The Short Summary A healthy AHF typically produces two types of noise: A low hum from the internal reactor (inductor) and cooling fans. This is normal. A high-frequency "switching" whine or buzz from the Insulated-Gate Bipolar Transistors (IGBTs). This is usually very faint. If the noise becomes loud, intrusive, or changes significantly, it is often a sign of a problem. Detailed Breakdow...
The Problem: Variable Speed Drives Generate Harmonics What is a Variable Speed Drive (VSD/VFD)?A Variable Speed Drive (VSD), also commonly called a Variable Frequency Drive (VFD) or Adjustable Speed Drive (ASD), is an electronic device that controls the speed and torque of an AC electric motor by varying the motor's input frequency and voltage. How Do They Cause Harmonics?The internal design of a ...