MXPA99002292A - Electrical contact wear and temperature indicator - Google Patents

Abstract

The design of electrical switches that operate under load (with current flowing) requiresreplacement of the electrical contact after erosion and wear experienced by arcing and raised temperatures reduce functionality below acceptable limits. A quantity of trace element or compound (18) is implanted at a depth representative of the point at which wear or erosion requires contact replacement. When exposed by wear or erosion, the quantity of the trace element (18) is released into the oil or other medium surrounding the contact, providing an indication of excessive wear. Alternatively or in addition, a quantity of indicator material is released from the surface of one or more switch components into the surrounding medium once a preselected temperature has been reached.

Description

INDICATOR OF WEAR AND TEMPERATURE. IN ELECTRICAL CONTACTS FIELD OF THE INVENTION The present invention relates in general to electrical switches and in particular to electrical contact assemblies of electric switches that use them.

- BACKGROUND OF THE INVENTION Electrical switch contacts operating under load typically wear out during normal operation and deteriorate further when overheating occurs. The wear and overheating of the contacts can cause faults or deteriorated operation of the switches and reduce or otherwise limit in general the service life of the switches themselves. The degree of wear or deterioration due to overheating is a function of the various conditions that exist during the operation, such as the amount of current conducted by the contacts, the voltage applied through the contacts, the maximum operating temperature experienced, together with the service security to which the contacts operate (for example, the amount and frequency of switching operations). In addition, the wear or overheating of the electrical contacts can be a sign of failure or malfunction of other components of the switches. The wear of electrical contacts is very common from the formation of electric arc that occurs whenever a switch interrupts a circuit. A voltaic arc is formed according to the electrical contacts are separated from each other and the electrical potential between them makes the electrons bridge in the region of the space between the contacts. A current is maintained in the electric arc until the spacing between the contacts, and therefore the impedance, increases sufficiently to prevent the electrons from bridging in the range for the given voltage potential. The current flowing through the gap generates heat, causing temperatures high enough to burn out part of the contact material. The switches can fail when the contacts have been so worn that they can not effectively complete a circuit. The switches are also subject to overheating by a highly resistive contact interface. Excessive heating of the contacts or other components of the switches can change the physical characteristics of the contacts less drastically than wear, but can nonetheless cause significant contact deterioration and even long-term contact failure. Among other things, overheating can cause the contacts to become brittle and / or excessively carbonized which can cause a type of fault known as a "current jump" fault within the commutator. The electrical contacts have a useful life that is related to the degree of wear or overheating, if this occurs. Once the contact has worn to the point at which additional use exposes the personnel or machinery to damage, known as the "critical point", the contact's useful life is terminated. The critical point is a measurement of volume and is reached when, as a result of wear for example, only a predetermined percentage of a contact remains. Since arc formation and wear can not be eliminated, the switches are often designed to allow contact replacement. It is typically less expensive to replace worn contacts than to replace an entire switch when the contact has worn to or near the critical point. With the results, however, switch users must monitor contact wear to recognize when they are approaching or have reached the predetermined critical point. It is important to replace worn contacts at or before the critical point, because contacts worn beyond that point continue to wear out and may cause the switch to fail. A switch failure can have a negative or catastrophic effect and represents a danger to personnel. On the other hand, the replacement of contacts before the end of his life increases the costs of material and work. The monitoring of the temperature to which the components have been subjected is also helpful in assessing the efficiency of the operation and the remaining useful life of the components, such as switch contacts, even before a fault occurs such as a " current jump ". There are four basic environments within which electrical contacts operate: (1) in air, (2) in inert gas, (3) under oil, and (4) in a vacuum. Each of these environments represents challenges for the contact monitoring procedure. The contacts in the air environment can be observed visually to monitor the degree of wear, allowing replacement at appropriate times for the life of the contact, before the risk of failure is exceedingly large. The contacts in the environment of inert gas and vacuum environment can not usually be observed visually, since they are very often contained in an