of high temperature rise to the medium ventilated.

AVAILABLE VOLTAGES
For single phase operation, motors are available for 115V, 208V, 230V and 277V. For three phase operation, motors are available for 208V, 230V, 460V, 575V. Other special voltages are available on request.

SPEED CONTROL
Speed control is obtained by “Voltage Control” and “Frequency Control” as described below.
Voltage Control.
The speed control is provided by reduction of the terminal voltage. If the voltage will be reduced the speed of the motor decreases and the air volume flow sinks in proportion with the speed.
Frequency Control.
All voltage controllable fans for three-phase power supplies can also be speed controlled by frequency converter from 60Hz downwards. The speed control is realized by reduction of the power supply frequency. At higher frequencies than 60Hz the motor will be thermally overloaded. With operation of the motors on a frequency controller the maximum speed of voltage increase of 500V/μs must not be exceeded. According to the frequency converter type and the length of the cable between motor and frequency converter additional components must be planned. Please refer to the operation manual of the frequency converter.

Advantages of Rosenberg high efficient centrifugal fans:
• Compact and space saving design with external rotor motor drive and high performance forward curved impeller
• Low for maintenance direct drive fans (no belt wear or belt replacement necessary)
• Various control possibilities
• Customers requirements can be met without problems
• Easy installation in any position
• Extremely low starting currents
• Motor protection through thermal contacts in motor winding


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