A compound circuit is described for development and acceptance testing of circuit-breaker modules and circuit breakers up to 50,000 equivalent 3-phase module mva (megavoltamperes). The paper discusses high-current-source voltage requirements, synchronization of high-voltage-source application with final current zero, and high-voltage-source impedance requirements. Flexibility of the recovery voltage wave shape is demonstrated and its response to post-arc conductance discussed. Functioning of the circuit is described and test results and oscillograms shown. Major circuit components and their operation are explained. The facility may also be used without assistance from other sources for capacitance-switching tests up to 500 equivalent 3-phase module mvar (megavars). It is expected that this circuit will provide effective short-circuit testing for high megavolt-ampere breakers which is economically impractical by any other means.