CN219144999U - Self-protection type arc shielding TCO structure for SPD overvoltage protection - Google Patents

Abstract

The utility model discloses a self-protection type arc shielding TCO structure for SPD overvoltage protection. A thermal cut-off (TCO) device assembly product for a surge protection device with overvoltage protection. The TCO device assembly may include: a TCO body including a thermal break; an output lead coupled to a first end of the thermal cutoff member; an input lead coupled to a second end of the thermal cutoff member; and an insulating sleeve disposed around the input lead, wherein the input lead and the output lead are bent so as to form a three-dimensional lead structure.

Description

Self-protection type arc shielding TCO structure for SPD overvoltage protection

Technical Field

The present disclosure relates generally to the field of voltage suppression devices, and more particularly to thermally protected metal oxide varistor devices.

Background

Metal Oxide Varistors (MOVs) are voltage dependent nonlinear devices commonly used in electronic circuits to provide transient voltage suppression. Conventional MOV devices include a metal oxide ceramic, typically in the shape of a disk, and generally planar metal electrodes connected (e.g., soldered) to opposite sides thereof. Conductive leads extend from the metal electrodes to facilitate electrical connection of the MOV devices within the circuit. The MOV body, metal electrodes and portions of the conductive leads are typically covered in a conformal coating that includes an insulating silicone base layer and an insulating varnish top layer. In some examples, a thermal cut-off (TCO) device, such as a fuse, may be arranged with the MOV to provide a Surge Protection Device (SPD) that protects against, for example, overvoltage conditions. Conventional components of SPD overvoltage protection devices may use a discrete TCO device that directly contacts the MOV (with an epoxy coating) surface to ensure that the entire SPD device remains in a fail-safe condition in the event of overheating due to overvoltage. However, when the MOV is subjected to extreme overvoltage (ultra-high overvoltage) conditions, the insulating epoxy coating of the MOV may melt, resulting in exposure of the electrodes within the MOV. Overheating from the MOV body (chip) can melt the plastic housing of the TCO device and fracture the TCO body, resulting in the exposed TCO fuse being directly connected to an electrode within the MOV. As a result, the TCO may not be able to cut off the short circuit current, and overheating from the MOV chip may then create a melted hole in the SPD device housing, resulting in a fire emanating from the housing hole.

It is with respect to these and other considerations that the present improvements would be useful.

Disclosure of Invention

This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.

Exemplary embodiments of self-shielded arc shielding Thermal Cutoff (TCO) apparatus assemblies may include: a TCO body including a thermal break; and an output lead coupled to the first end of the thermal cutoff member, an input lead coupled to the second end of the thermal cutoff member, and an insulating sleeve disposed around the input lead, wherein the input lead and the output lead are bent so as to form a three-dimensional lead structure. In various embodiments, the TCO device assembly may be coupled to a surge protection device, such as a Metal Oxide Varistor (MOV), that provides overvoltage protection. In various embodiments, the TCO device assembly can further include an insulating ceramic disk disposed on a lower surface of the TCO body.

Drawings

The drawings illustrate an exemplary method of the present disclosure, including a practical application of its principles, as follows:

FIG. 1A is a top perspective view illustrating a TCO device assembly according to an exemplary embodiment of the present disclosure;

FIG. 1B is a top perspective view, partially in section, showing the TCO device assembly of FIG. 1A;

FIG. 1C is a bottom perspective view of the TCO device assembly of FIG. 1A;

FIGS. 1D-1G illustrate top perspective views of the TCO device assembly of FIG. 1A at various stages during assembly;

fig. 2A is a top perspective view illustrating a surge protection device assembly including the TCO device assembly of fig. 1A with a housing partially removed according to an exemplary embodiment of the disclosure;

fig. 2B is a top view of the surge protection device assembly of fig. 2A;

fig. 2C is a top view of the surge protection device assembly of fig. 2B with the cover capped; and

fig. 2D is a bottom perspective view of the surge protection device assembly of fig. 2A.

Detailed Description

As used herein, an element or operation recited in the singular and proceeded with the word "a" or "an" should be understood as including the plural element or operation, unless such is explicitly stated. Furthermore, various embodiments herein have been described in the context of one or more elements or components. An element or component may comprise any structure arranged to perform certain operations. While embodiments may be described with a limited number of elements in a certain topology by way of example, embodiments may include more or fewer elements in alternative topologies as desired for a given implementation. Note that any reference to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. The appearances of the phrases "in one embodiment," "in some embodiments," and "in various embodiments" in various places in the specification are not necessarily all referring to the same embodiment.