opaque receptacle or a vacuum bottle. The contacts in oil medium are used for medium and high voltage equipment, including circuit breakers and load tap changers in transformers and regulators used by electric utility companies. These contacts operate under oil in a closed tank or compartment, preventing easy access to contacts. Regardless of the type of environment in which the contacts and other components operate, they can be operated in some form of receptacle. For air or oil environments, this receptacle may be open to the atmosphere, but for vacuum or inert gas environments, the receptacle must be sealed, making sealed receptacles particularly difficult to monitor. A transformer has two sets of wire coil, known as the primary windings and the secondary windings. A voltage applied to the primary windings (known as the primary voltage) will induce a voltage in the secondary windings (known as the secondary voltage). The secondary voltage will be higher or lower than the primary voltage, depending on the ratio of the number of turns, or spirals, of wire in the primary and secondary windings of the transformer. A transformer with a larger number of turns in the secondary windings will produce a secondary voltage higher than the primary voltage. A transformer without bypasses in the secondary windings will produce only a secondary voltage for each primary voltage. Many examples of transformers have numerous "branches", or access points, in the secondary windings, so that a variety of secondary voltages of a transformer can be selected. A transformer that has bypasses in the secondary windings will allow access to several secondary windings, depending on which branch is selected. A transformer can be used to both decrease and increase the voltage, if it is derived in points lower or higher in number than the number of turns in the primary windings. However, known means such as "coil branch selector switch" or "load variation changers" for the switch between the various branches of the secondary winding must be provided. A "charge bypass changer" is a mechanical device that moves an electrical contact to different leads within the transformer or regulator, depending on the required voltage output. In some designs, the electrical contact moves while the current is still flowing inside the transformer or regulator, creating numerous cases of arc formation through the contacts of the load tap changer as it moves from a tap position to the following. In other designs, a transfer switch is used to transfer the current during switching. In this case, the transfer switch uses a large sacrificial contact that is designed to perform the function of closing and opening the current, and the arc formation occurs over the sacrificial contact. There is a large expense associated with closing and opening these types of equipment to determine the degree of contact wear. This expense is composed of the need to extract, store and process a large amount of oil, sometimes up to 3785 liters. Contacts are often replaced prematurely due to the difficulty of predicting the wear ratio of one maintenance cycle to the next. The expense of inspecting contacts is often so great that maintenance departments invariably change contacts during each inspection, even if contacts have months or more of remaining service life. Properly matching the timely completion of the inspection with the change in the useful life of the contacts would advantageously result in cost savings. Some of the previously used means to monitor the performance of electrical equipment which sought to overcome the effort and expenses required by direct physical inspection includes the following: 1. Dissolved gas analysis (AGD) The analysis of dissolved gas in an oil environment is used. In the AGD, a sample of the oil surrounding the contacts is extracted and analyzed to monitor the dissolved gases. The presence of dissolved gases is indicative of several types of problems that may be occurring within the equipment. For example, the presence of acetylene dissolved in the vicinity of the oil is indicative of the failure of the nuclei in the transformers. This procedure lacks the precision necessary to determine the appropriate timely completion of the contact replacement, since the presence of gas is neither directly related to the amount of wear of the contacts nor is it an indication of the degree of heating of the contacts. 2. Infrared monitoring Infrared monitoring can be used in an air, inert gas, vacuum or oil environment. In infrared monitoring, an infrared camera is used to monitor the temperature of high-voltage equipment. The temperature and resistance are directly related. As the resistance to current flow increases through the electrical equipment, the temperature of the equipment and its surroundings also increases. The infrared camera measures the temperature increases in a general sense and alerts the user accordingly. However, this system is insufficient because it does not measure wear and tear and is not accurate enough to monitor the temperature of contacts or other components separately from nearby components within the receptacle. There exists, according to the above, the need to provide a wear indicator of the heating in electrical contacts which automatically monitors the contacts and provides an indication to the users that the critical point has been reached at one or more temperatures.

