AU638698B2 - Sectionalizer with externally mounted electronic controller - Google Patents

Description

SECTIONALIZER WITH EXTERNALLY MOUNTED ELECTRONIC CONTROLLER

Background of the Invention

1. Field of the Invention

The present invention relates generally to electronic sectionalizers and, more particularly, to an electronic sectionalizer having a conductor pro¬ vided with an electronics package mounted on the external surface thereof.

2. Discussion of the Prior Art

High voltage power distribution systems are typically comprised of a main supply line that is connected to a number of branch or lateral lines. Normally, the main line is protected near its source of power by an automatic recloser or a reclosing circuit breaker which is operable to disable the entire system downstream of the recloser if currents above a certain magnitude are detected. Automatic reclosers and reclosing circuit breakers are parti¬ cularly useful for enabling transient fault currents to clear after which time the recloser can again energize the circuit. However, if fault current conditions remain, the recloser after one or more attempts to re-energize the circuit will cease operation and cause the distribution system to remain in a deactivated state until attended by a repairman.

In the past, fuse links were often in¬ stalled at the beginning of each lateral line to protect the line and isolate it from the rest of the distribution system where over-current conditions existed only in a particular lateral line. Many problems were observed, however, in attempting to coordinate the opening characteristics of the fuse links with the reclosing apparatus and in attempting to ensure that the fuse link would not melt and open the lateral line before the reclosing apparatus had an opportunity to deactivate the entire system. As a consequence, electronic sectionalizers have been developed which instead count the number of times that the recloser opens and closes the circuit. After a specified number of current flow periods or "shots", the electronic sectionalizer disables the lateral line during a subsequent dead interval when the reclosing apparatus has opened if over-current conditions in the lateral line protected by the sec- tionalizer are detected. For additional disclosure of electonic sectionalizers, reference is hereby made to U.S. Patent No. 4,533,188 dated November 12, 1985, and to U.S Patent No. 4,768,010 dated August 30, 1988.

In the aforementioned U.S. Patent No. 4,533,188, an electronic sectionalizer is disclosed in which a metal casing provides a current path across a fuse mounting while the sectionalizer is in a conducting position. An electronic circuit inside the tube detects at least two successive current surges through the casing and, during the following dead period, actuates a chemical actuator to trip the sectionalizer out of its conducting position. By mounting the electronic circuit inside the cas¬ ing, the circuit is protected against undesirable effects of electromagnetic interference produced by the high currents and high voltages associated with the sectionalizer. However, although the internally mounted electronic circuit construction provides the advan¬ tage of protection to the circuit against electro¬ magnetic interference, this type of construction suffers numerous drawbacks. For example, by placing the electronic circuit inside the casing, it is ex¬ posed to the high temperatures present in the casing and will run hot and thus be susceptible to varia¬ tions and premature aging.

In addition, because the hollow space within the casing is dedicated to the storage of the electronic circuit, it is not possible to mount other elements of the sectionalizer inside the cas¬ ing. Such a consequence is not critical to the sec¬ tionalizer illustrated in the above-mentioned Patent No. 4,533,188, since that sectionalizer may not be reset and does not require additional elements to carry out either the release or resetting of the casing. However, it would be desirable to provide a construction which permits all necessary components of the sectionalizer, as well as any other optional components to be provided, in as compact an assembly as possible.

Another drawback of employing an internal¬ ly mounted electronic circuit is that the size of the circuit is limited to a size capable of being fitted into the internal space of the casing. Be¬ cause of this limitation, the number of features capable of use in the construction is limited by the size of the casing. Other encumbrances of the in¬ ternally mounted electronic circuit also exist. For example, the internally mounted electronic circuit precludes access to the circuit so that, once mount¬ ed in the casing, it becomes very difficult to per¬ form any programming of the circuit. In addition, it is difficult to connect the circuit to the de¬ tecting circuit employed in the sectionalizer.

Objects and Summary of the Invention

It is an object of the present invention to provide an electronic sectionalizer which employs an externally mounted electronic circuit which may be easily programmed after installation to permit optional or additional features to be employed in the sectionalizer.

Another object of the invention resides in providing a sectionalizer in which the electronic circuit is removed from the high temperature region within the casing of the conductor so that the cir¬ cuit will run cooler, and thus be less susceptible to variations and premature aging.

Further, by providing a sectionalizer having an externally mounted electronic circuit, it is a further object of the present invention to per¬ mit the interior of a conductor to be employed for other purposes such as for use in storing resetting means.

