Apparatus and method for cooling power transformers
AssigneeAdvanced Power Technologies, LLC
InventorsGary R. Hoffman, Jeffrey Anderson
Life of this patent
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Abstract
The cooling system for a power transformer is activated by sensing and processing the frequency characteristic including the harmonic contents, of the inrush current into the transformer, when the transformer is first energized. The cooling system may include motors operating devices such as oil circulating pumps and fans causing a coolant to flow about the power transformer. The cooling system is deactivated by sensing when the transformer is de-energized and when its temperature is below a predetermined level.
Claims13
Apparatus for protecting a power transformer having a primary winding to which an operating voltage is selectively applied and having a secondary winding intended to be coupled to a load and wherein the power transformer is cooled by a coolant which is caused to flow about the transformer via at least one cooling device coupled to a motor, the protective apparatus comprising:
- means for sensing the application of an operating voltage to the power transformer including means for sensing an inrush current when the operating voltage is applied to the power transformer, said inrush current displaying frequency characteristics;
- means for processing the sensed inrush current and determining the presence and value of selected frequency characteristics of the inrush current;
- and
- means responsive to the frequency characteristics of the inrush current having a certain value indicative of the application of an operating voltage to the power transformer for turning-on the motor and causing the coolant to flow about the transformer.
A method for protecting a power transformer having a primary winding to which an operating voltage is selectively applied and having a secondary winding intended to be coupled to a load and wherein the power transformer is cooled by a coolant which is caused to flow about power the transformer via at least one controllable cooling device, the method comprising the steps of:
- sensing the inrush current in the power transformer at the moment when an operating voltage is first applied to the power transformer;
- processing the inrush current to determine the presence of selected harmonics;
- detecting the presence of selected harmonics having a predetermined value;
- and
- causing the coolant to flow about the power transformer when the value of selected harmonics exceed a predetermined value.
Apparatus for protecting a power transformer having a primary winding to which power is selectively applied and having a secondary winding intended to be coupled to a load and wherein the power transformer is cooled by a coolant which is caused to flow about the transformer, the protective apparatus comprising:
- means for sensing the application of power to the primary winding of the transformer including means for sensing the flow of current through the transformer when power is applied, which current is defined as the inrush current and said inrush current having a frequency characteristic;
- means for processing the frequency characteristic of the inrush current and determining the presence and value of significant characteristics of the inrush current;
- and
- means responsive to the frequency characteristic of the inrush current having a certain value for causing the coolant to flow about the transformer.
Dependencies are inferred from the claim text.