Patent Application
20150309107
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1. Field of the Invention
The disclosure generally relates to electrical windings. More specifically, the disclosure relates to the detection of degradation of electrical windings for electromagnetic devices, such as solenoid coils, inductors, electromagnets, transformers, sensor coils, motors, and generators.
2. Description of the Related Art
An electromagnetic device typically includes an electrical winding. The winding is made of an electrical conductor such as a wire typically in the shape of a coil, such as a spiral or helix, to form a continuous series of winding turns.
Windings for the electromagnetic devices have an insulation layer of some type around the windings. The insulation is typically thin to allow for the close packing of the winding turns. The insulation can be a material with insulating properties that gradually degrade from various service conditions. As the winding insulation degrades, it eventually allows local exposure of the underlying conductor. If the insulation of the adjacent winding turns is intact, no shorting of turns occurs. However, if two or more exposed winding turns are adjacent to one another, the winding turns between the adjacent exposed conductors are shorted. Shorting of turns is progressive, eventually leading to winding failure.
Windings for electromagnetic devices, such as solenoids in solenoid-operated valves, are often scheduled for replacement at intervals far less than the average winding life, so that unexpected winding failures are reduced. Having knowledge of the health of the winding in an electromagnetic device is desirable to reduce both premature replacement and unexpected winding failures, each of which results in downtime of the process of which the electromagnetic device is a part. Windings in other electromagnetic devices are similarly situated. Thus, the principles apply to other applications using windings.
Some known systems disclose monitoring a solenoid health, such as U.S. Pat. No. 8,055,460. This patent discloses a method for monitoring the state of health (SOH) of a solenoid powered by a battery and includes measuring a voltage and a current supplied to the solenoid by the battery, using a processor to determine each of an equivalent resistance and inductance of the solenoid using the voltage and the current, comparing the equivalent resistance and the equivalent inductance to a corresponding calibrated threshold, and recording deviations from the corresponding calibrated thresholds as a pair of SOH values. A trend of the SOH values is continuously monitored, and an appropriate control action is taken when either SOH value drops below a calibrated lower limit. A solenoid monitoring system includes a solenoid, voltage and current sensors, and a controller having an algorithm for continuously monitoring a state of health of the solenoid. In general, U.S. Pat. No. 8,055,460 teaches measuring voltage from a battery supplying power to the circuit, a current, and resistance in the circuit together with a time constant, to calculate an equivalent inductance and equivalent resistance in the circuit. These calculated values can be compared with a known “good” solenoid having a nominal or calibrated value for inductance and resistance as reference values to indicate the condition of the solenoid in question, and apparent cause of a failure such as an open circuit or a shorted winding turn in the solenoid.
However, the inventors of the present disclosure have realized that measuring voltage, resistance, or current parameters and mapping changes does not yield sufficient sensitivity to determine a failing electrical winding. Therefore, despite some efforts in the field, such as those found in the above exemplary US patent, for determining a failing electrical winding, there remains then a need for improved detection of the health of a winding.
The present disclosure provides a method and system for measuring an increase in wattage to detect a potential winding failure. The increase in watts in the winding occurs when a time-varying magnetic field from active turns of the winding induces a time-varying current on shorted turns of the winding. The resistance through the shorted turns and the induced current result in power usage and increased watts. The wattage increase is much greater than a resistance decrease in the winding by the shorted turns. Measuring the watts results in detecting a shorting winding with greater sensitivity than measuring the resistance. In one embodiment, the winding can be tested offline with a wattmeter and power supply. In another embodiment, the winding in use and its wattage can be monitored continuously or periodically locally or remotely, with an optional sensor to initiate a signal upon reaching a certain percentage increase in watts.
The disclosure provides a method of measuring the health of an electrical winding for an electromagnetic device, the method comprising: applying a time-varying voltage to an electrical winding having a plurality of winding turns; measuring a wattage of the winding; comparing the measured wattage of the winding to a predetermined reference wattage for the winding; and determining if the measured wattage is greater than the reference wattage to indicate one or more shorted winding turns in the winding. The method further provides wherein the one or more shorted winding turns creates an induced current, and wherein measuring the wattage comprises measuring the wattage of the induced current of the shorted winding turns.