Embodiments of self-protecting arc shielding TCO structures that can be applied to surge protection devices for overvoltage protection are described in detail herein with reference to the following figures. For convenience, this structure may be referred to herein as a "TCO device assembly.

However, the TCO device assembly may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will convey certain exemplary aspects of the TCO device assembly to those skilled in the art. In the drawings, like numbers refer to like elements throughout unless otherwise specified.

Referring to fig. 1A-1C, various views of an exemplary embodiment of a TCO device assembly product, referred to herein as a TCO device assembly 100, according to exemplary embodiments of the present disclosure are shown. For convenience and clarity, terms such as "front," "back," "top," "bottom," "upper," "lower," "above …," "below …," and the like may be used herein to describe the relative positions and orientations of the various components of the TCO device assembly 100, each with respect to the geometry and orientation of the TCO device assembly 100, as presented in fig. 1A-1C. The terminology will include the words specifically mentioned, derivatives thereof and words of similar import.

The TCO device assembly 100 may include a TCO body 102, the TCO body 102 including a thermal cutoff member 102A, which is not visible in the figures but is shown by a dashed outline. The thermal cutoff component 102A within the TCO body can be any suitable element, such as a thermal fuse. The TCO body 102 can be formed from a known polymeric material such as a plastic material. The TCO device assembly also includes an output lead 104 and an input lead 106. It will be appreciated that these leads are electrically connected to the thermal cut-off component 102A to transmit current when the TCO element 102A is operating in a normal state. Upon reaching the fusing temperature, such as the fusing temperature for the fusing material of the TCO element 102A, the TCO element 102A is designed to open or fuse, thereby providing protection to external components or systems.

As shown in fig. 1A-1C, the TCO device assembly 100 further includes an insulating tube, shown as an insulating sleeve 108 disposed about the input lead 106. In addition, the input lead 106 and the output lead 104 are bent so as to form a three-dimensional lead structure. In various embodiments, the TCO device assembly 100 may further include an insulating ceramic disk 110 disposed on a lower surface of the TCO body 102, as particularly illustrated in fig. 1C. The insulating ceramic disk 110 may be electrically insulating, but may be a relatively good thermal conductor, such as Al ₂ O ₃ . In some examples, the insulating ceramic disk 110 may be attached to the TCO body 102 by glue or resin. As discussed below, these features of the TCO device assembly 100 provide advantages in safety and reliability of operation of the TCO device assembly 100 for protecting devices such as MOVs.

Referring to fig. 1D-1G, various stages during assembly of the TCO device assembly 100 according to exemplary embodiments of the present disclosure are shown. At fig. 1D, the TCO device is received where the input lead 106 and the output lead 104 are rectilinear structures attached to the TCO body 102. For example, the TCO device depicted in fig. 1D may be a commercially available TCO device having a specific fusing temperature designed for a given application. For example, the TCO device of FIG. 1D can be designed to protect an MOV where the desired fusing temperature is 110 ℃, 115 ℃, 120 ℃, or other suitable temperature.

At fig. 1E, the input lead 106 and output lead 104 have been bent into a three-dimensional shape suitable for applications such as in an SPD assembly with an MOV. At fig. 1F, the ceramic body 110 has been attached to the lower surface of the TCO body 102. At fig. 1G, an insulating sleeve 108 has been placed around the input lead 106.

Referring to fig. 2A-2D, various views of an exemplary embodiment of the TCO device assembly 100 are shown when disposed within a surge protection system 200. The components of the TCO device assembly 100 illustrated in FIGS. 2A-2B have been previously discussed with respect to FIGS. 1A-1C. The surge protection system 200 includes a housing 204 containing the TCO device assembly 100 and an MOV structure shown as MOV 202.

MOV 202 can be used to suppress transients in many applications such as: SPD applications, uninterruptible Power Supplies (UPS), AC power taps, AC power meters, or other products. Under normal operating conditions, the AC line voltage applied to the MOV will not exceed the rated voltage of the MOV 202. Overvoltage transients exceeding these limits may occur by accident. These transient values will be clamped to the appropriate voltage level by the MOV 202 provided that the transient energy does not exceed the maximum rated value of the MOV. If the MOV 202 is subjected to a sustained abnormal overvoltage, the MOV 202 may enter thermal runaway, resulting in overheating, smoke and potentially fire, as discussed above.

