How does a Variable Frequency Drive work?
A variable speed drive works by converting a motor’s fixed incoming electrical supply into a variable frequency output. This way the inverter drive can control the motor speed.
What is the difference between a Soft Starter and a Variable Frequency Drive?
Both of these devices can only be used on AC motors. The difference between a soft starter and a variable frequency drive is that the soft starter is designed to start or stop a motor under reduced starting torque and current by varying the motors supply voltage from minimal to full rated value. When the motor reaches its designed operating speed, the soft starter has done its job and the motor must be switched to the mains power supply. Meanwhile, variable frequency drives control a motor’s operating speed by changing both its applied voltage and its frequency; the VFD can be left in circuit to operate the motor continuously and efficiently.
How does a variable frequency drive save energy?
Variable Frequency Drives can save energy by altering the speed at which motors operate. This can result in less energy consumption; it can also help to preserve the life of your motor as it won’t have to work as hard when lower speed rates are set. When connected to a centrifugal fan or pump motor for example, reducing the frequency (motor speed) by 20% will normally save around 50% of its consumed energy when compared to operating the motor at 100% speed and reducing the air or liquid flow from the fan or pump by partly closing a damper or valve.