If the fan is required to operate in conjunction with controllers such as single-phase and three-phase autotransformers, single-phase electronic phase-controlled controllers or frequency converters, it must first be ascertained whether the control can be applied to each type of fan. Information on the possibility of speed control can be found in catalogues, technical specifications or operating instructions. If you are unsure, always contact our technical specialists. However, the manufacturer's recommendations must always be followed.
D/Y switching control
Some fans we supply are equipped with 400 V three-phase motors that can be switched D/Y. This is a voltage control that allows, for example, to permanently reduce the speed or reduce the starting torque and starting current when the fan is connected to the mains.
Winding switching control
Some of the fans we supply are equipped with 400 V three-phase motors that can be used to switch windings. This is a speed control by changing the number of poles, which makes it possible, for example, to permanently reduce the speed or reduce the starting torque and starting current when the fan is connected to the mains.
Autotransformers
They are generally suitable for voltage control of the speed of asynchronous motors with a short-circuit resistive armature. They cannot be used in most cases for so-called IEC standardized motors. However, the manufacturer's recommendations for regulation must always be followed. The advantage of these regulators is that they do not cause additional heat losses through higher harmonics which reduce the usable motor power. The limitations of the operating characteristics with voltage regulation are indicated in the documents, if in doubt consult our engineers.
Phase Controlled Regulators
They are generally suitable for voltage control of the speed of asynchronous motors with shorted armature resistance. They cannot be used in most cases for so-called IEC standardized motors. However, the manufacturer's recommendations for regulation must always be followed. The disadvantage of these regulators is that they cause additional heat losses through higher harmonics which reduce the usable motor power. The limitations of the operating characteristics with voltage control are indicated in the documentation for first harmonic controllers, for phase controlled controllers a significantly larger area of unauthorised operation must be considered. The controllers produce a wide range of higher harmonic frequencies which, if operated without sufficient filtering, may cause additional noise (whistling, humming, etc.). If in doubt, consult our engineers.
Frequency converters
The requirement for control by electronic frequency converters or inverters must be specified in the order. The motors are highly stressed by the inverters and therefore require a special insulation design. When powered by inverters and inverters, the magnetic circuits, windings and insulation are stressed by high amplitudes of higher harmonic frequencies, which are the product of pulse width modulation of the output voltage.
Fan inrush currents
The inrush currents of asynchronous motors used in fans reach several times the rated current (about 2 to 10 times) depending on the armature design (internal or external, resistive, etc.), power and overall design. When operating with a frequency inverter (for normal fans) or with an inverter (for fire fans), the inrush current usually has no influence on the inverter sizing. Frequency converters and inverters usually contain "soft" start-up circuits. This means that the motor starts up gradually with reduced voltage and frequency so that the current does not exceed the inverter current. The rated motor parameters are usually critical for sizing.
Caution
Speed controllers and frequency converters can only be used with motors approved by the manufacturer. Speed controllers and frequency converters cannot be used with high temperature fans with dependent cooling (bearings, motor and other fan components are not cooled when the speed drops). Always consult the inverter or inverter supplier and the fan manufacturer for details on the suitability and safety of the inverter. Operation of phase-controlled controllers and frequency converters, especially without filters on the inlet or outlet, may interfere with or damage other electrical or electronic equipment.