JPS6237499B2 - - Google Patents

Description

[Detailed description of the invention]

For more than 30 years prior to the present invention, the power distribution and control industry had been seeking commercially viable current-limiting circuits and disconnectors suitable for use in low-voltage power distribution systems below about 600 volts. However, this resulted in various contradictory demands. For example, a commercially viable current-limiting circuit or disconnector must (a) be operated repeatedly at its maximum short-circuit or disconnect rating without repair or replacement of any components (this is the current-limiting (b)
Temperature rises of more than 50°C shall not occur at the terminals under rated steady state conditions in accordance with applicable safety and performance standards established for circuits and disconnectors used in distribution systems below 600 volts. (which precludes the use of built-in bulk resistors for current limiting); (c) the design must be compatible with a wide range of steady-state current ratings from a few amperes to hundreds of amperes; and (d) It must have a current limiting capability comparable to that of most commonly used fused current limiters (this means that when the short circuit current is 100,000 amperes or more, the circuit will close or break in a fraction of a millisecond). (e) must be small enough to fit into existing circuits and disconnect panel panels (which have a disconnect rating-to-volume ratio that does not exceed that of conventional circuits); (f) shall use non-toxic and non-hazardous materials; (g) in the same proportion as the increase in short-circuit current; (h) be comparable in cost to existing circuit protection devices; and (i) induce large voltage transients. It must work without any problems. None of the conventional current-limiting circuits and disconnectors satisfies all of the above requirements. It is an object of the present invention to provide a current-limiting circuit shield that satisfies all of the above-mentioned requirements. Another object of the present invention is to provide a molded case; a separable first pair of contacts within the case; a pair of elongated contact blades pivotally mounted within said case, a separate pair of contact blades mounted on each and connected in series with said first pair of contacts; a pair of contact blades, the second pair of contact blades being in engagement with each other when the pair of contact blades are in a closed position; means electromagnetically operable to separate the pair of contact blades and their second pair of contacts when actuated; a resistor having a resistance value that is variable from a relatively low value to a relatively high value; and a substantial current in the contact blade pair including the respective portions to which the second contact blade pair is attached; an elongated magnetic core structure spanning both sides of said contact blade along a carrier portion and transverse thereto relative to the direction of separation of said second pair of contacts upon actuation of said electromagnetically operable means; in the direction of
and a magnetic field in a direction transverse to the arc formed between the second contact pair upon separation and in a direction transverse to the direction of current flow in the contact blade pair. a magnetic structure capable of connecting said elongated pair of contact blades to said magnetic structure to cause them to work together to separate said pair of contact blades in response to a fault current; and an interconnection means for driving the arc away from the contact pair. Preferably, in the current-limiting type circuit breaker, the resistor is made of a material having a positive temperature coefficient of resistance, and one side of the first contact pair and the second contact pair A second connecting portion is provided between the first connecting portion and the second connecting portion on the other side of the second pair of contact blades, and the interconnecting means connects one blade of the pair of contact blades to the magnetizing conductor. said one contact blade is connected in its end region to conductor means reaching said first connection portion, and in its other end region is connected to said contact blade pair via said second contact pair. one end connected to a conductor means leading to the first connection and the other end connected to a conductor means leading to the second connection; and the one contact blade and the magnetizing conductor turns each carry a substantial current within their respective lengths between opposite sides of the elongated magnetic core structure. The parts are arranged so as to extend in the same direction from one end of each. The current limiting circuit breaker preferably includes a conductor turn for the magnetic core structure, the conductor turn being in series between the first contact pair and the resistor. and the series combination of the conductor turn and the resistor is connected in parallel to the second contact. Another object of the present invention is to provide a molded case, a magnetic core within the case, and a magnetic core within the case and generally spaced