Development and tests of ZW-126/D2000-40 vacuum circuit breakers with controlled switching technology

A ZW-126/D2000-40 type single-break vacuum circuit breaker (VCB) with controlled switching technology is designed and produced in this paper. The results of type tests based on IEC and GB standards are presented. A 126 kV single-break vacuum interrupter (VI) with 3/4 coil axial magnetic field (AMF) contacts is used in the VCB, which can interrupt short currents of 40 kA. The external insulation of the VI is provided by SF
6
at 0.1 MPa. In order to match the 126 kV single-break VI and controlled switching device, a long-stroke electro-magnetic force actuator (EMFA) with 16 kN closing holding force and 3.5 m/s average opening speed is designed. Moreover, a position tracking controlled switching device based on closed-loop control using the technology of a fuzzy control algorithm and pulse width modulation is applied to the controlled switching device. This device is applied to control the coil current of EMFA and the electromagnetic force, so as to control the EMFA to follow the ideal position curve. The type tests of 126 kV VCB are all passed according to the IEC62271-100 and GB1984-2014, including dielectric tests, basic short-circuit tests, short-line fault tests, out-of-phase tests, etc. The strong capacitive current breaking capacity and mechanical strength of the VCB are proved by the capacitive current switching test of class C2, electrical endurance test of class E2 and mechanical endurance test of class M2. The electromagnetic compatibility (EMC) tests are passed according to the IEC61000-4. The controlled switching test of capacitive current was successful according to IEC62271-302 and GB/T30846-2014, and the controlled switching accuracy is less than ± 0.5 ms. The test results show that the VCB has excellent performance, which has broad application prospects in special occasions at a 126 kV voltage level, such as a switching capacitor and no-load transformer, etc.