An example of an electronic sectionalizer which may be reset is illustrated in co-pending U.S Patent Application Serial No. 128,688 filed on December 4, 1987, now U.S. Patent No. 4,795,996, and entitled "Electronic Sectionalizer with Resettable Actuator". The disclosure of this co-pending appli¬ cation is incorporated herein by this express refer¬ ence and makes up a part of the present application. As can be seen from a review of the co-pending application, the interior of the conductor receives an electromagnetic actuator and a linkage system which are used for triggering the release of the conductor from the contacts of the mounting struc¬ ture of the sectionalizer in a resettable fashion. In order to provide this resettable con¬ struction, it is necessary to relocate the electro¬ nic circuit from the conventional location within the casing of the conductor. As mentioned in the

10 background, it was previously considered desirable to locate the electronic circuit within the casing of the conductor so as to protect the electronic components from the undesirable effects of electro¬ magnetic interference produced by the high currents

,₅ and high voltages associated with the sectionalizer. However, the present invention permits the use of an externally mounted electronic circuit while protect¬ ing the electronic circuit from electromagnetic interference, as well as from the harsh environment _Q surrounding the conductor.

According to one aspect of the invention, a sectionalizer apparatus includes mounting struc¬ ture including first and second electrical contacts spaced from one another and rigid electrically conductive structure having an external surface and provided with first and second electrical terminals adapted to engage the first and second electrical contacts of the mounting structure when the section¬ alizer is in a closed condition. Release means are 0 provided for releasing the electrically conductive structure from engagement with at least the first electrical contact to permit the electrically con¬ ductive structure to move from the closed position to an open position, and actuating means actuate the 5 release means. The apparatus further includes con¬ trol means for detecting a condition in the section¬ alizer and for controlling the actuator in response to the detection. The control means includes an electronic control circuit mounted to the external surface of the conductive structure. The conductive structure is capable of carrying the normal electri¬ cal current load imposed on the sectionalizer in use, and is of sufficient structural strength to support the control means and carry the compressive load applied on the conductive structure by the con¬ tacts when the structure is in the closed condition.

In its preferred form, the sectionalizer includes a tubular conductive element and the con¬ trol means includes a detector and electronic con¬ trol circuit which are both mounted to the external surface of the conductive element. In addition, a housing is preferably provided which positions the control means relative to the electrically conduc¬ tive structure and which protects the control means from exposure to the environment. The condition sensed by the control means may be a period of cur¬ rent flow including a surge of current through the electrically conductive structure followed by a cur¬ rent dead interval, and the actuator is preferably triggered after some predetermined number of current flow periods. This predetermined number may be made adjustable by providing an adjustment means on the control circuit.

By providing a sectionalizer apparatus in accordance with the invention, it is possible to position the electronic control circuit in close proximity to the detector of the control means so that relatively short connections are required be- tween the circuit and detectors, and the entire con¬ trol means may be assembled as a unit and be tested ^ prior to being installed on the sectionalizer. Thus, if a defective control circuit is detected during production of a sectionalizer, it is possible to replace only the control circuit rather than the

5 entire sectionalizer.

Brief Description of the Drawing Figures

A detailed description of a preferred embodiment of the invention is provided below with _Q reference to the attached drawing figures, wherein:

Fig. 1 is a side view of an electronic sectionalizer constructed in accordance with the present invention;

Fig. 2 is a partial side sectional view of 5 the tubular conductive member shown in Fig. 1, and the externally mounted electronic circuit;

Fig. 3 is a cross-sectional plan view of the tubular conductive member of Fig. 1;

Fig. 4 is a side view of a first alternate 0 construction of the conductive member;

Fig. 5 is a cross-sectional view of a second alternate construction of the conductive member;

Fig. 6 is a cross-sectional view of a ς third alternate construction of the conductive membe ;

Fig. 7 is a side view of a fourth alter¬ nate construction of the conductive member;

Fig. 8 is a cross-sectional view of the 0 fourth construction taken along line 8-8 of Fig. 7;

Fig. 9 is a cross-sectional view of a fifth alternate construction of the conductive mem¬ ber;

5 Fig. 10 is a cross-sectional view of a sixth alternate construction of the conductive mem¬ ber; and

Fig. 11 is a flow diagram of an electrical control circuit made for use in a sectionalizer con¬ structed in accordance with the present invention.

Detailed Description of a Preferred Embodiment

As illustrated in Fig. 1, a sectionalizer 10 is carried by a mounting assembly 12 that in¬ cludes an insulator 14 having an arm 16 for securing the assembly to a utility pole or the like. The mounting assembly 12 has an upper electrical contact 18 that includes a conductive, downward biased arm 20 having a concave detent, and a lower contact 22 spaced from the upper contact 18 and mounted on an opposite end region of the insulator 14. The lower contact 22 includes a pair of spaced, hook-shaped portions 24 (only one shown) on which the section¬ alizer 10 is carried.

