Magnetization of a Current Transformer (CT) is a non-linear characteristic, which can cause distortion in its secondary waveform, causing malfunction of protective relay. In this paper, two algorithms based on mathematical morphology, morphological gradient and improved morphological gradient have been compared for detection of CT saturation. The improved morphological gradient is effective in removing noise and separating transient information from the signal. Starting and end time of saturation can be detected using this algorithm.

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