The disclosure provides a system for measuring the health of an electrical winding, comprising: an electrical winding having a plurality of winding turns; a power supply coupled to the winding for providing a time-varying voltage to the winding; and a wattmeter coupled to the winding. The present invention further provides wherein a shorted winding turn creates an induced current in the winding and wherein the wattmeter measures a wattage, including wattage from the induced current, for reference to a reference wattage for the winding, the reference wattage being for an electrical winding in a predetermined condition.
The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicant has invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present disclosure will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. The use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims. Where appropriate, one or more elements may have been labeled with an “A” or “B” to designate various members of a given class of an element. When referring generally to such elements, the number without the letter is used. Further, such designations do not limit the number of members that can be used for that function.
The present disclosure provides a method and system for measuring an increase in wattage to detect a potential winding failure. The increase in watts in the winding occurs when a time-varying magnetic field from active turns of the winding induces a time-varying current on shorted turns of the winding. The resistance through the shorted turns and the induced current result in power usage and increased watts. The wattage increase is much greater than a resistance decrease in the winding by the shorted turns. Measuring the watts results in detecting a shorting winding with greater sensitivity than measuring the resistance. In one embodiment, the winding can be tested offline with a wattmeter and power supply. In another embodiment, the winding in use and its wattage can be monitored continuously or periodically locally or remotely, with an optional sensor to initiate a signal upon reaching a certain percentage increase in watts.
Measurement of the wattage between the lead 10 (at the effective position of lead 10′) and 12 can schematically be considered the sum of the winding current IC through the winding resistance Rc and the induced current IS through the shorted turns resistance Rs. The shorted turns 20 result in a measurable additional wattage at a much higher rate than the reduction in resistance in RC to account for the resistance RS of the shorted turns. Thus, monitoring wattage can be effectively used to detect small numbers of shorted turns, thereby allowing an improved prediction of a future failure of an electrical winding. As described in
In operation, the wattmeter can be attached to the electrical winding to measure its condition. A power supply directly or through the wattmeter can provide current to the winding. It is envisioned that a standard winding will have a predetermined acceptable wattage as reference wattage. Any future measurements of similar windings can be compared with the reference wattage. When the winding is removed from operation for a health test, any increase in the wattage can indicate a degradation of the insulation, one or more shorted turns, and the increased potential for winding failure. Alternatively, the winding can remain in operation and a wattmeter be used to measure the condition of the winding turns during operation. Thus, a decision can be made on replacement of the winding prior to its expected approaching failure. Periodic or continuous monitoring of the health of the winding can be used to indicate when an electrical winding is approaching the end of its useful life and needs replacement. For DC circuits operating the winding, a time-varying signal can be imposed when the winding is offline, or superimposed over the DC signal so that a wattmeter can measure the wattage including wattage from an induced current in the shorted turns from the superimposed time-varying signal. The wattage can be monitored and sensed for certain threshold levels.
The various methods and embodiments of the system can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa. References to at least one item followed by a reference to the item may include one or more items. Also, various aspects of the embodiments could be used in conjunction with each other to accomplish the understood goals of the disclosure. Unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising,” should be understood to imply the inclusion of at least the stated element or step or group of elements or steps or equivalents thereof, and not the exclusion of a greater numerical quantity or any other element or step or group of elements or steps or equivalents thereof. The device or system may be used in a number of directions and orientations. The term “coupled,” “coupling,” “coupler,” and like terms are used broadly herein and may include any method or device for securing, binding, bonding, fastening, attaching, joining, inserting therein, forming thereon or therein, communicating, or otherwise associating, for example, mechanically, magnetically, electrically, chemically, operably, directly or indirectly with intermediate elements, one or more pieces of members together and may further include without limitation integrally forming one functional member with another in a unity fashion. The coupling may occur in any direction, including rotationally.
The order of steps can occur in a variety of sequences, unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions.
The invention has been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicant, but rather, in conformity with the patent laws, Applicant intends to protect fully all such modifications and improvements that come within the scope or range of equivalent of the following claims.
