What are the requirements for the Longitudinal differential

The Longitudinal differential maintenance of the transformer shall be in accordance with the following requirements: 1) shall be able to avoid the inrush current and external short circuit generated by the unbalanced current. 2) the differential maintenance scale shall include the transformer bushing and its lead line. If it can not include the lead line, should adopt a rapid removal of the auxiliary method. However, in 63 kv or 110 KV voltage level of the terminal substation and branch substation and electrical main wiring with bypass bus, in the withdrawal of transformer circuit breaker by bypass circuit breaker to replace, Longitudinal differential maintenance can use transformer bushing current transformer, lead wire can no longer adopt the auxiliary method of rapid removal of defects.