In some single-phase induction motors the current drawn at no load is relatively high because the stator windings still supply all the magnetic field energy. This means that even during low load the motor can draw the majority of its full load operating current. This excess energy is converted into heat and vibration, in addition to the energy being wasted the heat and vibration shortens the life of the motor.
In the single-phase induction motor the current lags the voltage due to the inductive reactance in the windings. The cosine of the amount of lag in degrees is the motor power factor. Power factors are 1 for resistive loads (heaters etc) and typically vary from 0.65 for a fully loaded motor to as low as 0.1 for an idling motor
The actual power being consumed by the motor is Voltage x Current x Power Factor. A lightly loaded motor has a low power factor, as the motor reaches its rated load the power factor moves closer to its designed maximum. iMEC calculates the motor loading by measuring the time delay between voltage and current zero crossing points, in effect the motors power factor.
When the load on the motor is low iMEC lowers power consumption by lowering the voltage to the motor by switching an SCR at the correct time in the voltage cycle, therby saving energy. iMEC continually adjusts the power to the motor every mains cycle to ensure the motor always has enough power to suit the driven load.
The iMEC range of Intelligent Motor Controllers will:-
- Save up to 40% in energy costs
- Reduce peak demand charges
- Improve power factor
- Reduce heat, noise and vibration
- Reduce maintenance costs
- Extend equipment life
Learn more about iMec here