Minimizing refinery upset during power interruptions using PLC control

When a refinery electrical distribution system experiences severe voltage dips or short duration power interruptions, online starters deenergize and motors stop, resulting in plant upset. To minimize the impact of momentary power disturbance, it is desirable that motors used for critical services can be restarted automatically and sequentially. Power disturbance criteria for selecting critical motors, mainframe computer studies to determine the system´s optimum reacceleration load, and development and design of programmable logic controller (PLC) programs are presented. The reporting functions to verify reacceleration system performance are described, and field measurements are presented