CN212341249U - Test switch unit for testing electrical devices in a substation automation system - Google Patents

Abstract

The utility model relates to a test switch unit for testing electric device in the transformer substation automation system, test switch unit (100) hold test plug (200) so that the conduction path in the CT circuit keeps apart and the short circuit. The test switch (100) unit comprises two contact elements (108,110) which are pushed apart when the test plug (200) is inserted into the test switch unit (100). Movement of the contact elements (108,110) is limited by a first pivot (102) and a second pivot (104) rigidly attached to the housing (106). When the contact elements (108,110) are separated, they push the contact extension element (132) downward. When the contact extension element (132) is in contact with the shorting bar (144), the conductive path in the CT circuit is shorted.

Description

Test switch unit for testing electrical devices in a substation automation system

Technical Field

The present invention relates generally to a substation automation system (substation automation system), and more particularly to a test switch unit for testing electrical devices in a substation automation system.

Background

The power generation and distribution system includes a large number of components and circuits. Such components and circuits are typically controllable by intelligent electronic devices (called IEDs). In operation, such components and circuitry are coupled to one or more sensors. The sensors may detect suitable operating parameters, which may be communicated to the IED. The IED, when receiving information from the sensors, can generate a large number of control signals for controlling components and circuits. The IED may be periodically tested, during which the IED may be isolated from the main current path of the power generation and distribution system using suitable testing means, such as testing switches. The test switch enables a current or voltage circuit provided in the power distribution network to be tested not physically disconnected but by isolation.

For testing, a test plug can be inserted into the test switch, which effects the opening of the trip circuit (trip circuit), the short-circuiting of the isolated voltage converter (VT) circuit and/or the current Converter (CT) circuit. Thus, testing may be performed on the IED.

Substations include a large number of test switches and circuits such as Current Transformer (CT) circuits, Voltage Transformer (VT) circuits, and the like. During testing, which may be located to one or more IEDs on the power distribution network, a test plug may be inserted into the test switch unit. It may be noted that such tests may also be performed for other types of electrical devices. Examples of such electrical devices include, but are not limited to, protective relays, switchboards (switchboards), and voltmeters. As previously discussed, such test switches, when used for testing with test plugs, help to ensure uninterrupted power supply in the power system. In addition, if a fault occurs, the test ensures that the protective relay operates and isolates the faulty section and maintains the remaining system stability.

It may also be noted that the test switch may be used for secondary injection testing (secondary injection testing) of protective relays, which involves performing such testing without causing any interference to wiring, terminals or equipment settings. As will be generally understood, most test switches lack the ability to automatically short the current circuit when the test plug is inserted and need to be manually shorted by the user prior to testing. This is not only time consuming but also unsafe when the operator is exposed to energized galvanic contact. To this end, the test switch may be designed to short circuit the CT (current transformer) secondary when the test plug is inserted. Such a short circuit may be realized when the test plug moves the pair of contact elements within the test switch apart to make contact with a shorting bar connected to an adjacent CT circuit. It may be noted that the contact with the shorting bar may have to be established before the contact elements are moved apart and the contact between them is actually broken. This may be accomplished by inserting a test plug handle (test plug handle) into the test switch to implement a "make-before-break" functionality for the CT circuit.

Typically, in current test switches, the sliding mechanism between the test switch and the test plug stem generates friction and heat, for example because the contacts in both the test switch and the test stem are of silver plated copper material. This may affect the contact dynamics during complete operation, insertion and retraction. Therefore, when the test plug shank is inserted into or withdrawn from the test switch, it may generate contact bounce (contact bounce) in the test switch due to friction between the silver-plated surface of the test plug shank and the contacts within the test switch unit. Contact bounce typically occurs because the contact element within the test switch unit is able to move in a direction approximately perpendicular to its length. Due to this degree of freedom, the contact element tends to pivot slightly about a point when the test plug shank is inserted into the test switch unit.

