1EC FansEC Fans2Leonardo Evolution units offer the possibility to choose between two different types of Backward Curved Fans: Standard Asynchronous Fans on T*R units;Brushless Electronically Commutated Fans on T*V units.Brushless electronically commutated fans lead to the greatest benefits.OverviewOverview3EC (Electronically Commutated) fans, basing on “Brushless” technology, create substantial advantages in terms of:Lower Running costs compared to the traditional backward curved fans;More flexibility on the adjusting of fan speed basing on the real needs of the aeraulic circuit;High performance with low noise, thanks to a particular shape of this last generation impeller;Starting current lower than nominal current;Continuous fan speed regulation from the microprocessor;Integration, thanks to the possibility of interfacing with the AFPS and Active Floor System.OverviewOverview4In any motor, either the rotor or the stator, must have a rotating magnetic field in order to cause the motor to turn. This rotation can be accomplished by: General InformationGeneral InformationThree-phase AC power;Single-phase power with some sort of circuit element like a capacitor, inductor, or resistance to synthesize a second phase (that is timed differently from the first);An electro-mechanical commutator to switch power to different coil groups as the motor turns.5There are limitations with each of the previous methods:Three-phase AC power is not available everywhere and the frequency and voltage are constant, making the speed control difficult.Single phase power has all the characteristics of three-phase power. In addition, phase-shifting methods produce a very imperfect rotating field, tend to introduce considerable losses in the motor and produce a very weak starting torque.General InformationGeneral InformationAn electro-mechanical commutator solves several of the above problems. It can accomplish wide-range speed control, and it can provide high starting torque. The limitation is that the electro-mechanical commutator has friction and wear problems that reduce efficiency and require frequent maintenance. Also, a voltage controller has to be used to accomplish speed control.6Power SupplyGeneral InformationGeneral Information7Electronic commutation potentially eliminates all the previous problems. Power is pulsed on and off electronically with semi-conductor devices; the pulsed signals power three or more circuits or coil groups within the motor. By varying the timing and duration of pulses, the electronic controller can accomplish speed control and maintain high torque at start and over a broad speed range.General InformationGeneral InformationPower SupplyPermanent MagnetsCoils8The EC motor is equipped with periferal permanent magnets and internal electromagnets which are electronically commutated. The commutation is made by a power transistor, therefore there are non mechanical elements such as a collector of brushes which would noticeably reduce the life. In EC motors the magnetic field is generated by the same rotor thanks to the presence of permanent magnets. The commutation of the magnetic field is electronic and consequently free of wear and tear resulting from contact between static and rotating parts. The operating mode and the materials used lead to an increased efficiency which is shown in less absorption with the same performance.General InformationGeneral Information9BRUSH DC motor it requires carbon brushes to commutate (drive) the motor limited operating hours, few 1000hBRUSHLESS DC motor (EC motor) no carbon brushes required extremely long service life, commonly over 80.000hStartup Current = 3.5 x Nominal CurrentStartup Current Nominal CurrentAdvantages of the EC motorAdvantages of the EC motor10With the EC motor, the magnetic field is generated in the rotor itself by permanent magnets. Commutation is electronically and therefore without wear-and-tear. Depending on their layout and the application, EC motors can be operated from: the DC power supply via an external / integrated commutation unit directly from an AC mains supply.Basic Principles of the EC motorBasic Principles of the EC motor11EC motors are controlled via PWM or linear (0-10 Vdc) input signal. There is an open loop speed control so that the speed changes depending on the load. Closed loop speed control is possible with integrated electronics. There are inputs for potentiometers, 0-10 Vdc or PWM signals.PWM (pulse width modulation)A PWM signal is a square wave signal with a variable pulse-pause ratio.Linear closed loop /open loop speed controlAt 0 Vdc, the motor is de-energised and does not rotate. From 1 Vdc onwards, the motor starts to run. Maximum speed is reached at 10 Vdc.CharacteristicsCharacteristics12Input voltage range:380-480VAC Frequency:50/60 Hz Input power:max. 3kW Protection:IP54 Control input0-10 Vdc100 kAmbient temperature: -20 bis +55C -20 b