Abstract: Monitoring the condition of an electrical apparatus based on an estimated temperature of a conductor in the electrical apparatus, including receiving a measured temperature value from a first thermal sensor disposed in the electrical apparatus and configured to sense temperature at a location separated from the conductor by an insulator, generating an estimated conductor temperature value based on applying a non-linear model to the measured temperature value, and monitoring the condition of the electrical apparatus based on the estimated conductor temperature. The non-linear model may include a Hammerstein Wiener model.

Abstract: A capacitive voltage sensor apparatus including an electrically insulating body, an elongated conductor embedded at least partially in the insulating body, a first floating sensor electrode embedded in the insulating body and capacitively coupled to the elongated conductor and configured to provide a first output representing the voltage of the elongated conductor, and a second floating sensor electrode embedded in the insulating body and capacitively coupled to the elongated conductor and configured both to provide a second output representing the voltage of the elongated conductor and to shield the first floating sensor electrode from electric fields that may originate from sources external to the capacitive voltage sensor apparatus. A capacitor may be embedded in the insulating body and electrically connected with the first electrical sensor to form a capacitive voltage divider that provides the first output.

Abstract: Monitoring the condition of an electrical apparatus based on an estimated temperature of a conductor in the electrical apparatus, including receiving a measured temperature value from a first thermal sensor disposed in the electrical apparatus and configured to sense temperature at a location separated from the conductor by an insulator, generating an estimated conductor temperature value based on applying a non-linear model to the measured temperature value, and monitoring the condition of the electrical apparatus based on the estimated conductor temperature. The non-linear model may include a Hammerstein Wiener model.

Abstract: A capacitive voltage sensor apparatus including an electrically insulating body, an elongated conductor embedded at least partially in the insulating body, a first floating sensor electrode embedded in the insulating body and capacitively coupled to the elongated conductor and configured to provide a first output representing the voltage of the elongated conductor, and a second floating sensor electrode embedded in the insulating body and capacitively coupled to the elongated conductor and configured both to provide a second output representing the voltage of the elongated conductor and to shield the first floating sensor electrode from electric fields that may originate from sources external to the capacitive voltage sensor apparatus. A capacitor may be embedded in the insulating body and electrically connected with the first electrical sensor to form a capacitive voltage divider that provides the first output.