The occurrence of contact bounce may cause electrical imbalances within the power distribution network. For example, contact chatter may result in transient opening of the CT circuit when the test handle is inserted or retracted. Although the resulting contact bounce is only very brief, in case the circuit is opened for a long time, it can be detected by some instrument as a disconnection of the connection when the switch is tested before installation. If the contacts flutter for too long, they may allow the current transformer to emit such a high voltage that it may deleteriously cause damage or other types of damage in the transformer isolation or between the connecting wires.

Disclosure of Invention

In order to solve the above problems with previously known test switches, the above mentioned example of a test switch unit for a substation automation system is explained according to an embodiment of the invention. In one example, the test switch unit includes one or more pivots about which the contact element is movable within the test switch unit. The presence of the pivot within the test switch unit enables the pivoting behaviour of the contact element to be influenced thereby limiting the range over which the contact element can be moved, which in turn prevents contact bounce. Furthermore, the example test switch unit may be implemented without changing the structure and type of the test plug shank.

The test switch unit can be used for a CT circuit. For a CT circuit, the test switch unit may comprise at least two contact elements. In such a case, the contact elements enable isolation of the CT circuit coupled to the IED so that the IED can be tested under consideration. The test switch unit comprises pairs of contact elements which are positioned such that the first contact element is well positioned relative to the other, that is to say the second contact element. The test switch unit additionally includes a first pivot corresponding to the first contact member and a second pivot corresponding to the second contact member. The first and second contact elements may be positioned about an imaginary line extending along the length of the housing. As regards the first contact element, the first contact element is non-linear in shape and extends in the plane in which the test switch unit is present. The first contact member extends about a first pivot axis. In another example, one end of the first contact element is rigidly attached to the housing of the test switch unit. Due to the pivot provided in the test switch unit together with the contact element fixed to the body of the test switch unit, the movement of the first contact element can be limited to fewer degrees of freedom than the movement of the contact element corresponding to the previous test switch unit.

The second contact element is similar in shape and configuration to the first contact element, but is well positioned so that the second contact element appears to be a mirror image of the first contact element. The second contact element is also attached to the housing of the test switch unit, with one end fixed and the other end movable. In an example, the second contact element may further include a contact extension element disposed at a movable end of the second contact element.

In operation, in order to effect a short circuit of the CT circuit, the test switch unit will receive the test plug shank for pushing the pairs of contact elements away from each other, causing the contact extension element provided at the second contact element to be pushed down such that the contact extension element is in contact with the shorting bar. The insertion of the test handle may be effected manually. Manually moving the test handle effects separation of the contact elements and in turn movement of the contact extension elements. When the test handle is inserted, the pairs of contact elements pivot about the first and second pivots and thereby cancel the free movement of the contact elements. Since the second contact member is movable about the second pivot axis, the contact between the contact extension member and the shorting bar is prevented from rattling.

The method described eliminates the occurrence of contact chatter and overcomes any problems that may arise from positioning such a test handle for testing purposes. As explained in the next paragraph, the test switch unit provides an efficient mechanism for isolating various types of circuits with minimal effort. Furthermore, the test switch unit as illustrated is less complex and therefore will be cost-efficient and economical.

Drawings

The features, aspects, and advantages of the present invention will become better understood with regard to the following description and accompanying drawings. The use of the same reference symbols in different drawings indicates similar or identical features and components.

Fig. 1 shows a cross-sectional view of a test switch unit according to an embodiment of the present invention; and

fig. 2-4 show cross-sectional views of a test switch unit in various stages of operation according to embodiments of the present invention.

Detailed Description

The operation of the test switch unit is further explained in conjunction with the drawings. Wherever possible, the same reference numbers will be used throughout the drawings and the following description to refer to the same or like parts.

Fig. 1 shows a cross-sectional view of a test switch unit 100 according to an example of the invention. The test switch unit 100 may be installed in a test system, wherein such a test system may be used for testing Intelligent Electronic Devices (IEDs) installed within the power generation and distribution system. As mentioned above, the present illustration depicts an example test switch cell 100. Other examples may also be possible without departing from the scope of the present invention.

