An ON-LOAD tap changer allows changing taps without interrupting power to the load. Currently available tap changers for this application are mechanical types with contacts that arc and pit every time a change is made. A Solid State tap changer would overcome these short comings; in addition, it would allow remote tap changing, integrating tap changing in process control systems, and would readily change the taps to suit systems needs thus yielding more optimum power conditions. A Solid State tap changer would select the tap connection by turning on a thyristor gate. Fiber optics would be used to isolate control from high voltage. The objective of this research will be to develop the necessary control circuits and protection and annunciation circuits, and to protect the thyristors against high system voltage. Detailed system specification would be developed for a 35 KV, 100 amp solid state ON-LOAD tap changer. A low voltage evaluation bread board model would be assembled and tested.The potential application as described by the company:A Solid State, Fiber Optics isolated ON-LOAD tap changer for industrial and utility use would be developed to allow integration of tap changing into automated control systems. Application should be in AC and DC drives for paper, textile, steels, and other metal rolling mills; transit traction applications, distribution substations and network applications. The advantages are the following: (1) Solid State operation (more reliable, longer operating life), (2) Remote control of tap position, (3) Automatic selection of tap position by process control computer, (4) Instantaneous peak load handling capability by boosting system voltage for short times, and (5) Integration of tap changing into utility distribution grid control.
