Abstract: An electrical transformer includes a tank containing transformer fluid and a transformer core and winding subassembly located in the transformer fluid within the tank. The electrical transformer also includes a mechanism for varying the dynamic pressure of the transformer fluid within the tank during electromagnetic operation of the transformer core and winding subassembly to cancel out (or reduce) noise-causing vibrations in the transformer fluid which come from the operating transformer core and winding subassembly. Preferably, the electrical transformer further includes an active mount subassembly.

Abstract: An electrical transformer includes a housing, a transformer core and winding subassembly located within the housing, and an active mount subassembly having an active mount and a controller. The active mount has a first end attached to the housing and a second end attached to the transformer core and winding subassembly. The controller has an output port connected to the active mount. The active mount cancels out (or reduces) noise-causing vibrations which come from the transformer core and winding subassembly during transformer operation.

Abstract: An electrical transformer includes a housing, a transformer core and winding subassembly located in the housing, and a cooling fan subassembly. The cooling fan subassembly includes a variable speed fan located outside the housing, a temperature sensor located near the housing, and a controller having an output port connected to the variable speed fan and an input port connected to the temperature sensor. The controller reduces the fan speed (and hence the fan noise) when a lower fan speed can maintain the desired temperature as sensed by the temperature sensor. Preferably, the electrical transformer further includes an active mount subassembly and/or (when the housing includes a tank containing transformer fluid) a mechanism for varying the dynamic pressure of such transformer fluid.