T-Star's static [solid state] capacitor switches provide sub-cycle response, the Relability to re-switch in a cycle, and the ability to switch billions of times without showing any wear or timing changes.  The development of a design reliably hardened against mishaps that can occur on the medium voltage took lots of work, time and field experience, and proved the following features:  

  • Protection against electromagnetic interference
  • High Reliabilty Electronic components
  • Precise firing function with dV/dt independence
  • Two-stage hardware/software interlock to prevent false (mis) firing.
  • Thyristor status monitor – including indication of protective firing
  • Improved dV/dt capability
  • RC damping and DC sharing resistors
  • Reliable magnetically coupled thyristor triggering technology
  • Valve reactors to limit di/dt stress during turn on and dv/dt during transients in the off state.
  • N+1 and N+2 designs for reliable operation, high redundancy factors and low thyristor voltage stress.
  • Non-PCB oil cooled and insulated design
  • Average annual failure rate of less than 0.15%

Static switches are for 50/60 Hertz operation.


One model variant is for use at 4-8 kV delta or 11-15 kV neutral-grounded wye.



One model variant is for use in 15 kV delta/ 23 kV wye systems