Fast Commutation of DC Current into a Capacitor Using Moving Contacts

Dragan Jovcic* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)
7 Downloads (Pure)


The article describes a method of fast commutation of DC current into a capacitor. Theoretical study is provided which enables evaluation of commutating DC current for the given contact velocity, capacitance and dielectric strength. It is concluded that a non-zero contact velocity at separation is required, and a corresponding switch design is proposed.

Experimental results on a laboratory set up illustrate successful DC current commutation up to 400 A, with voltages rising to 1.3 kV. Further experiments demonstrate that parasitic parameters reduce the magnitude of the current that can be commutated.

A detailed non-linear PSCAD model and a linear model for the parasitic circuit are presented to enable prediction of the success of commutation. The model accuracy is confirmed with experimental tests.

The DC current commutation in the proposed method occurs 5-10 µs after the contact separation, which is much faster than with other methods employing moving contacts. A further benefit of the extremely short arcing is elimination of thermal issues on contacts, and possible simplified design of the mechanical switch.
Original languageEnglish
Pages (from-to)639-646
Number of pages8
JournalIEEE Transactions on Power Delivery
Issue number2
Early online date4 Jun 2019
Publication statusPublished - Apr 2020

Bibliographical note

The author is thankful to Mr R. Osborne from University of Aberdeen for help with the experimental studies.


  • DC switchgear
  • HVDC protection
  • DC circuit breakers
  • Capacitors
  • Switches
  • Electrodes
  • Circuit breakers
  • Contacts
  • Current measurement
  • Capacitance


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