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Fan speed controller for single phase motors - 230 VAC supply

VFSC9 fan speed controllers regulate motor speed by reducing motor voltage. These controllers guarantee quiet motor operation in all circumstances by maintaining a sinusoidal shape of the motor voltage. The speed controller itself works completely silently anyway because it only contains electronic components. Because VFSC9 controllers only modify the motor voltage and not the frequency, they are easier to operate than frequency converters.

VFSC9 is available with analogue input for speed control via an external 0-10 Volt control signal. The other variant also has the analogue input and a built-in potentiometer on the front panel. In this variant you can choose either to control via an external 0-10 Volt control signal or for manual operation via the built-in potentiometer.

VFSC9 versus frequency converters

The big difference with a frequency controller is the lack of a DC bus. A frequency controller will convert the sinusoidal supply voltage into DC voltage and then use the IGBTs to convert it into a sinusoidal signal again. This makes it possible to change not only the amplitude of the motor voltage but also the frequency. The disadvantage of the DC bus is that additional configuration is necessary. VFSC9 controllers don't require configuration. Where a VFSC9 can immediately control the motor, a frequency converter must first be configured. The absence of the DC bus not only makes VFSC9 easier to use, it also ensures that the device is cheaper compared to a frequency converter for the same motor power. 

VFSC9 versus TRIAC controllers

The high switching frequency of the IGBTs makes the big difference with TRIAC technology. An IGBT is an electronic component that can switch much higher currents at much higher speeds than a TRIAC. Thanks to this high switching frequency, the motor voltage can be reduced in a very even manner. Instead of cutting away one large piece of sinusoidal voltage, several small pieces are removed. The final signal will still be sinusoidal. This is the big difference with TRIAC technology, where one large part of the sinus is removed, so that the motor signal is no longer sinusoidal and the motor becomes noisier at lower speeds. VFSC9  controllers guarantee quiet motor operation in all circumstances. 

The VFSC9 speed controller can be called an 'AC chopper'. It uses IGBT technology to reduce the motor voltage via phase angle control. VFSC9 controllers only change the amplitude of the voltage, not the frequency of the supply voltage. This is in contrast to a frequency controller. The IGBTs of this speed controller chop away parts of the supply voltage at a very high frequency. This allows the motor voltage to be reduced in a very even manner. This makes it possible to continuously variable control the fan speed. The IP54 housing protects the electronics against the ingress of moisture and dirt.
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