Changes to the 2020 NEC include the addition of several paragraphs in section 430.122. These changes will help the user to determine the correct ampacity for conductors used with power conversion equipment. The Adjustable Speed Drive is one type of power conversion equipment that provides a means of adjusting the speed of an electric motor, 100. A Variable Frequency Drive, VFD, is an adjustable speed drive that controls the speed, the RPM, of a motor by controlling the frequency and voltage supplied to a motor. The changes made in 430.122 Conductors – Minimum Size and Ampacity apply to Adjustable Speed Drive Systems.
Branch-Circuit Short-Circuit and Ground-Fault Overcurrent Protection is the final article of a four part series. The series is titled “Motor Calculations” and covers the Code and calculations for single general motor applications.
We considered how to properly size a typical motor branch circuit using the motor load as determined with the appropriate table and then multiplying that number by 1.25, reference 430.22.
By: David Herres – Variable Frequency Drives (VFD’s), also referred to as Adjustable Speed Drives, are prominent in today’s workplace. They are used in elevator, water pump, high-volume air compressor applications and material-handling systems wherever speed and torque characteristics of AC motors are regulated. In Thomas Edison’s time, the DC […]
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