Abstract: A variable sensitivity monitor circuit changes sensitivity for a period immediately following startup or turnon of the process or equipment being monitored. By changing sensitivity, the monitor circuit will not respond to the transient produced at startup or turnon but will respond to any abnormal condition greater than the transient without any decrease in response time of the monitor circuit.

Abstract: An electronic circuit is disclosed that provides a delay of operation until a piece of equipment reaches operating temperature. The circuit automatically adjusts the delay time to provide only the time necessary for warmup should there be a short outage of line power causing only partial cooling of the equipment. By proportioning the warmup delay time to the time of power loss, the equipment outage can be minimized. The proportionality between the warmup delay time and the time of power loss can be either linear or non-linear depending on the specific application.

Abstract: A thin wall, stainless steel transformer case of rectangular box configuration is comprised of edge welded steel plates with its sidewalls and end walls bearing vertical, U-shaped bonded channel members of copper for mechanical reinforcement of the case and for forming transformer heat dissipating fins. Stainless steel reinforcing channel members are similarly bonded to the outside of the case bottom wall and the cover. An epoxy fiberglass strap spanning interiorly between the sidewalls of the case at its upper end and bolted to opposed brackets press the transformer core against the bottom wall of the transformer case. A pair of deformable tubes sealably project through the cover for effecting vacuum evacuation of the interior with the cover sealed to the case and for feeding insulating dielectric liquid to the transformer case interior. The tubes are pinched off and sealed after filling.

Abstract: An automatic recycle circuit is disclosed for use in a process or apparatus of the type wherein process or equipment conditions are monitored to detect an abnormal condition. The automatic recycle circuit accepts inputs from monitor circuits which are intended to cause recycle operation and monitor circuits which are intended to cause complete shutdown and reacts appropriately to each type of input. With respect to those inputs from monitor circuits which are intended to cause recycle action, the automatic recycle circuit is capable of permanently shutting down the process or apparatus if the detected abnormal condition has a duration exceeding a first predetermined time or abnormal conditions are detected a predetermined number of times within a second predetermined time period.