A device for remote monitoring and indication of TMOV

Abstract

A device for remote monitoring and indication of a TMOV is disclosed. The TMOV features one or more magnets connected to an arc barrier and a sensor of the TMOV. Upon a fault condition, the arc barrier moves to place the magnet near the sensor, causing the sensor to indicate the fault condition, allowing a technician to repair or replace the TMOV.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to metal oxide varistors (MOVs), and more particularly, to surge protection devices including MOVs. Background Art

[0002] Surge protection devices (SPDs) are used to protect electronic circuits and components from damage due to overvoltage fault conditions. Some SPDs may include a metal oxide varistor (MOV) connected between the protected circuit and ground. MOVs have specific current-voltage characteristics that allow them to be used to protect such circuits from catastrophic voltage surges. Some SPDs utilize spring elements soldered to the electrodes of the MOV. When an abnormal condition occurs, the solder melts and the spring moves, resulting in an open circuit. In particular, when the voltage is greater than the rated voltage or threshold voltage applied to the device, current flows through the MOV, generating heat. This causes the link element to melt. Once the link melts, an open circuit is formed, which prevents the MOV from catching fire.

[0003] One type of SPD, a thermally protected metal oxide varistor (TMOV), does not have a remote monitoring status indication to show whether its thermal fuse is open during normal operation. This lack of status indication makes it unclear whether the TMOV is functioning. As a result, replacement of an inoperative TMOV may be delayed, putting the equipment protected by the TMOV surge at risk.

[0004] For these and other considerations, the present improvement may be useful. Summary of the invention

[0005] This summary is provided to introduce a selection of some concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended as an aid in determining the scope of the claimed subject matter.

[0006] An exemplary embodiment of a surge protection device according to the present disclosure may include: a metal oxide varistor (MOV) having an electrode; a spring adjacent to the MOV and having a contact pin connected to the electrode by solder paste; an arc barrier adjacent to the spring, the arc barrier sliding over the electrode in response to the solder paste melting; a magnet on the arc barrier moving synchronously with the arc barrier; and a sensor providing an indication, the magnet approaching the sensor once the arc barrier slides over the electrode.

[0007] An exemplary embodiment of a thermally protected metal oxide varistor (TMOV) status system according to the present disclosure may include a TMOV and a reporting circuit. A sensor is located within a housing of the TMOV, and a magnet is located on an arc barrier of the TMOV. The magnet moves in coordination with the arc barrier. Once the magnet approaches the sensor, the sensor provides an indication. The reporting circuit sends a signal in response to receiving the indication.

[0008] An exemplary embodiment of a thermally protected metal oxide varistor (TMOV) according to the present disclosure may include a metal oxide varistor (MOV) having an electrode, a spring adjacent to the MOV, an arc barrier adjacent to the spring, a magnet located on the arc barrier, and a reed switch. The spring has a contact pin connected to the electrode using solder paste. The arc barrier includes a tensioning spring that slides the arc barrier over the electrode once the solder paste melts. The magnet moves simultaneously with the arc barrier. The reed switch has two blades, and when the arc barrier is above the electrode, the magnet is close to the reed switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is a diagram showing a thermal protection type metal oxide varistor according to the prior art;

[0010] Figures 2A-2D is a diagram showing a thermal protection type metal oxide varistor according to an exemplary embodiment; and

[0011] Figure 3 is a diagram illustrating a state system of a thermally protected metal oxide varistor according to an exemplary embodiment. DETAILED DESCRIPTION

[0012] A novel thermally protected metal oxide varistor (TMOV) and TMOV status system are disclosed. The TMOV has a sensor and one or more magnets. The one or more magnets are connected to an arc barrier. Upon a fault condition, the arc barrier slides to protect the MOV, causing the one or more magnets to approach the sensor, thereby providing an indication. When the sensor is a reed switch, the indication is the closure of the switch. The TMOV status system includes a reporting circuit for receiving the indication from the sensor and issuing a signal, which may be visual or audible, to enable a technician to repair or replace the TMOV after a fault event.

[0013] Figure 11 is a representative view of a surge protection device (SPD) known as a thermally protected metal oxide varistor (TMOV) 100 according to the prior art. TMOV 100 includes housing 102, spring 104, arc barrier 106, MOV 108, first pin 110, and second pin 112. MOV 108 (which may be epoxy coated) includes electrode 114, which is circular in this example. Spring 104 and second pin 112 may alternatively be formed as a single conductive piece and include contact pin 116. Contact pin 116 of spring 104 is welded to electrode 114 of MOV 108.