BRIEF DESCRIPTION OF THE INVENTION This invention is an assembly of contacts that includes means for indicating the wear and / or heating of electrical contacts operating in an environment of oil, air, inert gas or vacuum. The assembly includes a contact in which an implant that contains a wear or temperature indicator has been installed. The wear indicator is positioned as an implant at a depth corresponding to the critical point of the contact, beyond which additional wear makes contact inappropriate for use. When contact and implantation have worn to the critical point, the wear indicator is exposed or released to the surrounding environment where it can be detected. Alternatively or in addition to the wear indicator, a temperature indicator is connected to the contact or to the side inside a cavity or opening in the surface of the contact or other component. The indicator material is sublimated when the component reaches a pre-selected temperature, acting as an indicator of the temperatures of the components. The foregoing has more or less broadly outlined the features and technical advantages of the present invention, so that the detailed description that follows can be better understood. The additional features and advantages of the invention which constitute the subject of the claims of the invention will be described hereinafter. It should be appreciated by those skilled in the art that the specific design and modalities set forth herein can easily be used as a basis for modifying or designing other structures in order to carry out the same purposes of the present invention. It should also be recognized by those skilled in the art that such equivalent constructions do not deviate from the spirit and scope of the invention as set forth in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated and form part of the specification, illustrate the embodiments of the present invention and, together with the description, serve to better explain the principles of the invention. In the drawings: Figure IA is a perspective view of an assembly of electrical contacts in combination containing a wear indicator incorporating the invention and a temperature indicator embodying the invention; Figure IB is a partial section, taken along line A-A of Figure IA, showing the construction and assembly of the wear indicator in greater detail; Figure IA is a plan view of a sacrificial contact containing a wear indicator embodying the invention; Figure 2B is a partial section, taken along line C-C of Figure 2A, showing the construction and assembly of the wear indicator in greater detail; Figure 3A is a side view of a sacrificial contact assembly of a transfer computer containing a wear indicator embodying the invention; Figure 3B is a side view of a portion of the sacrificial contact assembly of a transfer switch shown in Figure 3A, showing the emission of a vestigial material immediately after contact wear; Figure 4A is a front view of an electrical contact containing a temperature indicator embodying the invention; Figure 4B is a side view of an electrical contact of Figure 4A; and Figure 4C is a partial section, taken along line B-B of Figure 4A, showing the construction and assembly of the temperature indicator in greater detail. It should be noted that the drawings illustrate only typical embodiments of the invention and should therefore not be considered limiting of its scope, as the invention will admit other equally effective modalities.