Accordingly, the TCO device assembly 100 is disposed on the MOV 202 to provide enhanced protection to the MOV 202. Specifically, when the MOV 202 is subjected to an overvoltage condition, the design and components of the TCO device assembly 100 will prevent the TCO leads (output lead 104 and input lead 102) from electrically connecting (shorting) with the (upper) electrode surfaces within the MOV 202 even if the plastic body of the TCO body 102 breaks due to the MOV overheating. Such electrical isolation under MOV fault conditions ensures that the TCO device assembly 100 will reliably cut off the fault short circuit current to avoid burnout of the entire surge protection system 200. Note in particular that the insulating sleeve 108 is disposed on the input lead side (connected to the power cord) such that the insulating sleeve 108 will maintain electrical isolation from the MOV 202 electrode to the power cord. The insulating sleeve 108 thus avoids arcing or electrical connection between the input lead 106 external to the TCO body 102 and the internal electrodes of the MOV 202.

Placing the insulating ceramic disk 110 under the TCO body 102 provides isolation between the TCO body 102 and the MOV 202, in particular, maintains a safe distance (air gap) between the TCO body 102 and the MOV 202, avoiding arcing or making an electrical connection between the leads inside the TCO body 102 and the electrodes of the MOV 202. At the same time, the insulating ceramic disk 110, which has a relatively high thermal conductivity, will provide good thermal conductivity between the MOV 202 and the TCO body 102 so that the TCO element 102A can be fused or rapidly activated in the event of overheating due to overvoltage of the MOV 202.

In summary, the present embodiments provide an improved means of self-protecting arc shielding with high reliability for current interruption during MOV fault events in order to avoid catastrophic events such as fires. The TCO device assembly of the present embodiments provides a low cost product that is easy to assemble, is suitable for all voltage ratings of SPD devices, and covers low-end to high-end. For example, according to some non-limiting embodiments, the TCO device assembly may operate over a large rated voltage range, such as from 120V to 480V. The TCO device assembly of this embodiment can cover thermal protection applications for various MOV sizes (such as 14 mm diameter, 20 mm diameter, 25 mm square, 34mm square, etc.) and other electrical devices. Note that the shape of the MOV to be protected by the TCO device assembly of this embodiment can be circular, square, rectangular, or other shape. Thus, for example, the dimensions of a MOV can refer to the diameter of a circular MOV or the sides of a square MOV. The embodiments are not limited in this context.

As used herein, an element or step recited in the singular and proceeded with the word "a" or "an" should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to "one embodiment" of the present disclosure are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features.

The scope of the present disclosure is not limited to the specific embodiments described herein. Indeed, various other embodiments of and modifications to the present disclosure, in addition to those described herein, will be apparent to those of ordinary skill in the art from the foregoing description and accompanying drawings. Accordingly, such other embodiments and modifications are intended to fall within the scope of this disclosure. Furthermore, the present disclosure has been described herein in the context of particular embodiments in a particular environment for a particular purpose. Those of ordinary skill in the art will recognize that the usefulness is not limited thereto and that the present disclosure may be beneficially implemented in any number of environments for any number of purposes. Accordingly, the claims set forth below are to be construed in view of the full breadth and spirit of the present disclosure as described herein.

Claims (6)

1. A self-protecting arc shielding TCO structure for SPD overvoltage protection, characterized by comprising:

a TCO body including a thermal break feature;

an output lead coupled to a first end of the thermal cutoff member;

an input lead coupled to a second end of the thermal cutoff member; and

an insulating sleeve disposed about the input lead, wherein the input lead and the output lead are bent to form a three-dimensional lead structure.

2. The self-shielded arc shielding TCO structure of claim 1 further including an insulating ceramic disk disposed on a lower surface of the TCO body.

3. The self-protecting arc shielding TCO structure of claim 2 where the insulating ceramic disk is adapted to abut a metal oxide varistor MOV where the insulating ceramic disk separates the TCO body from the metal oxide varistor.

4. The self-protecting arc shielding TCO structure of claim 1 where the first and second portions of the input and output leads lie in a first plane and the second and third portions of the input and output leads lie in a second plane perpendicular to the first plane.

5. The self-shielded arc shielding TCO structure of claim 1 where the self-shielded arc shielding thermal cutoff TCO structure is capable of operating in a voltage range from 120V to 480V.

6. The self-shielded arc shielding TCO structure of claim 1 where the self-shielded arc shielding heat cutoff TCO structure is capable of operating at MOV sizes from 7mm to 34 mm.

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