[0014] During the assembly process, solder paste is placed between the contact pin 116 and the electrode 114 of the MOV 108. After reflow, the solder paste becomes solid, thereby forming an electrical connection between the spring 104 and the electrode 114 of the MOV 108. When a fault condition occurs, the solder melts due to the overheating caused by the fault condition, thereby breaking the connection between the spring 104 and the electrode 114.

[0015] exist Figure 1 , the TMOV 100 is not "tripped". Therefore, the arc barrier 106 is not directly disposed on or above the electrode 114 of the MOV 108. In the event of a fault, a tension spring (not shown) connected to the arc barrier 106 causes the arc barrier to move over the electrode 114 and ensure reliable electrical insulation. Therefore, the arc barrier 106 is a slider device that protects the MOV 108 from catching fire. In addition, the solder paste connecting the contact pin 116 and the electrode 114 melts, causing the spring 104 to move away from the electrode, resulting in an open circuit. Once the contact pin 116 is no longer attached to the electrode 114, the spring of the arc barrier 106 pushes the arc barrier over the electrode, while the arc barrier pushes the contact pin 116 further away from the electrode. Generally speaking, solder paste is used to electrically connect the contact pin 116 to the electrode 114 of the MOV 108, and the solder paste has a lower melting point relative to the other components of the TMOV 100. Thus, before the arc can ignite the MOV 108 , the solder melts and the arc shield 106 provides covering for the electrode 114 .

[0016] Conventional TMOV devices lack a remote monitor to indicate whether the TMOV has been activated as described above. Once the solder melts, an open circuit results because there is no longer a connection between the electrode 114 of the MOV 108 and the pin 112 of the spring 104. Therefore, the occurrence of a fault event means that the TMOV should be replaced or repaired so that the arc barrier 106 slides back to its original position and the contact pin 116 reattaches to the electrode 114. Without some kind of indication, the circuit protected by the TMOV is at risk.

[0017] Figures 2A-2D is a representative diagram of a novel TMOV 200 that solves the above-mentioned drawbacks according to an exemplary embodiment. Figure 2A This is a top view of TMOV 200. Figure 2B This is a perspective view of TMOV. Figure 2C and 2D 2 is a perspective view of a TMOV housing. TMOV 200 includes housing 202, spring 204, arc barrier 206, MOV 208, first pin 210 and second pin 212. MOV 208 (which may be epoxy coated) includes an electrode 214, which is circular in this example. Spring 204 and second pin 212 may alternatively be formed as a single conductive sheet and include contact pin 216. Contact pin 216 of spring 204 is welded to electrode 214 of MOV 208.

[0018] During the assembly process, solder paste is placed between the contact pin 216 and the electrode 214 of the MOV 208. After reflow, the solder paste becomes solid, thereby forming an electrical connection between the spring 204 and the electrode 214 of the MOV 208. When a fault condition occurs, the solder melts due to the overheating caused by the fault condition, thereby breaking the connection between the spring 204 and the electrode 214.

[0019] In two Figure 2A and 2B The arc barrier 206 is visible in both figures. When a fault event occurs, the tension springs 232 (one of which is shown in FIG. 1 ) connected to either side of the arc barrier 206 are Figure 2B The arc barrier 206 thus protects the MOV 208 from catching fire. In addition, the solder paste connecting the contact pin 216 to the electrode 214 melts, causing the spring 204 to move away from the electrode, resulting in an open circuit. Once the contact pin 216 is no longer attached to the electrode 214 (e.g., Figure 2B As shown), the tension spring 232 pushes the arc shield 206 over the electrode, while the arc shield pushes the contact pin 216 further away ( Figure 2B Generally, the solder paste used to electrically connect the contact pin 216 to the electrode 214 of the MOV 208 has a lower melting point relative to the other components of the TMOV 200. Therefore, the solder melts before the arc can ignite the MOV 208, and the arc shield 206 provides coverage for the electrode 214.

