Rough identification of EM disturbances interfering the time-phase controller by the short circuit tests

The short circuit tests are always preceded with powering the primary side of the test transformer by unloaded secondary side. Thereafter the time-phase controller must wait for release of the operator to start the test. Sometimes controller is interfered and 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 time-phase controller. The first trial of identification is presented in this paper. It gave the hint that repetitive damped oscillatory waves can cause malfunctioning of the controller. Origin of them is repetitive ignition and extinction of the arc by closing the the circuit breaker in the medium voltage circuit. Measurements of E and H fields with adequate instrumentation will be repeated. Also nature of the phenomenon will be studied in details in the future.