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What Are Force Ventilation Fans ?

Force Ventilation Fans (sometimes known as FV fans, force vent fans or force vent units) are a cooling device that fit onto the non-drive end of an AC electric motor.  Force vent fans provide constant cooling across the body of the motor irrespective of the motor shaft speed.

Why Do I Need A Force Ventilation Fan?

Most standard AC induction motors have a cooling fan mounted at the non drive end of the motor shaft, covered by a fan cowl. The fan blade rotates at the same speed as the shaft.  This fan provides optimum cooling performance when the motor is run at it's standard design frequency of 50 or 60 Hz.

Many electric motors are now controlled by variable speed drives or inverters.  These devices can change the speed of the motor.  By reducing the speed of the motor, then the speed of the cooling fan also reduces, which in turn reduces the cooling effect of the standard fan.  The use of a force ventilation fan guarantees adequate motor cooling irrespective of the motor shaft speed.

What Happens If I Don't Use A Force Vent Fan?

If you don't use a force ventilation fan on a motor that is running at less than 25 Hz, you may experience:

  • Motor over-heating
  • Reduction of output power
  • Motor winding stress
  • Thermistor over-temperature faults
  • Reduced motor life

Axis Controls supply Force Ventilation Fans for most major brands of motors.  However, if we don't stock the exact model to suit your requirements, please contact us as we can usually adapt a similar unit to your specification.

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