[0020] In two Figure 2A and 2BThe arc barrier 206 is visible in the embodiment. In the exemplary embodiment, the arc barrier 206 is equipped with two magnets 226a and 226b (collectively referred to as "magnets 226"). Magnet 226a is disposed on the arc barrier 206 on one side of the spring 204, and magnet 228b is disposed on the arc barrier on the opposite, second side of the spring. In the exemplary embodiment, once the arc barrier 206 slides over the electrode 214 of the MOV 208 in response to a fault event, the magnet 228 slides with the arc barrier. For example, in Figure 2A In the illustration of FIG. 2 , in the non-fault state of the TMOV 200, the arc barrier 206 is substantially located to the left of the electrode 214, and in the fault state of the TMOV 200, the arc barrier 206 slides to the right to cover the electrode. Due to the deployment of the magnet 228 on the arc barrier 206, the magnet 228 also slides to the right, and thus is closer to the sensor 220 in the fault state of the TMOV 200. In an exemplary embodiment, the proximity of the magnet 228 to the sensor 220 activates the sensor. In an exemplary embodiment, the TMOV 200 is implemented by a single magnet disposed on one side of the arc barrier 206.

[0021] In an exemplary embodiment, sensor 220 is a status indicating device integrated into TMOV 200. In a non-limiting example, sensor 220 is cylindrical and has two opposing ends, each end connected to a wire. One end of the sensor is connected to wire 222a, and a second end of the sensor is connected to wire 222b (collectively referred to as "wire 222") for connecting the sensor to an indicating circuit. In an exemplary embodiment, sensor 220 is located in housing 230 ( Figure 2C ) wherein the housing includes an opening 234 through which the wire 222 passes so as to be external to the TMOV and attachable to an indicating circuit. In another embodiment, the sensor 220 is attached to the housing 230.

[0022] In an exemplary embodiment, sensor 220 is a magnetic sensor known as a reed switch. A reed switch is an electrical switch that is operated by an applied magnetic field. A flexible metal contact at either end of the reed switch housing is connected to an electrical circuit. In the absence of a magnetic field, the reed switch is in an open position. When a magnetic field is present, the metal contacts contact each other, thereby closing the switch. In an exemplary embodiment, the magnetic field that activates sensor 220 is achieved by a magnet 228 attached to arc barrier 206. As a reed switch, when sensor 220 is activated by magnet 228, it closes the circuit to which wire 222 is connected. The circuit is thus conducted.

[0023] In an exemplary embodiment, the housing 202 and the housing 230 are a "snap-on design" where the housing slides into the housing like two parts of a snap. Once the housing 202 is installed in the housing 230, the MOV 208 is disposed between the sensor 220 and the housing 230, as shown in FIG. Figure 2A As shown. Thus, the sensor 220 is disposed near the coating of the MOV 208, and in some embodiments is located on the coating. In another embodiment, the sensor 220 is fixed to the outer cover of the TMOV 200.

[0024] In an exemplary embodiment, despite being close to electrode 214, sensor 220 is not adversely affected by heating of electrode 214 during a fault event. In one embodiment, the epoxy or other coating of MOV 208 isolates sensor 220. In another embodiment, sensor 220 itself is protected by a coating surrounding its body, such as a cylindrical glass tube. Thus, once electrode 214 of MOV 208 heats in response to a fault condition, sensor 220 continues to function.

[0025] exist Figure 2A and 2B In a non-limiting example, magnet 226 is shown as a triangular magnet. In some embodiments, magnet 226 is square or rectangular in shape. In other embodiments, the magnet is circular or cylindrical. In other embodiments, the magnet is irregularly shaped. In an exemplary embodiment, magnet 226 provides a magnetic field that triggers sensor 220 when it is close to sensor 220, thereby closing the circuit to which the sensor is connected.

[0026] In an exemplary embodiment, the sensor 220 is a status indicating device to remotely monitor whether the TMOV 200 is functional. Once the TMOV 200 enters a fault state, the solder attaching the contact pin 216 of the spring 204 to the electrode 214 of the MOV 208 melts, resulting in an open circuit. Therefore, the TMOV 200 in this state no longer functions properly. In other words, once the solder connecting the spring 204 to the MOV 208 melts, the TMOV 200 is thermally disconnected from the circuit and no longer functions. When the TMOV 200 is thermally disconnected from the circuit, the tensioning spring 232 will push the arc barrier 206 to move above the electrode 214 to ensure reliable electrical insulation. A thermally disconnected TMOV cannot provide fault protection for the connected circuit. The sliding operation of the arc barrier 206 caused by the tensioning spring 232 provides electrical insulation for the MOV 208 from arc events. Compared with the prior art TMOV 100 ( Figure 1), two magnets 226 mounted on the sliding arc barrier 206 move closer to the sensor 220 during the sliding operation than when the sensor 220 is in operation. For the reed switch embodiment, when the magnetic field strength is large enough, the blades in the reed switch change from open (not connected) to closed (connected). In an exemplary embodiment, the presence of the magnets 226 near the sensor 220 notifies the reporting circuit. When the sensor 220 is a reed switch, the closure of the switch provides notification that the TMOV 200 is no longer operating. In this way, the functionality of the TMOV 200 can be determined remotely.

