Abstract: A power transformer having a magnetic core winding assembly disposed within a casing, which contains multiple sensing means to sense abnormalities in fault conditions of the transformer, and an annunciator, having electro-mechanical relay circuits responsive to the sensing means for energizing an alarm circuit. The electromechanical relay circuits are arranged to provide two or more alarm point indication circuits, a pulse circuit and a bistable switching circuit adapted to energize external protective apparatus. The pulse circuit translates one or more sensing means signals of undetermined duration to a single "pulse" signal of predetermined duration. This pulse signal is used to control a switching circuit with a contact connected to operate external protective devices such as an audible alarm. The pulse circuit provides for isolation of the indication circuits from the switching circuit such that each may be reset independently of one another.

Abstract: The present power supply has two step-up transformers with their respective primary and secondary windings series-connected. A half-wave rectifier tube and a filter are connected to the transformer secondary windings to rectify the current induced in them and to smooth out fluctuations in that current. One or more additional step-down transformers are provided, each having a primary winding that may be switched in series with the first-mentioned primary windings or disconnected from them and a secondary winding connected across a lamp. These additional transformers, when connected in the circuit, reduce the D.C. output voltage of the power supply and enable this output voltage to be selectively adjusted in steps. The lamps indicate visually which of these additional transformers are connected in the circuit.

Abstract: A housing, a first elongated generally cylindrical member fixed to the housing and having an open end which is adapted to be in open communication with the interior of the sealed transformer casing; this first member also has at least a portion of its length composed of transparent material for viewing the interior. Means, such as a float, are contained in the first cylindrical member for providing a visual indication of the gas emission levels. Additional means are coupled to and communicate with the first cylindrical member for measuring gas emission levels in the transformer and for measuring variations in the internal pressure of the transformer casing. A second generally cylindrical member is fixed to the housing and has one end adapted to extend into the sealed transformer casing. This second member includes means, such as temperature sensors, for detecting changes in the temperature of the dielectric in the transformer casing.

Abstract: A primary and a secondary of an inductive position sensor are connected by a capacitively coupling means. An output of the position sensor is connected to a level detector functioning as a failure indicator. The capacitive coupling of the primary and secondary of the inductive position sensor results in the output of the position sensor being above a minimum signal level at every position including the position at which the sensor output indicates zero or null position. When the sensor output falls below the minimum signal level, the level detector indicates failure.

Abstract: The system for determining and indicating overload conditions of electrical apparatus immersed to a dielectric liquid contains a heat sensing element in the top portion of the dielectric liquid and a load current sensor. The output signal of the heat sensing element and the output signal of the load current sensor, corrected with due regard to the dependence of the temperature of the winding's hottest spot on the load current, are applied to a switching circuit. The switching circuit contains an alarm circuit and a tripping circuit controlled by low- and high-overload threshold elements selectively operating at successively increasing temperature values of the electrical apparatus' hottest spot. The tripping circuit comprises a device for suppling an alarm signal and/or for deenergizing the electrical apparatus upon completion of the safe service life of the electrical apparatus.

Abstract: A fluid-filled electrical bushing for connecting an electrical conductor in a fluid-filled transformer to an electrical conductor in another enclosure. The electrical bushing includes a safety device consisting of two coaxial flexible capsules which are joined to a plate disposed therebetween and which respectively communicate with the dielectric fluid in the bushing and with the dielectric fluid in the transformer. The plate, which is movable in opposite axial directions in response to the pressure difference between the dielectric fluid in the bushing and the dielectric fluid in the transformer acting thereon, alternately engages first or second electrical contacts to complete an electrical circuit indicating an over-pressure condition caused by internal arcing, or the abnormal expansion or an insufficient amount of dielectric fluid within the bushing.