High voltage high-current commutator based on the series connected triggered vacuum switches

Summary form only given. The 80 kV, 250 kA commutator consisting of two series-connected triggered vacuum switches (of type TVS-43) has been manufactured and tested. The measurements have shown that the voltage distribution on series connected switches was non-uniform. During tests breakdown voltages of each TVS and the commutator breakdown voltage as a whole were measured. The experimental distribution function of breakdown voltage of the commutator was constructed on the basis of measurement results. The tests results have allowed to check the used method for breakdown probability account of the commutator, in which the experimental distribution function of breakdown voltage of each TVS is used. The comparison of a calculated distribution function of breakdown voltage of the commutator with the experimental distribution function showed good correspondence. The proposed method allowed to estimate dielectric strength of the commutator depending on the degree of non-uniformity of voltage distribution between series connected TVSs: (a) at uniform voltage distribution, (b) at light non-uniform voltage distribution, (c) at strong non-uniform voltage distribution. At uniform voltage distribution, in the field of small probability values which are used in practice, the commutator breakdown voltage is equal to the sum of breakdown voltages of TVSs, and with it the commutator breakdown probability does not exceed the sum of breakdown probabilities of TVSs. At light non-uniform voltage distribution (e.g. at division factor less than 1.2) as it takes place in the commutator model, dielectric strength of the commutator decreases only by 10% which makes the application of grading devices inexpedient.