Abstract: A pressure sensitive device includes a ring having a central axis, first side and second side. The ring includes a dielectric portion parallel to the central axis and between the first and second sides. A flexible membrane is connected to a periphery of the ring on the first side, the flexible membrane including a conductive portion. A perforated membrane is connected to a periphery of the ring on the second side. The perforated membrane is spaced apart and electrically isolated from the flexible membrane by the ring below a threshold pressure differential across the pressure sensitive device. The perforated membrane includes an opening therethrough and a conductive portion facing and corresponding to the conductive portion of the flexible membrane such that a threshold pressure differential across the pressure sensitive device causes deflection between the conductive portions of the flexible membrane and the perforated membrane to change an electrical property.

Abstract: A pressure sensitive device includes a ring having a central axis, first side and second side. The ring includes a dielectric portion parallel to the central axis and between the first and second sides. A flexible membrane is connected to a periphery of the ring on the first side, the flexible membrane including a conductive portion. A perforated membrane is connected to a periphery of the ring on the second side. The perforated membrane is spaced apart and electrically isolated from the flexible membrane by the ring below a threshold pressure differential across the pressure sensitive device. The perforated membrane includes an opening therethrough and a conductive portion facing and corresponding to the conductive portion of the flexible membrane such that a threshold pressure differential across the pressure sensitive device causes deflection between the conductive portions of the flexible membrane and the perforated membrane to change an electrical property.

Abstract: A method for evaluating the accuracy of a current transformer is presented. The current transformer has a primary winding and a secondary winding. A current is not circulated through the primary winding. A load is disconnected from the current transformer. A load impedance is measured of an internal instrumentation associated with the current transformer. The resistance in the secondary winding of the current transformer is determined. The load impedance is compared to a standard burden. A standard burden value is selected. The secondary voltage for a rated current is determined. The injection voltage is adjusted to the value of the secondary voltage. The exciting current and power are measured. The ratio error or the phase angle are then calculated by using the exciting current and power.