Project-Management
| Name | Working area(s) | Contact | |
|---|---|---|---|
| Manuel Philipp M.Sc. Investigation of the switching behavior of a model vacuum switch under direct current load with different contact geometries | manuel.philipp@tu-... +49 6151 16-20449 S3|21 405 |
Project description
Background
In the course of network expansion and with the constantly growing demands on the power grid, meshed DC networks will become increasingly relevant in the future. In order to safely disconnect these direct current connections, circuit breakers are required that can switch DC currents quickly and reliably in case of a fault. Since, unlike alternating currents, there is no natural zero crossing of current in direct currents, conventional circuit breakers cannot be easily adopted for this application. In particular, due to the rapidly increasing current, this poses a critical scenario in the event of a fault. Vacuum circuit breakers have been reliably used as circuit breakers in our power grid at the medium-voltage level for decades. With vacuum as the insulating medium, they are considered “environmentally friendly” equipment and therefore provide an attractive basis for research on DC circuit breakers. Since the contact geometries of the electrodes in commercial vacuum interrupters were designed for switching currents with a natural zero crossing, they need to be examined in terms of their switching behavior with DC currents.
Test Setup
To simulate direct current, the synthetic test facility of the high voltage laboratory at TU Darmstadt is employed. This facility generates a trapezoidal current pulse in the variable kiloampere range, which can be considered as DC current (2% ripple) for a duration of 7 ms.
As a direct current switching module, a model vacuum switch is utilized, incorporating switching contacts from commercial AC vacuum interrupters. Energy-absorbing arrester stacks are connected in parallel to this switch, along with a commutation path consisting of an RLC resonant circuit. During a switching test, the pre-charged capacitor of the resonant circuit is then discharged into the main current path through a thyristor switch to create a current zero crossing that can be switched by the DC switching module. Through observation windows at the level of the contacts, it is now possible to visually examine various phenomena during a switching test using a high-speed camera.
