MXPA97007043A - Electrical device, such as a network protector relay, with circuit board stamp print - Google Patents

Abstract

The present invention relates to a network protective unit, comprising: a housing having an opening, a relay mounted within said housing and having relay terminals extending therefrom, external terminals outside said housing; printed circuit having air-tight and water-tight electrical connections connecting said relay terminals to said external terminals, means securing said printed circuit board through said opening to form an air and water tight seal for said housing; said printed circuit board comprises an insulating substrate, and said air-tight and water-tight electrical connections comprise tinned openings therethrough extending through said substrate and into which said relay terminals are inserted from within said housing and said external terminals are inserted from outside said housing and in which said Relay terminals and external terminals are secured by welding, where said openings include first tinned openings therethrough into which said relay terminals are inserted from within said housing and secured with solder, and second tinned openings therethrough in which insert said external terminals from outside said housing and secure them with welding, and where said air and water tight connections also include associated conductive traces in said substrate that electrically connect corresponding openings of said tinned openings through it first and second; said printed circuit card has encapsulation material applied on at least some connections on an external side of said substrate external to said housing, and wherein said printed circuit card has an encapsulation containment which confines said encapsulation material applied to said outer side of said sutra

Description

ELECTRICAL DEVICE. SUCH AS A PROTECTIVE RELAY OF NETWORK. WITH PRINTED CIRCUIT BOARD SEAL Background of the Invention Field of the Invention The present invention relates to electrical devices that are protected from ambient conditions by sealing them in an air-tight housing and to the water through which the electrical conductors for the device must extend. It has particular application in protective relays for network protectors and uses a printed circuit board, through which external electrical connections to the device are made, which serve as a cover for the housing. Related Information In many installations, it is necessary to protect an electrical device from environmental conditions while providing the device with external connections to another device. One of these installations is the relay for a network protector. The network protector is the device used to control the flow of electrical energy to a distribution network such as a section of a city, a large building or an industrial zone. This network is fed at multiple points through transformers. The network protector includes a circuit breaker and a relay that opens the circuit to the transformer when an abnormal current flow is detected. Typically, the transformer is mounted in a vault, often underground. As the vault may contain water and the transformer may overheat or even catch fire, the circuit breaker and its protective relay are mounted in a sealed tank. However, to further protect the relay, it is mounted in a sealed housing inside the tank. The protective relay requires numerous electrical connections such as the current transformers that detect the mains currents and the circuit breaker. The conduits in which the insulated relay cables are held by a rubber gasket in the penetration through the housing have proven to be unsatisfactory, even if the gasket is hermetically sealed around the conductors, since air and moisture can pass between the conductor and the insulation and along the individual wires of the tornadoed conductors. Currently, the practice is to use feed-throughs in which glass plugs are fused with short sections of cable into openings in a metal plate. The relay cables are soldered to circuits at the internal ends of the passages, while the corresponding external conductors are soldered to circuits at the external ends. These interns are expensive. There is therefore a need for improved arrangements for making electrical connections to electrical devices enclosed in a housing, and in particular to network protective relays. There is a need to provide improved provisions that are economical and easy to implement. In addition there is the requirement of hermetic provisions to air and water. SUMMARY OF THE INVENTION These and other needs are overcome by the invention which is directed to an apparatus for protecting electrical devices from ambient conditions while providing electrical connections to the device. The apparatus includes a housing having an opening and in which the electrical device is mounted. A printed circuit board comprising an insulating substrate and electrical connections to connect the conductors of the device to the corresponding external connectors. Electrical connections are included through openings extending through the substrate into which the conductors of the device are inserted from within the housing and the external