DETAILED DESCRIPTION OF THE INVENTION Similar numbers refer to similar parts in all respects. A combination contact assembly 10 having a base 11 made preferably of copper is shown in Figures IA and IB, although any electrically conductive material can be used. The contact assembly in combination 10 is used in the selector switch such as a winding tap selector or a load tap changer, used with a transformer. One or more contact assemblies in combination 10 are provided for each branch of a secondary winding. A second part of the selector switch, not shown in these figures, is used to make contact with the contact assemblies in combination 10, depending on the voltage required by the user. The selector switch, of which the contact assembly in combination 10 is a part, switches between the branches under load, causing arcing and wear. In addition, once the contact assembly in combination 10 is spliced with the second part of the switch, it continues to carry electrical current, making it susceptible to overheating. The base 11 may be provided with one or more holes 12 for mounting the selector switch. One or more sacrificial contact tips 13 are joined and in electrical communication with the base 11. In a preferred embodiment, the sacrificial contact tips 13 are soldered to the base 11. The starting point of the electrical contact between the assembly of contacts in combination and the second part of the selector switch are the sacrificial contact tips 13. After the electric circuit is completed, the electrical contact point changes from the sacrificial contact tips 13 and is then maintained in the base 11. The sacrificial contact tips 13 may be of different material from that of the base 11, since the sacrificial contact tips 13 are subject to the arc formation as the electric circuit is created and interrupted. A preferred embodiment of the invention is to form sacrificial contact tips 13 of a tungsten-based material specifically designed to withstand wear due to arc formation. Base 11 is not subject to arcing or wear, but may fail due to overheating. The sacrificial contact tip 13 is provided with one or more cavities 14. The cavities 14 are formed in the sacrificial contact tip 13, in such a way that the cavities 14 are sealed by joining the slaughter contact tips 13 to the base 11. To allow ease of fabrication, the cavity 14 is preferably cylindrical as a result of drilling, although a cavity 14 of any configuration can be used. The cavity 14 contains a lower part 16 which may be flat, tapered or conical, depending on the method used to form the cavity 14 in the sacrificial contact tip 13. After the cavity 14 has been provided, a vestigial element is inserted. 18 to the cavity 14 and the sacrificial contact tip 13 is inserted to the base 11. Since the contact assembly in combination 10 is used, the slaughter contact tips 13 are worn out by arcing. When the sacrificial contact tips 13 are worn to a sufficient degree, the cavity 14 is opened. Referring now to FIG. IB, a slaughter contact tip 13 is shown as a separate cut along the AA line of FIG. the figure A partial representation of the base 11 is shown. The sacrificial contact tip 13 has a front edge 15, which is preferably beveled. The front edge 15 is the first part of the sacrificial contact tip 13 that touches the second part of the selector switch when the switch is closed and the last part of the sacrificial contact tip 13 that separates to the opposite contact when it is opened the switch. As such, the front edge 15 is the surface of the sacrificial contact tip 13 that is more subject to wear by arc formation. The slaughter contact tip 13 is designed to have a critical point 19. The critical point 19 is the point at which the slaughter contact tip 13 can no longer be used, due to the degree of wear that has occurred. As a slaughter contact tip 13 nears the end of its useful life, the distance between the lower part 16 and the leading edge 15 decreases. As the slaughter contact tip 13 reaches the end of its useful life and the leading edge 15 wears to the critical point 19, the lower part 16 wears out and the cavity 14 opens. The selector switch, the load biasing changer or the turn bias selector in which the contact assembly is used in combination 10 the container or receptacle, not shown in these figures, can be installed in some way. The contacts in the air environment are typically installed in a receptacle for safety reasons and can be inspected visually for wear if the receptacle is opened. The contacts in inert gas environment must be installed in some form of sealed receptacle to contain the inert gas. These receptacles can be opened if the user wishes to fill them with a supply filled with inert gas. The gas may be pressurized at a pressure higher or lower than that of the atmosphere, if the receptacle is properly designed. The contacts that are operated in a vacuum can be installed in a sealed receptacle to preserve the vacuum. Oil operated contacts do not have to be in a sealed environment, but the receptacle must be of sufficient design to stop an amount of oil. As the cavity 14 opens, the vestigial element 18 enters into communication and disperses into the environment surrounding the contact assembly in combination 10. When the