Model-Based Testing of Instrument Transformers Utilizing Impulse Response Measurements

Instrument transformers are crucial for ensuring a reliable and safe energy grid. To achieve high-quality production, proper installation, post-transport functionality checks, and maintenance are essential. For that purpose tests are required. One standard testing method involves measuring and determining the parameters of the equivalent circuit diagram at various frequencies. The usual approach employs a frequency sweep, wherein a sinusoidal voltage signal is applied to the low-voltage side of the transformer. Current signals are then measured while the high-voltage side is either in open-circuit or in short-circuit. This process is repeated for each frequency. However, this method can be costly, particularly during maintenance in the field, as it necessitates expensive measurement equipment and multiple measurements to obtain parameters for each frequency. This paper introduces an alternative method for testing instrument transformers using impulse response measurements. This approach enables the determination of parameters for all frequencies in a single measurement.