Compact, radial fans have free-running impellers and variable speeds, combining electronically commutated external rotor motors with new integrated power electronics. The brushless DC motors are controlled by maintenance-free electronic circuitry. GKHR model fans are motorized impellers, mounted and balanced, that can be provided with or without an inlet cone. GKHM model fans are complete fan modules.
The external rotor design and high power density are said to make them ideal in ventilation and air-conditioning applications. Reduced mechanical content is said to help them run cooler and quieter, requiring little or no maintenance, and they can be speed-controlled using an external potentiometer or 0-10 V PWM signal.
Unlike conventional DC motors, the new EC motors are said to deliver highly efficient, low-noise performance without using collectors and carbon brushes that wear out and shorten motor life. In the new models, the power supply and control leads connect directly at the motor, said to simplify installation. In pressure control applications, the EC motors can be direct-connected to a pressure sensor. In master-slave designs, the pressure controlled output of the master fan controls slave unit speeds. Rosenberg USA, www.rosenbergusa.com