presence of the vestigial element 18 is detected by the appropriate detection means with the equipment in which the contact assembly is operated in combination. , the replacement of either the sacrificial contact tip 13 or the contact assembly in combination 10 is indicated. The vestigial element 18 is preferably composed of magnesium sulfate. The detection of the dispersion of the vestigial element 18 within the oil, air, inert gas or vacuum surrounding the contact assembly in combination can be carried out using the existing techniques of spectrophotometric chromatography or using electrochemical transducers. These means for detecting the vestigial element 18 can be remotely employed, similarly to the AGD test, in which the contents of the receptacle surrounding the contact assembly in combination 10 are periodically sampled and tested by any of the preceding or other equivalent techniques for the presence of the vestigial element 18. Alternatively, electrochemical transducers could be mounted within the receptacle, in substantially continuous contact with the contents of the receptacle, allowing an injector located either remotely or locally, operatively connected to the transducers, signal the detection of the presence of the vestigial element 18. After an electrical circuit is completed by the sacrificial contact tip 13, the circuit can be maintained by moving the base 11 to a position in which the current is directed so that it flows through it instead of through the sacrificial contact icio. In such an arrangement, the base 11 is subjected to overheating. According to the above, the base 11 of a combination contact assembly 10 may be provided with one or more concavities. To allow ease of fabrication, the concavity is preferably cylindrical as a result of drilling, although a concavity of any configuration can be used. A preferred embodiment of the invention is to provide a primary concavity 22 and a secondary concavity 23. Contained by the primary concavity 22 and the secondary concavity 23 are the indicator materials 24 capable of detection in a similar manner or equivalent to the detection of the vestigial element. The indicator material 24 can also be placed in a separate container to be riveted or otherwise attached to the base 11. The indicator material 24 is preferably ceramic base and is formulated or selected in such a way that substantially all the amount contained in the concavities 22 and 23 is transformed from a solid phase to the liquid phase at a preselected temperature to be detected. Once in the liquid phase, the indicator material 24 will diffuse to the immediately surrounding environment. When the presence of the indicator material 24 is detected by the appropriate detection means with the environment in which the contact assembly in combination 10 is operated, the replacement or cutting of the contact assembly in combination is indicated 10. In accordance with one embodiment of the invention, the primary concavity 22 of an indicator material 24 having a melting point of 93.3 ° C is filled and secondary concavity 23 of an indicator material 24 having a melting point of 176.6 ° C is reached. . The detection of the presence of the indicator material 24 coming from the primary concavity 22 would thus indicate that the base 11 of the contact assembly in combination 10 has reached the preselected temperature of 93.3 ° C. in operation. The subsequent or synchronous detection of the indicator material 24 from the secondary concavity 23 would indicate that the base 11 of the contact assembly in combination 10 has also reached the preselected temperature of 176.6 ° C in the operation. You could select additional and alternative temperatures, during the selection of different indicator materials 24 with higher or lower melting points. More or fewer concavities 21 could also be provided, or the base 11 of the contact assembly in combination 10 could include pairs of primary concavities 22 and secondary concavities 23. The indicator materials can also be placed in the containers which are then joined to the base 11. Turning now to Figures 2A and 2B, another embodiment of a sacrifice contact is shown. The sacrificial contact 60 is used in a high-voltage switch to open and close electrical circuits, and accordingly is subject to the formation of arcs and wear. The sacrificial contact 60 is provided with one or more cavities 61. To allow ease of fabrication, the cavity 60 is preferably cylindrical as a result of drilling, although a cavity 61 of any configuration can be used. The cavity 61 contains a lower portion 62 which may be flat, tapered or conical, depending on the method used to form the cavity 61 in the sacrificial contact 60. After the cavity 61 is provided, the vestigial element 18 is inserted into the cavity 61. cavity 61 and the cavity 61 is closed with a plug 63. As we use a sacrificial contact 60 to create and cut electrical circuits, wear occurs. When the sacrificial contact 60 wears to a sufficient degree, the cavity 61 opens. Referring now to Figure 2B, the slaughter contact 60 is shown as a separate cut along the line C-C of Figure 2A. The sacrificial contact 60 is designed to have a critical point 64. According to the sacrificial contact 60 the end of its useful life