[0027] Figure 3 is a representative diagram of a TMOV status system 300 according to an exemplary embodiment. The TMOV status system 300 has Figures 2A-2D The features of TMOV 200 include sensor 220 and magnets 226a and 226b. In an exemplary embodiment, once magnets 226a and 226b are close to the sensor, as described above, reporting circuit 302 receives indication 304 from sensor 220. As an example, indication 304 can be a signal. Wherein when sensor 220 is a reed switch, the closure of the switch provides indication 304 by closing a circuit consisting of the reed switch and indication circuit 302. In response to receiving indication 304, reporting circuit 302 can send signal 306. In one embodiment, reporting circuit 302 is away from TMOV 200.

[0028] In an exemplary embodiment, the wires 222a and 222b of the sensor 220 are connected to the reporting circuit 302 so that the indication 304 can be transmitted to the reporting circuit. Where the sensor 220 is a reed switch, the indication 304 is simply the closure of the circuit between the sensor and the reporting circuit 302. In an exemplary embodiment, the reporting circuit 302 indicates that the TMOV 200 is in a non-operating state via a signal 306. Therefore, in an exemplary embodiment, the signal 306 is a real-time signal indicating the operating state of the TMOV 200.

[0029] In one embodiment, reporting circuit 302 is software based, including a processor and software to receive indication 304 and issue signal 306 of the state of TMOV 200. In another embodiment, reporting circuit 302 is hardware based, including circuitry to receive indication 304 and provide notification of the state of TMOV 200 via signal 306. In yet another embodiment, reporting circuit 302 includes a mix of software and hardware based components for receiving indication 304 and issuing signal 306.

[0030] In one embodiment, the reporting circuit 302 is connected to a monitor having a graphical user interface (GUI) so that the signal 306 can be transmitted to the monitor and visually received. The GUI that presents the signal 306 to the monitor is non-limiting. In another embodiment, the signal 306 is a visual indication (without using a monitor), such as a light emitting diode (LED) that illuminates in response to the indication 304 sent by the sensor 220. In another embodiment, the signal 306 is an auditory indication, such as a speaker that emits an audible sound in response to the indication 304 sent by the sensor 220. In an exemplary embodiment, the TMOV status system 300 provides a remote mechanism for obtaining the status of the TMOV 200 (via the indication 304) and communicating the status (via the signal 306). Therefore, the signal 306 enables an individual to remove, replace, or repair the TMOV 200.

[0031] In an exemplary embodiment, the novel TMOV 200 and TMOV status system 300 provide several advantages. A real-time indication 304 is provided, which in certain embodiments is the closure of the circuit between the sensor 220 and the reporting circuit 302, to indicate the operating status of the TMOV 200. Thus, remote monitoring of the TMOV 200 is possible. The integrated sensor 220 is capable of switching the reporting circuit 302. The integration of the magnet 226 with the arc barrier 206 structure provides a simple update, allowing the sensor 220 to be activated at the desired moment (i.e., when the solder melts and the TMOV becomes an open circuit that is no longer functional). Therefore, the magnet 226 moves with the arc barrier 206. In other words, the magnet 226 moves simultaneously with the arc barrier 206. In addition, the magnetic triggering method has strong anti-interference capabilities in ultra-high voltage applications. During the operation of the TMOV 200, the electrode 214, the MOV 208, and the contact pin 216 are live parts. Therefore, in ultra-high voltage applications, arcing may occur between the contact pin and the electrode. Such arcs may cause false triggering of the reporting circuit. Therefore, the novel TMOV status system 300 magnetic method without contact with any components is a more interference-resistant method compared to the contact (press or push) triggering method. In addition, the novel TMOV 200 and TMOV status system 300 are less expensive to implement and provide higher accuracy.