conductors are inserted from outside the housing. The conductors are secured in the tinplate through the openings by welding. The apparatus further includes means securing the printed circuit board over the housing opening to form an air and water tight seal. Preferably the openings of the substrate include first openings in which the conductors of the device are secured by welding and second openings in which the outer conductors are secured by welding. Conductive traces on the substrate electrically connect the first and second openings for the corresponding device conductors and external ones. Preferably, the printed circuit board has an electrically insulating material applied on at least the solder connections on the outer side of the printed circuit board. More preferably, the insulating material is an encapsulation material that is contained within encapsulation regions surrounding the portions of the printed circuit board to be encapsulated. In another aspect of the invention, the components can be mounted on each side of the printed circuit board. In addition, components such as connectors for external wiring and indicators such as, for example, light emitting diodes (LEDs) can be supported in the encapsulation enclosure. The invention has particular application to network protective relays. The components mounted on the printed circuit board that form the seal for the housing may include, for example, auxiliary current transformers, and load resistors that convert the detected currents into voltages for input to the relay. These components can be on either side of the printed circuit board, but preferably the load resistors are inside and the auxiliary current transformers are on the outside. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood on the basis of the following description of the preferred embodiments taken in conjunction with the accompanying drawings, in which: Figure 1 is a schematic view of a network transformer having a network protector that includes a network protective relay incorporating the invention. Figure 2 is a longitudinal section through a network protective relay and its housing according to the invention. Figure 3 is an isometric view of a printed circuit board forming part of the enclosure of the relay illustrated with parts in section. 4A-4C are fragmentary cross-sectional views through portions of the printed circuit board illustrating conductor connections according to three embodiments of the invention. Figures 5A-5C are plan views of the connections of Figures 4A-4C. Description of the Preferred Embodiment The invention will be described as applied to the protection of a network protective relay with which it has particular application. However, it will be noted that the invention can also be applied to protect other types of electrical devices from ambient conditions while providing connections between the device and external wiring that are air and water tight. Figure 1 illustrates a network protector 1 used in conjunction with a transformer 3 that feeds a network 5, which, for example, can power a part of a city, a large building, an industrial plant or other local electrical distribution systems. The network 5 is powered by a number of other transformers (not shown) similar to the transformer 3. Often, the transformer 3 with its network protector 1 is installed in an underground vault 7 in which water can accumulate. In this way, the network protector 1 is housed in a water-tight and air-tight tank 9. The network protector 1 includes a circuit breaker 11 and a relay unit 13. A main function of the relay unit 13 is to detect the flow of abnormal current through the transformer which may include current flow outside the network 5 through the transformer 3 in the case of certain fault conditions. The relay unit 13 includes a protective relay 15 and an enclosure 17 for the relay as can be seen in figure 2. The enclosure 17 includes a housing 19 having an opening 21 at one end which, as will be seen, is closed by an enclosure in the form of a printed circuit board (PCB) 23. The protective relay 15 in the preferred embodiment is a digital relay which, for example, includes a power PCB 25 and a processor PCB 27 which are supported in spaced relationship at one end by a mounting spacer 29 secured to the PCB23 which serves as the main board, and at the other end by a locating support with notch 31 secured to the housing 19. The electrical connections between the power PCB 25 and the processor PCB 27 are made by inter-board connectors 33. A spacer 35 maintains a fixed spacing between the boards at the ends supported by the PCB locator 31. The printed circuit board 23 serves as a cover for the opening 21 in the housing. The board 23 is secured over the opening 21 by screws 37 which extend through the PCB 23 and are sealed with seal rings 39. The screws 37 are threaded into mounting protrusions 41 fastened to the interior of the housing 19. A gasket 43 is fastened between the printed circuit board 23 and the housing 19 to provide a watertight and air tight seal. The printed circuit board 23 also provides connections 45 between the relay conductors 47 and the external conductors 49. As can