approaches, the distance between the lower part 62 and the surrounding material decreases. As in sacrificial contactor 60 reaches the end of its useful life, worn to the critical point 64, the lower part 62 is worn and the cavity 61 is opened. Turning now to figures 3A and 3B, it is shown as a contact assembly of sacrifice 30 another mode of a slaughter contact, used as a transfer switch. The sacrificial contact assembly 30 has a base 31 which may be made of copper, bronze or any other electrically conductive material. One or more sacrificial contact tips 33 are attached to the base 31. The sacrificial contact tip 33 is provided with one or more cavities 34. The cavities 34 are formed in a sacrificial contact tip 33 in such a way that they seal the cavities 34 when the sacrificial contact tips 33 are attached to the base 31. The cavity 34 is preferably cylindrical as a result of a drilling, although a cavity 34 of any configuration can be used. The cavity 34 contains a lower part 36, which may be flat or used, depending on the method used to form the cavity 34 in the sacrificial contact point 33. After providing cavity 34, a vestigial element 18 is inserted into the cavity 34. and sacrificial contact tip 33 is attached to the base 31. The slaughter contact source 33 is also provided with a front edge 35 and a critical point 39. As slaughter contact assembly is used To open and close the electric circuits, the sacrificial contact tips 33 wear out due to the formation of electric arcs. When the sacrificial contact tips 33 are worn to a sufficient degree, the cavity 34 is opened. Referring now to Figure 3B, a partial representation of a sacrificial contact assembly 30 is shown. The front edge 35 of the tip of sacrificial contact 33 has been worn more or less from the critical point 39, the lower part 36 worn out and opening the cavity 34. As a result, the vestigial element 18 has been dispersed to the environment surrounding the sacrificial contact assembly 30. Referring now to Figures 4A to 4C, contact 50 is shown. Contact 50 is suitable for use in an inversion switch. An inversion switch is part of a high-voltage switch that conducts charge continuously during operation and is therefore subject to heating and not to arcing and wear. Although not represented in these figures, in the operation, the sacrificial contact assembly 30 or sacrificial contact 60 is operatively and electrically connected to a contact element such as a contact 50 by well-known means. The contact 50 is provided with one or more concavities. To allow ease of fabrication, the concavity is preferably cylindrical as a result of drilling, although a concavity of any configuration can be used. A preferred embodiment of the invention is to provide a primary concavity 52 and a secondary concavity 53. Contained by the primary concavity 52 and the secondary concavity 53 are the indicator materials 54 capable of detection in a manner similar or equivalent to the detection of the vestigial element. as discussed previously, since the contact 50 is used in an environment of oil, inert gas, air, or vacuum as used for the contact assembly in combination 10. The indicator material can also be placed 54 in a separate vessel to be joined with rivets or otherwise to contact 50. Indicator material 54 is preferably ceramic based and is formulated or selected in such a way that substantially the entire amount, when the respective concavities 52 and 53, will be transformed from a solid phase to the liquid phase at a selected temperature to be detected. The contact 50 is therefore preferably contained in oil, to allow easy diffusion of the indicator material 54 from the contact 50. Once in the liquid phase, the indicator material 54 will diffuse into the immediately surrounding oil environment. Other operating environments may be used, depending on the selection of the indicator material 54 and the appropriate detection means. When the presence of the indicator material 54 is detected by the appropriate detection means with the environment in which the contact 50 is operated, replacement or cutting of the commutator within which the contact 50 operates is indicated. According to an embodiment of the invention, the secondary concavity 52 of an indicator material 54 having a melting point of 93.3 ° C is filled and the secondary concavities 53 are filled with an indicator material 56 having a melting point of 176.6 ° C. The detection of the presence of indicator material 54 coming from the primary concavity 52 would thus indicate that contact 50 has reached the preselected temperature of 93.3 ° C in the operation. Subsequent or synchronous detection of indicator material 54 from secondary concavity 53 would indicate that contact 50 has also reached the preselected temperature of 166.6 ° C of the operation. Additional and alternative temperatures could be preselected if desired, by selecting different indicator materials 54 with higher or lower melting points. It could also provide more or less concavities. Indicator materials can also be placed in the containers that are attached to the contact 50. Turning now to Figure 4C, the contact 50 is shown as a separate cut along the line B-B of Figure 4A. The primary concavity 53 which is filled with material 54 is shown.