[0032] As used herein, an element or step described in singular form and beginning with "a" or "an" should be understood to not exclude plural elements or steps, unless such exclusion is explicitly stated. In addition, reference to "one embodiment" of the present disclosure is not meant to be interpreted as excluding the existence of other embodiments that also include the described features.

[0033] Although the present disclosure refers to certain embodiments, numerous modifications, variations and alterations may be made to the embodiments without departing from the scope and ambit of the present disclosure, as defined in one or more of the appended claims. Therefore, it is intended that the present disclosure not be limited to the described embodiments, but rather has the full scope defined by the language of the claims and equivalents.

Claims

1. A surge protection device (SPD), comprising: A metal oxide varistor (MOV) including an electrode; a spring disposed adjacent to the MOV, the spring comprising a contact pin coupled to the electrode by solder paste; an arc barrier disposed adjacent to the spring, the arc barrier sliding over the electrode in response to the solder paste melting; a magnet disposed on the arc barrier, the magnet moving simultaneously with the arc barrier; as well as A sensor for providing an indication, wherein the magnet approaches the sensor in response to the arc barrier sliding over the electrode, and wherein the sensor is protected by a coating.

2. The SPD according to claim 1, wherein: The spring moves away from the MOV in response to the solder paste melting.

3. The SPD according to claim 1, wherein: The sensor is adjacent to the MOV.

4. The SPD of claim 1, further comprising a housing, wherein: The sensor is coupled to the housing.

5. The SPD of claim 1, the arc barrier further comprising a tensioning spring, wherein the tensioning spring causes the arc barrier to slide over the electrode.

6. The SPD according to claim 1, wherein: The sensor is a reed switch.

7. The SPD according to claim 6, wherein: The indication is that the reed switch is closed.

8. The SPD according to claim 1, wherein: The sensor is coupled to a reporting circuit.

9. The SPD according to claim 1, wherein: The MOV is a thermally protected metal oxide varistor (TMOV).

10. A thermally protected metal oxide varistor (TMOV) status system, comprising: TMOV, which includes: a sensor disposed within a housing of the TMOV; and a magnet disposed on an arc barrier of the TMOV, the magnet moving in conjunction with the arc barrier, wherein the sensor provides an indication in response to the magnet being in proximity to the sensor; and A reporting circuit issues a signal in response to receiving the indication.

11. The TMOV status system according to claim 10, wherein: The sensor is attached to the housing of the TMOV.

12. The TMOV status system according to claim 10, wherein: The housing also includes an opening through which two wires pass to couple between the sensor and the reporting circuit.

13. The TMOV status system according to claim 12, wherein: The sensor is a reed switch.

14. The TMOV status system of claim 13, wherein: The indication is the closure of the reed switch.

15. The TMOV status system according to claim 10, wherein the TMOV further comprises: An MOV including an electrode; and A spring is disposed adjacent to the MOV, the spring including a contact pin connected to the electrode by solder paste.

16. The TMOV status system of claim 15, wherein: The arc barrier slides over the MOV in response to the solder paste melting, causing the magnet to approach the sensor.

17. The TMOV status system of claim 15, further comprising a second magnet, wherein the magnet is disposed on one side of the spring, and the second magnet is disposed on the arc barrier on an opposite side of the spring.

18. A thermally protected metal oxide varistor (TMOV), comprising: A metal oxide varistor (MOV) including an electrode; a spring disposed adjacent to the MOV, the spring comprising a contact pin coupled to the electrode by solder paste; an arc barrier disposed adjacent the spring, the arc barrier including a tensioning spring that causes the arc barrier to slide over the electrode in response to the solder paste melting; a magnet disposed on the arc barrier, the magnet moving simultaneously with the arc barrier; and A reed switch comprising a first blade and a second blade, wherein the magnet approaches the reed switch in response to the arc barrier moving over the electrode, and wherein the reed switch is protected by a coating.

19. The TMOV of claim 18, wherein: The first blade couples with the second blade in response to the magnet being proximate to the reed switch.

20. The TMOV of claim 19, further comprising: a housing for housing the MOV, the spring, the arc barrier, and the magnet; as well as A housing is provided for mounting about the casing, wherein the reed switch is coupled to the housing.

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