The sectionalizer 10 includes an elonga¬ ted, electrically conductive structure including a conductive element 26 shown as a tube in Figs. 1-3 with an upper terminus that is received in the con¬ cave detent of the arm 20 of the upper contact 18. Release means are provided between the sectionalizer 10 and the mounting assembly 12 for releasing the conductive element 26 from engagement with at least the upper electrical contact 18 to permit the con¬ ductive element 26 to move from a closed position of the sectionalizer, such as that shown in Fig. 1, to an open position. The release means includes a trunnion member 28 disposed substantially between the two hook-shaped portions 24 of the lower contact 22 and having a pair of cylindrical pins 30 that extend horizontally outward in opposite directions and which are received in respective hook portions 24.

The trunnion member 28 is pivotally con¬ nected by means of a further pin 32 to a lower cast¬ ing 34 of the conductive element 26. The longitudi¬ nal axis of the pin 34 is parallel to the central axis of pins 30 for enabling swinging motion of the

10 trunnion member 28 relative to the conductive ele¬ ment 26 during simultaneous swinging movement of the trunnion member 28 relative to the hook portions 24 of the lower contact 22. A spring contact 36 se¬ cured to the lower casting 34 normally engages a

,,- raised portion of the trunnion member when the con¬ ductive element 26 is in its closed, current-carry¬ ing or loaded position as shown in Fig. 1, for facilitating the flow of current from the upper con¬ tact 18, along the length of the conductive element 0 26 and thereby across the trunnion member 28 to the lower contact 22.

A plunger 38 is mounted within a recess of the lower casting 34 and extends through the casting between the conductive element 26 and the trunnion 5 member 28. The plunger 38 is in turn connected to an actuating means (not shown) which may take any one of several forms. In the preferred embodiment, as disclosed in the above-mentioned co-pending application, the actuating means includes a linkage 0 system located within the tubular conductive element 26 which connects the plunger 38 to an electromagne¬ tic solenoid that is also located within the conduc¬ tive element. The solenoid includes its own power supply, such as a current transformer, and is acti- ₅ vated in response to a control means which operates in a manner more fully described below. Activation of the actuator triggers movement of the plunger thus causing relative movement between the conduc¬ tive element 26, the trunnion member 28 and the lower contact 22. As a result of this relative movement, the conductive element 26 is released from engagement with the upper contact 18 and the conduc¬ tive element moves to the open position. Because a solenoid is employed as an actuating means in this embodiment, the sectionalizer 10 is resettable and may be utilized repeatedly without replacement.

It is possible to provide other construc¬ tions of the actuating means. For example, a deto¬ nating actuator may be preferred in certain circuiti¬ stances such as where the capability of resetting the actuator is not desired or is too expensive for a given application. In this alternate embodiment, the actuator could still be located within the conductive element 26 to ensure protection of the actuator from exposure to the environment, while permitting the sectionalizer 10 to retain many of the advantages already discussed with regard to the preferred embodiment.

In Fig. 2, a control means is shown as being mounted on the external surface of the tubular conductive element. The control means includes a first current transformer 40 which serves the dual roles of a circuit power supply and a detector for sensing a condition in the conductive element 26 such as the current passing therethrough. A second current transformer 42, is also provided which serves as a power source for the actuator as dis¬ cussed above. The first and second current trans¬ formers 40, 42 are connected by leads 44, 46 to an electronic control circuit 47 provided on a printed circuit board 48. Output wires 50 extend from the actuator through an opening 52 in the conductive element 26 and are also connected to the circuit 47. In an alternate embodiment, it is possible to replace the current transformers 40, 42 with other components serving similar functions to those of the transformers. For example, the first current transformer may be replaced by some other detector, such as a Hall effect transducer, along with an alternate power supply. Such power supply might in¬ clude a non-rechargeable battery, e.g., of the lith¬ ium type, or might be constructed from a recharge¬ able battery connected with a further current trans¬ former. The second current transformer likewise could be replaced by either of these alternate power supply constructions.

The current transformers 40, 42 and con¬ trol circuit 47 are mounted within a housing 54 which positions these components relative to the ex¬ ternal surface 56 of the conductive element 26. In addition, the housing 54 also protects these compo¬ nents from exposure to the environment and from in¬ advertent bumping by linemen or others in close proximity to the sectionalizer.

