Standard electric motors turn electricity into rotational power.
They work by energising electromagnets that generate magnetic force. This is turned into rotational power which is used to rotate the fan blades. All fans have the electromagnets fixed to the motor body and the rotor spins around the magnets forcing the fans to spin and direct the air through the fan body.
The rotor has permanent magnets around its circumference, and magnets have both a positive and a negative pole. The magnets are arranged so the poles of the magnets alternate between positive and negative. As the electromagnets are energised they are either positive or negative and repel or attract the permanent magnets in the rotor. This makes the fan spin causing air movement, the faster the magnets are energised the faster the fan spins.
What is an AC Fan Motor?
AC (Alternating Current) motors use the alternating current from the main supply directly to energise and change the pole of the electromagnets. In the UK the electricity alternates between positive and negative at 50 Hz or 50 times per second. This means that the electromagnets in the motor change from positive to negative 50 times per second. AC motors under a normal load at full speed are efficient, economical to make, and offer years of reliability.
Speed controlling AC motors
Controlling the speed of an AC motor is a challenge – one method that can be used is a Triac controller. This is essentially an electronic switch that switches on the electro-magnets for only a proportion of each cycle. As the same amount of power is input, the unused power is lost, creating buzzing and humming at low speeds. The second method is a stepped hybrid controller, which reduces the voltage with a transformer, reducing the magnetic strength and in turn reducing the speed of the motor. Transformers only offer a limited number of steps (usually 5 steps). The benefit is that as the frequency remains constant there is no humming or buzzing.
Benefits of AC motors
- Highly economical
- Very efficient at 100% speed
- Quiet in operation (at high speeds)
- Cost effective and reliable
What is an EC Fan Motor?
NEW EC technology (electronically commutated) motors convert alternating current (AC) into direct current (DC). The current is then used to energise the electromagnets. The DC current also converts the electromagnets from positive to negative. The intelligent built-in electronics in an EC motor constantly monitor the exact location of the external rotor and only energise the electromagnets when they are needed, and with the correct amount of power to maintain the speed. EC motors use less than half the power at half the speed.
Controlling EC motors
EC motors are controlled by supplying a low voltage signal from a controller (10 volt = 100% speed, 0 volt = off ). EC motors can run at very low speeds and will remain silent because the power is not being cut during the AC cycle to control the motor, as with AC fans. EC motors can perfectly maintain environments by altering the speed in very small increments, stopping any sudden movements in room temperature or humidity. EC motors are built for years of hassle free service.
Benefits of EC Motors
- Easy to control
- Highly efficient at different speeds
- Built-in controller
- Silent at all speeds
- Effective digital technology