be seen more clearly in FIGS. 3 and 4A-C and 5A-C, the electrical connections 45 include tinning through the openings 51 in the printed circuit board 23. In the preferred embodiment of the invention, stripped ends 47w of the relay conductors 47 are inserted into first openings 51a from the inner side 23a of the printed circuit board and secured in place by welding 53. Similarly, the stripped end 49w of the corresponding external conductor 49 is inserted from the outer side 23b of the printed circuit board into a corresponding second tinned opening 57b laterally spaced from the opening 51a and is also filled with weld 53. The weld 53 is introduced into the openings 51a from the outer side 23b of the printed circuit board 23, while additional welding 53 is introduced and n the openings 51b from the inner side 23a of the printed circuit board where there is no interference from the conductor being connected. In this way, a solid weld connection can be made easily airtight to air and water. The corresponding weld-filled openings 51a and 51b are electrically connected by an electrically associated conductive trace 55 on the PCB 23. These connected traces can be made on one or both sides of the printed circuit board 23. Although the conductive traces 55 are on the inner side 23a of printed circuit board 23, there are electrical connections exposed on outer side 23b. to electrically isolate these connections, an encapsulation material 57 can be applied to the outer side 23b of the printed circuit board 23. Preferably, as can be seen in Figures 2 and 3, an encapsulation containment 59 surrounds the section of the printed circuit board 23 which is going to be encapsulated. For example, an aluminum angle piece may have a flange 59f cut at the corners and bent to form an enclosure. The cut tabs are secured to the printed circuit board such as, for example, by the mounting screws 37. The encapsulation containment 59 not only encloses the encapsulation material 57, but can also serve as a mount for various types of components. For example, connectors such as the communications connector 61 can be mechanically mounted in an opening 63 in the rising flange 65 of the encapsulation containment 59. The external connectors 49c connected to these connectors 61 are bent at right angles to penetrate the PCB23 to through a connection 45 as described above. Another example of a component that can be supported by the encapsulation containment 59 is the light emitting diode (LED) 67 which is mounted in an opening 69 in the rising flange 65 of the encapsulation containment 59. Again, the external conductors 471 for the LEDs are bent at right angles and are connected to the printed circuit board 23 by a connection 45. Yet another example of a component mounted on the printed circuit board 23 that forms the enclosure for the housing 19 is a current transformer. auxiliary (CT) 71. As illustrated in figure 3, these auxiliary CRs 71 are mounted on a platform 73 having four pins 49p (l), 49p (2), and 49s (l) and 49s (2), which form electrical connections for the primary and secondary windings of the CT as well as mechanically support the CT 71 on the printed circuit board 23. The pins 49p (l) and 49p (2) for the primary winding of the CT formed by the cable 49p are inserted into third tinned through openings 51p from the outer side 23b of the board of printed circuit 23 as illustrated in FIGS. 4C and 5C. Since the primary windings 49p of the CT are connected to main CTs (not shown) external to the enclosure 17, the corresponding conductors 49q connected to the main CTs also penetrate four openings 53q of the outer side 23b of the PCB 23. The corresponding openings 51p and 51q are connected on the inner side 23a of the PCB 23 by the associated conductive traces 55p to complete the connections 45 '. Other components, typically mounted on the platform, can be mounted on the printed circuit board 23 in a similar manner on the inner side 23a or on the outer side 23b. Another example of a component that can be mounted on the PCB 23 is a load resistor 75 for converting the currents detected by the Cts into voltages to enter the relay. In this case, each connection 45"for the ends of the load resistor 75 includes, as illustrated in FIGS. 4B and 5B, three openings: a first opening 51a in which the conductor to the relay is welded, an opening 51b to which a spigot 49s (1) for the secondary coil of the CT 71 is welded, and an additional opening 51r in which a lead 77 from the load resistor 75 is welded by welding 53. These three openings are then connected by a common conductive trace associated 66s. A similar connection is made at the other end of the load resistor, the secondary winding of the CT and the relay conductor so that the load resistor 75 is connected through the secondary winding of the auxiliary CT 71. Described in specific embodiments of the invention, those skilled in the art will appreciate that various modifications and alternatives may be made based on the foregoing description. uencia, the particular provisions disclosed are only illustrative and do not limit the scope of the invention which is fully included in the appended claims and any equivalent thereof.

