A Safety Case for the Use of Bipolar +-60V DC for Microgrids - Raw Arcing Data
The data herein forms part of the work, 'A Safety Case for the Use of Bipolar ±60V DC for Microgrids'. The application of entirely DC systems for PV microgrids are gaining proliferation as they do not require inefficient conversion between AC & DC. However, the application of DC for power distribution increases the likelihood of series arcs. In the case of AC distribution, series arcs are generally extinguished as the voltage crosses 0V. As this does not occur with DC distribution, series arcs tend to sustain resulting in heating, damage and potentially fires.
In order to test an arc detection and extinguishing algorithm, a laboratory experiment was set up to simulate a break in the intended path of current of a 120V DC circuit. Whilst current is flowing in the circuit, an opening can be created in the conducting path using a pair of brass electrodes, drawn apart in a controlled and repeatable manner by means of a precision stepper motor. The electrodes are mounted in a frame to allow separation in one axis. One electrode is held in place while the other is mounted on a stepper motor shaft. The voltage across the arc gap is recorded using an oscilloscope and two voltage probes in differential arrangement.
An arc is formed in the gap upon initial separation. The opening of the gap represents a longitudinal break in the conductive path of a DC microgrid feeder. The stepper motor driver is controlled by a microcontroller, programmed to govern the velocity and final separation distance of the electrodes. A series arc is then established in the opening between the electrodes. This experimental set up for arc testing, commonly referred to as the ‘pull apart’ method conforms with the standard UL1699B for testing arc fault detectors in PV systems.
The file name represents the separation in mm and the speed of separation (FS - Full speed, HS - Half speed), however the exact speed of separation was not recorded. Column A represents time (s). The values of columns B & C represent the voltages measured on the two channels (A & B) of an oscilloscope. The data is also presented in pico-scope data file format.
For further information and results analysis please refer to 'A Safety Case for the Use of Bipolar ±60V DC for Microgrids' available through IEEE Access.