As illustrated in Fig. 3, in the preferred construction of the sectionalizer, the housing 54 includes an annular body 58 formed of a potting com¬ pound, such as an epoxy resin, which is mounted on the external surface 56 of the tubular conductive element 26 and secured in place by an adhesive or other known attachment means. This housing body 58 is formed with two current transformers 40, 42 and their associated lead wires 44, 46 embedded therein as shown by Fig. 2. By constructing the housing body 58 in this manner, the two current transformers 40, 42 are securely held in position in the housing 54 and are prevented from being exposed to moisture and other environmental conditions.

An annular flange 60 is formed as a part of the body 58 and extends from one axial end of the body so as to define a cavity 62 in which the cir¬ cuit board 48 is received. The cavity 62 is closed 0 off from exposure to the environment by a weather shield 64 which extends axially of the cavity and by a snap-in cover 66. The weather shield 64 is pre¬ ferably constructed of metal-plated plastic or metal such as copper and is formed with an annular groove 5 68 therein adjacent one of its axial ends for re¬ ceiving the circuit board 48. Once the board is fitted into the groove 68 of the shield 64, the shield is fastened to an inner surface 70 of the flange, thus encapsulating the circuit board 48

20 within the housing 54. Thereafter, should it be necessary for adjustments or programming to be carried out, it is only necessary to snap out the cover 66 in order to get access to the circuit board 48. As an alternative, it is possible to partially _?c. embed the circuit board in the potting compound so that the bottom side of the board is exposed for programming as described below, or to completely embed the circuit board in the potting compound to ensure protection of the board from environmental

30 conditions. Of course, if completely embedded, the board would not be accessible for programming.

The circuit board 48 is also provided with a number of sets of output terminals 72,74 which permit programming of the circuit. For example, one

35 set of output terminals 72 may be provided on the board 48 to increase or decrease the current rating of the sectionalizer 10 in order to permit a single sectionalizer construction to be employed in differ¬ ent power distribution applications. Such program¬ ming may be carried out by repositioning a jumper connector 76 between the terminals to provide pre¬ determined changes in circuit operations.

Thus, by providing a single sectionalizer construction that is programmable, it is possible for a manufacturer or supplier to stock only one type of unit capable of use in any of a plurality of uses. For example, while it is desirable that a sectionalizer used in an underground distribution system be actuated after only one shot, it is pre¬ ferred that a sectionalizer to be employed in an overhead system be actuated after two or three shots. Either of these system requirements can be satisfied by employing a single sectionalizer con¬ struction in accordance with the invention.

Various alternate embodiments of the conductive element 26 are possible with the section¬ alizer of the present invention. For example, a conductive element 78 having a V-shaped cross sec¬ tion may be used as shown in Figs. 4 and 5. In this embodiment, a first housing 80 encases the two cur¬ rent transformers and is mounted externally of the conductive element 78 in close proximity to the con¬ trol means mounted in a separate housing 82 on the external surface of the conductive element 78. In this first alternate construction, the actuating means includes a detonating device located in the lower casting 84 of the conductive structure which must be replaced after one use. The actuator is de¬ tonated by an electrical signal delivered to the actuator from the control means by a lead wire (not shown} .

In Figs. 6-10, additional embodiments of the sectionalizer are illustrated. In Fig. 6, a conductive element 86 having an X-shaped cross section is illustrated. In this second alternate construction, a control means housing 88 is mounted within one of the V-shaped grooves of the conductive element 86. As shown in Figs. 7 and 8, a C-shaped

10 conductive element 90 includes a central longitudi¬ nal cavity in which a control means housing 92 is located, and in Fig. 9 a control means housing 94 is mounted in a longitudinal cavity of an H-shaped con¬ ductive element 96. In Fig. 10, a control means

,r housing 98 is mounted between two parallel walls of an open conductive element 100.

The operation of the sectionalizer is illustrated by the schematic diagram of Fig. 11, with the line 102 representing the conductive member

20 which passes through the current transformers 40, 42. As mentioned above, the current transformer 40 serves as the detector and power supply to the con¬ trol circuit, while the current transformer 42 acts as a power source to the actuator.

_2c The transformer 42 is employed as a power source for activating the actuator 104 and is con¬ nected to the actuator through an actuating firing circuit 106 in order to permit control of the acti¬ vation. The other transformer 40, besides serving

30 as a logic power supply 108, also provides signals used by a magnitude sensing circuit 110, a deadline detector circuit 112, and positive and negative peak detector circuits 114 in detecting when current flow periods occur. These current flow periods which are

35 sensed by the circuits 110, 112, 114 each include a current surge followed by a dead interval during which the current in the conductive element drops off. A decision circuit 116 compares the outputs of the sensing circuits 110, 112, 114 and determines when a period has occurred. Thereafter, the deci¬ sion circuit 116 counts the periods and activates the actuator firing circuit 106 when a predetermined number of periods has been detected.