Returning to fig. 1, the test switch unit 100 includes a rectangular enclosure in which various components may be present. As shown, the test switch unit 100 includes a first pivot 102 and a second pivot 104 connected to a housing 106. The first pivot 102 and the second pivot 104 are rigidly attached to the housing 106 such that the first pivot 102 and the second pivot 104 extend normal to a plane in which the housing 106 extends. The test switch unit 100 additionally comprises a first contact element 108 and a second contact element 110 (together referred to as contact elements 108,110) enclosed within the housing 106. The contact elements 108,110 are positioned such that the contact elements 108,110 are placed around an imaginary line extending along the length of the housing 106. In the present example, the imaginary line is depicted as line a. As will be observed, due to the similarity in the shapes of the first contact element 108 and the second contact element 110, the contact elements 108,110 may be considered to form mirror images of each other.

Each of the contact elements 108,110 has a respective end portion 112,114, which in turn is rigidly attached to the housing 106. The structure of the contact elements 108,110 is now described with respect to the first contact element 108. The first contact element 108 includes a first linear portion 116 extending from the end portion 112. The first linear portion 116 may extend in a direction that lies parallel to or may be oblique to line a. When the first linear portion 116 is extended, the first contact element 108 is additionally bent into a first bent portion 120. The first curved portion 120 is generally semi-circular and extends from the first linear portion 116. The first curved portion 120 extends about the first pivot axis 102. Additionally along the length of the first contact element 108, the second linear portion 124 extends in the direction indicated by line a. Thereafter, the first contact element 108 is additionally bent into a second bent portion 128 which further extends from the second linear portion 124. Furthermore, the first curved component 134 of the housing 106 is located proximally with respect to the first pivot 102 such that the first curved portion 128 of the first contact element 108 abuts between the first curved component 134 and the first pivot 102 to prevent any lateral motion of the first contact element 108. As will be appreciated, such a lateral action typically occurs in previously known test switch units, in which the contact element is moved laterally, i.e. in a direction orthogonal to that direction in which the test switch shank will move when inserted.

As previously described, a substantial portion of the second contact element 110 is similar in shape and configuration and corresponds to the shape of the first contact element 108. The second contact element 110 includes a corresponding first linear portion 118 (referred to as the first linear portion 118) extending from the end portion 114. Portion 118 is similar to portion 116 of first contact element 108. The first linear portion 118 extends in a direction that is parallel to or it may be oblique to line a. When the first linear portion 118 is extended, the second contact element 110 is additionally bent into a corresponding first bent portion 122. The curved portion 122 is similar to the curved portion 120 of the first contact element 108. The first curved portion 122 of the second contact element 110 extends from the first linear portion 118. The first curved portion 122 extends about the second pivot axis. Additionally along the length of the second contact element 110, the second linear portion 126 extends in the direction indicated by line a. Thereafter, the second contact element 110 is additionally bent to form a second bent portion 130 additionally extending from the second linear portion 126. In addition, the second curved member 136 is located proximally with respect to the second pivot 104 such that the second curved portion 130 of the second contact element 110 abuts between the second curved member 136 and the second pivot 104 to prevent any lateral motion of the second contact element 110. As will be appreciated, the shape and configuration of the main portion of the second contact element 110 is similar to the shape and configuration of the first contact element 108. In addition, the second bending member 136 is located proximally with respect to the second pivot 104. In an example, the second curved member 136 is positioned such that the additional first curved portion 130 of the second contact element 110 is between the second curved member 136 and the second pivot 104. This prevents any lateral movement of the second contact element 110.

In addition to the above, the second contact 110 element additionally includes a contact extension element 132 at an end of the second curved portion 130 of the second contact element 110. The test switch unit 100 may further include a pair of plate springs (not shown in the drawings) that are in contact with the first contact member 108 and the second contact member 110, respectively. The leaf springs may accordingly provide a bias to the first and second contact elements 108 and 110. The test switch unit 100 may also be provided with a plurality of beams 142 to provide support for the first and second contact elements 108,110 and to limit their movement in the plane in which the test switch unit 100 extends. In addition, the test switch unit 100 includes a shorting bar 144 that enables electrical connection between the second contact element 110 and the shorting bar 144 when the second contact element 110 is in contact with the contact extension element 132.

