Synchronous Power Transfer to Induction Motors Operating with Variable Frequency Drives Case 1: Residual Voltage and Fixed Time Transfer

The synchronous transfer is an exact procedure that allows one variable frequency drive (VFD) to operate multiple motors for process control. The paper analyses the function of synchronous transfer for utilization with variable frequency drives commonly used in pumping applications within the pipeline industry. There are three directions subject to study and testing: the equipment with synchronous transfer capabilities, different types of transfer available, and considerations regarding the safety of the operation. The experimental part of the project consists of assembling a system that assures the induction motors' transfer to and from a variable frequency drive as desired, a transient process that must not disturb the overall system significantly. Switching logic is handled by a Programmable Logic Controller (PLC). Waveforms captured of the system operating at specific times certify that the induction motor transfer occurs safely.