Abstract: According to one embodiment an apparatus to monitor the temperature of a transformer is disclosed. The apparatus includes a fiber optic cable having a temperature sensing probe on one end embedded in windings of a transformer. An optical converter transmits light to the probe and receives light from the probe, and converts the light received to an electrical signal. The light received back from the probe is controlled by temperature of the probe. Monitors are used to monitor different parameters of the transformer. A controller generates a simulated winding temperature based on data received from the monitors and converts the electrical signal to a direct winding temperature. The controller analyzes the operation of the transformer by comparing the direct winding temperature to the simulated winding temperature. Other embodiments are disclosed herein.

Abstract: A pressure relief device for electrical equipment housing, includes a valve body having a pedestal that projects above a mounting flange and a table on the pedestal that supports a two-stage valve assembly that can be sized in diameter independently of the working area of the flange beneath the table. The design is particularly applicable to retrofit applications for large power distribution equipment with the footprint of the pressure relief device fixed by the design of the equipment housings. The first-stage valve opening can be sized substantially as large as vent openings in the housings and the second-stage valve openings can be sized in the desired relationship with the first-stage opening for optimizing valve performance independently of the constraints imposed by the footprint of the device.

Abstract: An enclosure for a pressure relief device, particularly pressure relief devices mounted on electrical equipment housings, is pre-assembled together with the pressure relief device. The enclosure, which provides for temporarily confining and directing fluids discharged from the pressure relief device, is pre-assembled leaving a clearance space so that the pressure relief device can be mounted on the housing with the enclosure system in place. A peripheral shield with an opening for attaching the enclosure to a discharge pipe or other duct work remains rotatable until deliberately secured in place. Components can be shared between the enclosure and the pressure relief device to provide a more efficient and cost effective design.

Abstract: A pressure relief device for electrical equipment housing, includes a valve body having a pedestal that projects above a mounting flange and a table on the pedestal that supports a two-stage valve assembly that can be sized in diameter independently of the working area of the flange beneath the table. The design is particularly applicable to retrofit applications for large power distribution equipment with the footprint of the pressure relief device fixed by the design of the equipment housings. The first-stage valve opening can be sized substantially as large as vent openings in the housings and the second-stage valve openings can be sized in the desired relationship with the first-stage opening for optimizing valve performance independently of the constraints imposed by the footprint of the device.

Abstract: An enclosure for a pressure relief device, particularly pressure relief devices mounted on electrical equipment housings, is pre-assembled together with the pressure relief device. The enclosure, which provides for temporarily confining and directing fluids discharged from the pressure relief device, is pre-assembled leaving a clearance space so that the pressure relief device can be mounted on the housing with the enclosure system in place. A peripheral shield with an opening for attaching the enclosure to a discharge pipe or other duct work remains rotatable until deliberately secured in place. Components can be shared between the enclosure and the pressure relief device to provide a more efficient and cost effective design.

Abstract: Disclosed is a pressure relief valve for attachment to a closed vessel having an opening to vent gas and liquids from the housing should the internal housing pressure rise to unacceptable levels. The pressure relief valve includes a single gasket that seals between a valve disk and a collar disposed about the opening. The gasket is fixed to the collar by a single retaining ring and effects seals with the disk valve in two planes, one seal is in a plane generally parallel to the plane of the opening and a second seal is in a plane generally normal to the plane of the opening. Moreover, the second seal remains in tact for a short time after the first seal is broken to permit the rapid separation of the disk valve from the gasket to vent gas and liquids from the housing.

Abstract: A shield for a pressure relief device for containing and deflecting released fluids is described. The shield includes an enclosure for surrounding the pressure relief device, the enclosure having a first port for engaging the enclosure to a relief duct while permitting the shield to be positioned in a necessary orientation on the device.

Abstract: A gasket assembly including a base having a central opening and a circular slot having an undercut portion extending around the central opening, a circular gasket positioned in the circular slot and having a tapered side located proximate the undercut portion, and cementitious sealant material abutting the tapered side of the gasket and in the undercut portion for retaining the gasket in the slot. The gasket assembly is especially useful for the seal for the pressure relief valve of an electrical power transformer.