The operation of the test switch unit 100 will now be described in a staged manner with reference to fig. 2-4. Through various stages, the test switch unit 100 may be used to test electrical devices within a substation system. The test switch unit 100 is used to short circuit a Current Transformer (CT) circuit within a substation while eliminating the possibility of contact bounce occurring. Additional details regarding the operation of the test switch cell 100 are provided in connection with fig. 2-4.

In operation, the test switch unit 100 can accommodate the test plug 200 such that the curved portions 128,130 of the first contact element 108 and the second contact element 110 respectively contact each other before insertion of the test plug 200, as shown in fig. 2. The test plug 200 is provided with a longitudinally extending part 202 which is finally inserted into the test switch unit 100. The component 202 additionally comprises a head portion 204, which is a leading portion of the entry of the test plug 200 into the test switch unit 100. When the test plug 200 is inserted and the head portion 204 is a distance from the point 208, the first contact element 108 and the second contact element 110 remain in contact at the point 208. When the test plug 200 is inserted inward, the contact extension element 132 contacts the lower contact surface 206 of the component 202, as shown in fig. 2. The lower contact surface 206 may additionally be provided with a metal layer that extends from a lower portion of the component 202 up to and around the head portion 204. The test plug 200 is pushed further into the test switch unit 100 where it advances further towards point 208 (as shown in fig. 2). Upon further insertion, the head portion 204 induces separation of the contact elements 108,110, as shown in fig. 3.

During operation, movement of the first contact element 108 and the second contact element 110 is limited by both the first pivot 102 and the second pivot 104. It should be noted that the movement of the contacts 108,110 about the first and second pivots 102, 104 limits the degrees of freedom of each of the pivots 102, 104 and thereby allows limited movement of the contact elements 108, 110. The lateral movement of the head portion 204 causes separation of the contact elements 108,110, thereby affecting movement of the contact extension element 132 in a downward direction, as shown in fig. 3.

Upon insertion of the test plug 200, the contact extension elements 132 contact the shorting bars 144 to isolate and short circuit conductive paths in the CT circuit, as shown in fig. 3. In one instance, the second curved portions 128,130 of the first and second contact elements 108,110, respectively, are pushed apart, breaking their contact at point 208. Additionally, prior to shorting, the test plug 200 may be inserted slightly inward to provide additional contact movement of the contact extension element 132. In one case, the shorting bar 144 is designed in such a way that it is established with an additional step (as shown in the enlarged view of fig. 3) to allow additional movement of the contact extension element 132.

In one example, the upper contact surface 210 of the component 202 is also provided with a metal layer. The metal layer is such that it extends over only a portion of the upper region of the component 202 and such that a gap 212 is formed between the lower contact surface 206 and one end of the upper contact surface 210. When the test plug 200 is inserted, the first contact element 108 contacts the lower contact surface 206, the gap 212, and finally a portion of the upper contact surface 210, while the second contact element 110 contacts the lower contact surface 206 (as shown between fig. 3-4). As previously described, the lower contact surface 206 and the upper contact surface 210 may be provided with a metal layer. Due to the metal layer, the upper contact surface 210 and the lower contact surface 206 respectively provide a contact with the contact elements 108,110 which has a low friction and thus reduces the insertion force for inserting the test plug 200 into the test switch unit 100. In addition, the test plug 200 is furthermore inserted such that the head portion 204 is in contact with the first curved parts 134,136, as shown in fig. 4. Once the test plug 200 is in contact with the first flex members 134,136, the conductive paths are shorted. As will be apparent from the above description, the present subject matter helps to eliminate any contact bounce that may occur as a result of inserting the test plug 200 into a test switch unit. This is achieved by the contact elements 108,110 pivoting about the first pivot 102 and the second pivot 104, respectively. The first pivot 102 and the second pivot 104 limit the lateral movement of the respective contact elements 108,110, thereby eliminating contact bounce of the second contact element 110 with the shorting bar 144, which may occur during insertion of the test plug 200 into the test switch unit 100.

