A novel split type on-load tap changer for converter transformers

In recent years， there have been several serious incidents involving explosions and fires in on-load tap changers （OLTCs） of converter transformers during the adjustment. To address this issue， a novel design solution for a split type OLTC is proposed， separating the switching part from the transformer body to effectively prevent the faults in the tap changer being intensified. The vacuum permanent magnet switch replaces each contact of the switch， and the operating mechanism is independently configured. Based on current sampling devices arranged in the internal circuit， monitoring and control of the switching process are achieved. Split type synchronous control logic and step control logic for the diverter switch are introduced to monitor the status and provide fault protection during the tap changer adjustment process. Experimental results from the prototype validate the feasibility and effectiveness of the proposed OLTC design for converter transformers.