It will be apparent that the wear and temperature detection means described with reference to the figures described above could be used in the combination contact assembly 10 or in the combination of the sacrificial contact assembly 30 or the sacrificial contact 60 electrically connected to the contact 50. Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations may be made herein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (18)

NOVELTY OF THE INVENTION CLAIMS

1. - An electrical contact assembly configured for operation in an oil environment, comprising: a conductive base; at least one sacrificial contact tip mounted and operatively connected to the base; and means for indicating when said at least one slaughter contact tip has been worn, to a predetermined point of wear.

2. - The electrical contact assembly according to claim 1, further characterized in that said at least one sacrificial contact tip defines at least one cavity and further comprises a vestigial element contained within said at least one cavity.

3. - The electrical contact assembly according to claim 2, further characterized in that said means for indicating when said at least one slaughter contact tip has been worn, at said predetermined wear point, comprises defining the formation of a opening in said at least one opening cavity through which said vestigial element can be dispersed.

4. - The electrical contact assembly according to claim 2 or 3, further characterized in that said vestigial element comprises magnesium sulfate.

5. - The electrical contact assembly according to claim 1, further characterized in that the at least one slaughter contact tip comprises a material resistant to wear by arcing.

6. - The electrical contact assembly according to claim 1, further characterized in that the at least one sacrificial contact tip comprises a wear-resistant tungsten-based material by arcing.

7. A sacrificial contact assembly configured for operation within an oil environment, comprising: at least one sacrificial contact point attached to said base; and means for indicating when said at least one sacrificial contact tip has worn to a predetermined wear point.

8. - The electrical contact assembly according to claim 7, further characterized in that said at least one sacrificial contact tip defines at least one cavity and further comprises a vestigial element contained within said at least one cavity.

9. - The electrical contact assembly according to claim 8, further characterized in that said means for indicating when said at least one sacrificial contact tip has been worn, at said predetermined wear point, comprises defining the formation of a opening in said at least one opening cavity through which said vestigial element can be dispersed.

10. The electrical contact assembly according to claim 8 or 9, further characterized in that said vestigial element comprises magnesium sulfate.

11. The electrical contact assembly according to claim 7, further characterized in that the at least one sacrificial contact tip comprises a wear-resistant tungsten-based material by arcing.

12. - The electrical contact assembly according to claim 7, further characterized in that the at least one slaughter contact tip comprises a material resistant to wear by arcing.

13. - A method for determining when maintenance requires an electrical contact assembly that operates within an oil environment and that has at least one slaughter contact tip mounted to a conductive base, the method comprising: defining a cavity within of the at least one sacrificial contact tip; provide a vestigial element within said at least one cavity; causing said at least one sacrificial contact to wear out until an opening is formed in said at least one sacrificial contact; allowing said vestigial element to be dispersed in said cavity through said opening to said oil environment; and monitoring said oil environment to determine when a sufficient amount of trace element has been dispersed to said oil environment to indicate that said electrical contact assembly requires maintenance.

14. - The method of compliance with the claim 13, further characterized in that the monitoring step also comprises using dissolved gas analysis (AGD) to identify when a sufficient amount of trace element has been dispersed to said oil environment to indicate that said electrical contact assembly requires maintenance.

15. The method according to claim 13, further characterized in that the step of monitoring comprises also using infrared monitoring to identify when a sufficient amount of trace element has been dispersed to said oil environment to indicate that said electrical contact assembly maintenance required.

16. The method according to the claim 13, further characterized in that said vestigial element comprises magnesium sulfate.

17.- The method according to the claim 13, further characterized in that the at least one slaughter contact tip comprises a wear resistant material by arcing.

18. - The method according to claim 13, further characterized in that the at least one sacrificial contact tip comprises a wear-resistant tungsten-based material by arcing.