Abstract: An electronic relay control circuit is provided for liquid cooled electric power transformers. The control circuit senses the rate of change of internal tank pressure and operates its relays in response to a sudden pressure increase. Relay control connections are provided for operating transformer trip and annunciator circuits. The relay response is field adjustable.

Abstract: A method and system is provided for electronically simulating, indicating and controlling the temperature of liquid cooled multi-phase electric power transformers. The temperatures of transformer windings are electronically computed from the actual top oil temperature and the computed incremental additional temperatures resulting from the transformer winding currents to determine the hottest spot temperature. The signals representative of the winding current for each phase of the multi-phase transformer are time processed to simulate the rate of rise of winding temperature resulting from those currents. A square-law function is generated to make a winding bias parameter for each winding. The signals representative of the actual and incremental additional temperature are added for each transformer phase and the largest signal, representative of the hottest winding is used to indicate and control the transformer temperature.

Abstract: A method and system for indicating and controlling the temperature of liquid cooled multi-phase power transformers. The winding temperatures of a transformer are electronically computed from the actual top oil temperature and the incremental additional temperatures resulting from the highest transformer load current to determine the hottest spot temperature. One curve from a family of curves representing the incremental temperature for various transformers may be selected or programmed by adjustments made which simulate the incremental additional temperature which results from transformer winding current. In this way the input current range, winding bias setpoint, winding bias curve, and time-constant can be chosen independently so that any electric power transformer may be simulated.

Abstract: A method and system for controlling the temperature of liquid cooled power transformers. The winding temperature of a transformer winding is electronically computed from the actual top oil temperature and the incremental additional temperature resulting from transformer load current. One curve from a family of curves representing the incremental temperature for various transformers may be selected or calibrated by adjustments made which simulate the incremental additional temperature which results from transformer winding current. The total temperature value resulting from the addition of both the top oil temperature and the incremental temperature are used to control indicators, cooling fans, circuit trips and retain an indication of the highest temperature occuring during the time period of interest.

Abstract: A method and apparatus is provided for computing the life expectancy of electrical power transformers by computing the used life of a transformer at a rate determined by the Arrhenius function of the temperature of the transformer device being monitored.

Abstract: A rotatable one-piece lens assembly that may be rotated relative to the instrument housing comprising a lens boss, integral with the lens, moving with the rotated lens to move the pointer to engage and test the switches. After the switch test the lens may then be rotated back to its normal position. In this manner the switches are tested without removing the lens from the instrument housing.

Abstract: An improvement in a pressure relief device of the type used in a power transformer, the improvement consisting of a flat circular gasket fixedly mounted about its inner periphery, and having its outer periphery flexibly arranged for wiping contact with the inner surface of a cup-like valve member.

Abstract: A pressure relief device for use on a liquid filled vessel, such as a power transformer having a coolant oil enclosed, which device includes a clamp arranged on the device so that the pressure relief function of the device is negated until the clamp is removed.

Abstract: A liquid level gauge calibration means which utilizes slip clutch action between the gauge pointer shaft and the float rod. In setting the gauge range, either of said elements may be held stationary at a given point while the other element is moved to coordinate with the given point. Upon release of the element being held, the slip clutch is effective to maintain the established relationship between the two elements. A tool is used to move the slip clutch as needed for desired relative setting of the two elements.

Abstract: A thermometer unit for monitoring the temperature of a fluid cooled electric transformer, the unit having a ceramic body insertable between the coils of the transformer winding immersed in cooling fluid in the transformer case. A nylon element responsive to heat changes is confined in the interior of the body and is adapted to expand according to developing heat changes. A flexible tubing having a loop portion fronting a tapered end of the nylon element is filled with a fluid which is caused to oscillate in the tubing accordingly as a rocker arm alternate actuates a pair of associated bellows. As the nylon element expands in response to a temperature rise, it squeezes the tubing causing a load to be placed upon the rocker arm which is indicative of the corresponding temperature change.