Jolanta Sadura
supervisor: Jan Sroka
Does in situations where the high precision and reliability is required, uncontrolled operation of the control equipment can happen? The High Current Laboratory conducts research and development works covering in particular studies of switchgear, transformer stations, earthing, connectors, etc. One of the tests is the short circuit test which is always preceded with powering MV side of the test transformer by unloaded LV side. Thereafter the controller must wait for release of the operator to start the test. Sometimes electromagnetically disturbed controller starts the test without release. Such situation is undesired and can be destructive for the device under test. Identification of the transient fields during powering the test transformer is indispensable by assessing hazard of EM interference of the controller.
The beginning investigation gave the hint that repetitive damped oscillatory waves DOW are component of electromagnetic environment. For identification of the problem instrumentation such as D-dot and B-dot field probes were used. The poster shows results of field measurements along with recording the voltage signals at the gates of controller. It was suspected that repetitive ignition and extinction of the short arc by closing the circuit breaker in the MV circuit is origin of the DOW. Additional investigation of the circuit breaker in stand-alone operation exclude this hypothesis. The only possibility of the DOW is pulse travelling forth and back in the MV circuit which can happen in lines with distributed parameters.
Presented investigations expands the scope of electromagnetic phenomena present in the High Current Laboratory. All information about existing disturbances and their sources are used as main and basic information for prototyping new control equipment working in such an unfriendly environment.