Abstract: During the vacuum pumping process of a 500 kV tank circuit breaker, it is not possible to accurately read the inlet data of the vacuum unit. Closing the vacuum unit to read data can easily cause the vacuum pump oil to pour into the equipment. In response to the above issues, it is proposed to add a three-way, ball valve, and electronic display meter on the circuit breaker body side. Its operation is simple, data reading is accurate, and operational risks are reduced.