Current zero (CZ) refers to the interruption phenomena in high power circuit-breakers. Today it seems improbable that high voltage circuits could be interrupted economically by other means than the electric arc.
All circuit-breakers are working based on contact moving away from each other, thus creating an electrical arc between the contacts. The current zero phenomena is an indicator for the pressure, temperature, ion density, plasma flow, etc. Current zero measurements are used to understand the phenomena of the arc and to identify the dominant parameters for a successful interruption of the current.
Hardware requirements for current zero testing
To use fibre isolated digitizer technology for current zero testing, mainly 4 requirements need to be met:
- vertical resolution
- immunity against fast transients
- immunity agains magnetic fields
Acceptance tested 6600 HV for current zero application
The test was performed at the KEMA High Power lab in Arnhem in the Netherlands, one of the leading experts in terms of High Power testing. Given the absence of standards and generally accepted calibration methods against which to test, KEMA decided to set up a dedicated test program, based on experience gained in ten years of current zero measurements.