Although examples of the disclosure have been described in language specific to structural features and/or methodological acts, it is to be understood that the appended claims are not necessarily limited to the specific features or acts described. Rather, the specific features and methods are disclosed and explained as examples of the disclosure.

Claims (9)

1. A test switch unit (100) for testing electrical devices within a substation automation system, wherein the test switch unit (100) is capable of short-circuiting current converter, CT, circuits within the substation automation system and is capable of accommodating a test plug shank (202) to isolate and short-circuit conductive paths in the CT circuits, the test switch unit (100) comprising:

a housing (106);

a first pivot (102) and a second pivot (104) rigidly attached to the housing (106), wherein the first pivot (102) and the second pivot (104) extend orthogonal to a plane in which the housing (106) extends;

a shorting bar (144);

a first contact element (108) and a second contact element (110) are enclosed within the housing (106) such that the first contact element (108) and the second contact element (110) are positioned around an imaginary line (a) extending along a length of the housing (106) with the second contact element (110), wherein each of the first contact element (108) and the second contact element (110) comprises:

an end portion (112,114), wherein the end portion (112,114) is rigidly attached to the housing (106);

a first linear portion (116,118) extending from the end portion (112, 114);

a first curved portion (120,122) extending from the first linear portion (116,118), wherein the first curved portion (120,122) extends about one of the first pivot (102) and second pivot (104) and between respective curved members (134, 136);

a second linear portion (124,126) extending from the first curved portion (120,122), wherein both the first linear portion (116,118) and the second linear portion (124,126) extend along a length and an interior of the housing (106); and

a second curved portion (128,130) additionally extending from the second linear portion (124, 126);

wherein the second contact element (110) further comprises a contact extension element (132), wherein the contact extension element (132) is provided at an end of the second curved portion (130) of the second contact element (110), and wherein the first contact element (108) and the second contact element (110) are arranged around the imaginary line.

2. The test switch unit (100) according to claim 1, further comprising a first bending member (134) located proximally with respect to the first pivot (102), wherein the first bending member (134) is positioned such that the first bending portion (120) of the first contact element (108) is between the first bending member (134) and the first pivot (102) to prevent any lateral action of the first contact element (108), wherein the lateral action occurs in a direction orthogonal to the imaginary line (a).

3. The test switch unit (100) of claim 1, wherein the second curved portion (128,130) of each of the first contact element (108) and the second contact element (110) are in contact with each other prior to insertion of the test plug shank (202).

4. The test switch unit according to claim 1, further comprising a pair of leaf springs in contact with the first contact element (108) and the second contact element (110), respectively, for biasing the first contact element (108) and the second contact element (110).

5. The test switch unit according to claim 1, wherein the contact extension element (132) will abut and remain in contact with the test plug shank (202) when the test plug shank (202) is inserted into the test switch unit (100) upon insertion of the test switch unit (100).

6. The test switch unit according to claim 1, wherein the second curved portions (128,130) of the first and second contact elements (108,110) are disengaged and pushed apart when the test plug shank (202) is fully inserted into the test switch unit (100).

7. The test switch unit (100) of claim 6, wherein each of the first contact element (108) and the second contact element (110) will pivot about the first pivot axis (102) and the second pivot axis (104), respectively, when the second curved portions (128,130) of the first contact element (108) and the second contact element (110) are pushed apart.

8. The test switch unit (100) of claim 1, wherein the housing (106) further comprises a plurality of beams (142) for supporting the first contact element (108) and the second contact element (110).

9. The test switch cell (100) of claim 1, wherein the shorting bar (144) has a stepped profile for providing additional contact movement prior to shorting the conductive path.

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