Claims (17)

1. A network protective unit, comprising: a housing having an opening; a relay mounted within said housing and having relay conductors extending therefrom; external drivers outside said housing; a printed circuit board having air-tight and water-tight electrical connections connecting said relay connectors to said external conductors; and means securing said printed circuit board through said opening to form an air and water tight seal for said housing. A network protective relay unit according to claim 1, wherein said means securing said printed circuit board through said opening includes a seal gasket and fastening means holding said seal gasket between said gas panel. printed circuit and said housing around said opening. 3. A network protective relay unit according to claim 1, wherein said printed circuit board comprises an insulating substrate, and said air-tight and water-tight electrical connections comprise conductive traces on said sub-trace for corresponding traces of said conductors. relay and said external conductors, first solder connections between each of said relay conductors and an associated conductive trace, and second solder connections between each of said external conductors and a conductive trace associated with a corresponding relay conductor. A network protective relay unit according to claim 3, wherein said first welding connections comprise first openings extending through said substrate in which said relay conductors are inserted and which are filled with welding, and said second welding connections comprise second openings extending through said substrate in which said external conductors are inserted and which are filled with welding, said associated conducting traces extending between said first and second openings and in electrical contact with said welding. 5. A network protective relay unit according to claim 4, wherein said first and second openings are tinned through the openings. A network protective relay unit according to claim 1, wherein said printed circuit board comprises an insulating substrate, and said air-tight and water-tight electrical connections comprise tinned through openings extending through said substrate and in which said relay conductors are inserted from inside said housing and said external conductors are inserted from said exterior of said housing and where said relay conductors and external conductors are secured by welding. A network protective relay unit according to claim 6, wherein said openings include first openings in which said relay conductors are inserted from inside said housing and secured with solder and second tinned through openings in which said external conductors are inserted from the outside of said housing and secured with welding, and wherein said air and water tight connections further include associated conductive traces on said substrate electrically connecting the corresponding openings of said first and second tinned through openings. A network protective relay unit according to claim 7, wherein said printed circuit board has components mounted thereon by conductors inserted into additional tinned through openings and secured therein by welding, said tinned through openings being connected electrically by a conductive trace with the selected openings of said first and second openings. 9. A network protective relay unit according to claim 7, wherein said printed circuit board has encapsulation material applied on at least some connections on an external side of said substrate external to said housing. A network protective relay unit according to claim 9, wherein said printed circuit board has an encapsulation containment enclosing said encapsulation material applied to said outer side of said substrate. A network protective relay unit according to claim 10, including components supported in said encapsulation containment, connected to said external conductors and wherein said encapsulation material electrically isolates said external conductors connected to said components. A network protective relay unit according to claim 7, wherein said printed circuit board has components mounted on a first side thereof and wherein said air and water tight connections include third tinned through openings extending to Through said substrate in which conductors of the components are inserted from said first side of said printed circuit board and secured with solder, fourth tinned through openings extending through said substrate in which conductors are inserted also from said first side of said printed circuit board and secured with soldering, and additional associated conductive traces on said substrate electrically connecting to the corresponding openings of said third and fourth tinned through openings. 13. An apparatus for protecting from environmental conditions an electrical device having device leads to be connected to external conductors, said apparatus comprising: a housing having an opening and in which said electrical device is mounted; a printed circuit board having a substrate and electrical connections for connecting said device conductors to corresponding ones of said external conductors, said electrical connections including openings extending through said substrate in which said conductors of the device are inserted from the inside of said housing and said external conductors are inserted from outside said housing and in which said device conductors and external conductors are secured by welding; and means securing said printed circuit board over said opening to form an air and water tight seal for said housing. An apparatus according to claim 13, wherein said openings in said substrate comprise first tinned through openings in which the conductors of the device are secured by said welding and second tinned through openings in which said external conductors are secured by said welding , and conductive traces on said substrate that electrically connect said first openings with said second openings for the corresponding conductors of the device and external. 15. An apparatus according to claim 13, wherein said printed circuit board further has electrically insulating material applied on said solder on an outer side of said printed circuit board. 16. An apparatus according to claim 14, including containment means for confining said insulating material electrically on said outer side of said printed circuit board. 17. An apparatus according to claim 15, including components supported by said containment means and connected to said external conductors that are electrically isolated by said electrically insulating material.