One set 74 of output terminals on the circuit board 48, as shown in Fig. 2, permits ad¬ justment of the number of periods which are to be detected prior to energization of the actuator 104. Thus e.g., if the jumper connector 118 is left un- attached, the detection of three periods will trig¬ ger the energization of the actuator during a fol¬ lowing sensed dead interval. The jumper 118 may later be attached between two of the terminals to modify operation of the circuit to energize the ac¬ tuator after one, two, four or more detected periods. Thus, a variation in the program followed by the circuit is permitted resulting in more flexi¬ bility than has previously existed.

Although the invention has been described with reference to the above-described preferred embodiment, it is understood that changes may be made and equivalents employed herein without depart¬ ing from the scope of the invention as set forth in the claims. For example, although the sectionalizer has been illustrated and described as being pivot- ally mounted on the contact of the mounting assem¬ bly, it is possible to employ a sectionalizer which is mounted for linear sliding movement relative to the contact as disclosed in co-pending U.S Patent Application Serial No. 110,966 filed October 20, 1987.

Claims (17)

WHAT IS CLAIMED IS:

1. A sectionalizer apparatus comprising: mounting structure including first and second electrical contacts spaced from one another; rigid electrically conductive structure having an external surface and provided with first and second electrical terminals adapted to engage the first and second electrical contacts of the mounting struc¬ ture when the sectionalizer is in a closed condition; release means for releasing the electrically conductive structure from engagement with at least the first electrical contact to permit the electrically conductive struc¬ ture to move from the closed position to an open position; actuating means for actuating the release means; and control means for detecting a condition in the sectionalizer and for controlling the actuator in response to the detection, the control means including an electronic con¬ trol circuit mounted to the external sur¬ face of the conductive structure, said conductive structure being capable of car¬ rying the normal electrical current load imposed on the sectionalizer in use, and of sufficient structural strength to sup¬ port the control means and carry mechani¬ cal load applied on the conductive struc¬ ture by the contacts when the structure is in said closed condition.

2. The apparatus as set forth in claim

1, wherein the electrically conductive structure is a tube having a hollow interior region.

3. The apparatus as set forth in claim

2, wherein the actuating means is disposed in the hollow interior region of the tube.

4. The apparatus as set forth in claim 1, wherein the control means includes detection means for sensing the current through the conductive structure.

5. The apparatus as set forth in claim 4, wherein the detection means includes a current transformer.

6. The apparatus as set forth in claim 1, wherein the control means includes detection means for sensing the condition in the sectionali¬ zer, the detection means including a detector mount¬ ed to the external surface of the conductor.

7. The apparatus as set forth in claim 1, wherein the control means includes power means for providing power to the control circuit, the power means being mounted to the external surface of the conductor.

8. The apparatus as set forth in claim 1, further comprising housing means for positioning the control circuit relative to the electrically conductive structure and for protecting the control circuit from exposure to the environment.

9. The apparatus as set forth in claim 1, further comprising housing means for positioning the control means relative to the electrically con¬ ductive structure and for protecting the control means from exposure to the environment.

10. The apparatus as set forth in claim 9, wherein the housing means is formed of a potting compound.

10

11. The apparatus as set forth in claim 10, wherein the control means includes detection means for sensing the condition in the sectionali¬ zer, the detection means including a detector em-

,g bedded in the potting compound of the housing means.

12. The apparatus as set forth in claim 10, wherein the control means includes power means for providing power to the control circuit, the

20 power means including a current transformer which is embedded in the potting compound of the housing means.

13. The apparatus as set forth in claim

25 8, wherein the housing means includes an opening through which the control circuit is accessible.

14. The apparatus as set forth in claim

13, further comprising a cover on the opening which

20 protects the control circuit from exposure to the environment and which is manually removable to permit access to the control circuit.

35 ι 15. The apparatus as set forth in claim

14, wherein the sectionalizer is adapted to operate at a predetermined current rating, the control circuit including a circuit board having at least

5 one set of terminals adapted to permit adjustment of the current rating of the sectionalizer.

16. The apparatus as set forth in claim 1, wherein the condition sensed by the control means 0 is a current flow period including a surge of cur¬ rent through the electrically conductive structure followed by a current dead interval.

17. The apparatus as set forth in claim 5 16, wherein the actuator is triggered upon detection by the control means of a predetermined number of current flow periods the control circuit including a circuit board having at least one set of terminals adapted to permit adjustment of the predetermined 0 number of current flow periods necessary to trigger the actuating means.

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0

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