apart from the magnetic core, the magnetic core being provided with a predetermined amount of magnetic flux. an armature that can be attracted toward the magnetic core when the a conductor device within the case and associated with the magnetic core; and a conductor device within the case and associated with the magnetic core. , including first and second conductor turns for the magnetic core, the second conductor turn connected in parallel with the contact pair, and the first conductor turn connected to the contact pair. are connected in series and are also connected in series with the second conductor turning section, and the first conductor turning section is connected in series when the electrical circuit breaking device is energized and the contact pair is in the closed position. A magnetic flux is generated in the magnetic core, and the first and second conductor turns are energized by the electric circuit breaking device to attract the armature toward the magnetic core, so that the contact pair The conductor device is configured to additionally generate a magnetic flux in the magnetic core when the magnetic core is separated, and the conductor device further includes an additional conductor in parallel with the first conductor turn, and the magnetic core and the electric machine. An object of the present invention is to provide an electromagnetically actuated electric circuit breaking device characterized in that it includes a box-shaped conductor surrounding the conductor and electrically connected to the first conductor turning portion. Another object of the present invention is to provide a molded case, a molded movable contact blade mounting crossbar pivotally mounted within the case, and a molded movable contact blade mounting crossbar mounted on the mounting crossbar. a movable contact blade;
electromagnetically actuatable means operative to separate the movable contact blade from the fixed contact when actuated, the movable contact blade tapered to one end by a tapered mounting tongue; including;
The tapered mounting tongue extends completely through the mounting crossbar from one side, and the one end is pierced by a retaining plate on the other side. That's true. Other objects and features will become apparent as the following specification is read with reference to the accompanying drawings. Referring to the drawings, FIGS. 1, 2, and 34 illustrate a three-pole current-limiting circuit breaker 40 constructed in accordance with the present invention. The circuit breaker 40 is a molded base part 41
and a complementary molded cover 42. The base portion 41 and the cover 42 each have a pair of outer walls and a pair of spaced intermediate walls, and three chambers 44, 45 and 46 (second
Figure) is formed. The structure of the central pole of the circuit breaker 40 disposed in the central chamber 45 is shown in FIG. A line terminal and fixed contact assembly 48 is shown near the left hand end of FIG. Assembly 48 is best shown in FIGS. 3 through 6 and includes terminal member 49.
and a fixed contact mounting member 50 pivotally coupled by pin 51 and electrically interconnected with terminal member 49 by braided wire cable 52 . Terminal member 49 includes a first U-shaped portion including a curved portion 49a and a pair of spaced apart legs 49b and 49.
c, and the ends of the legs 49b and 49c are connected to the second U.
The second U-shaped portion is fused to the spaced pair of legs 49d and 49e of the shaped portion, respectively;
Two tab portions 49f and 4 extend from 9e, respectively.
It has a divided curved part formed by 9g. The mounting tab portion 49h has a through hole 49i, and the leg portion 49b
and 49c, and protrudes from the curved portion 49a in a perpendicular direction. Similarly, member 50 has a curved portion 50a as a first U-shaped portion and a pair of spaced apart legs 50b and 50c.
The legs 50b and 50c have ears 50b and 50e extending laterally, respectively, a leg 50f of a second U-shaped portion extending from the curved part 50a to the curved part 50g, and a position opposite to the leg 50f. Legs 50
h. Legs 49d, 49e and ears 50
d and 50e have holes for receiving pins 51. The cable 52 has a tab portion 49 at one end.
f, the other end is welded to the tab portion 49g,
The central portion is welded to the curved portion 50a.
Fixed main contact 53 and arc generating contact 54
are fixed to the leg portion 50h in contact with each other. The leg portion 50f is a retaining screw 5 for the contact pressure spring 57.
6 (FIG. 1). The internally threaded sleeve 58 is inserted into the mounting tab portion 49h at the hole 49i, and is attached to the base portion 41.
It is arranged in the mounting pad portion 41a with a hole.
A screw 59 screwed into the sleeve 48 fixes the holed connector body 60 to the tab portion 40h. Connector body 60 has a suitable wire or cable receiving hole and is provided with an internally threaded hole for receiving a set screw 61. A similar terminal and fixed contact assembly 48 is provided in chamber 4.
4 and 46, respectively. A crossbar 63 for the blades extends laterally through the central chamber 45 into the outer chambers 44,46. A groove for receiving a cross bar 63 is provided in the intermediate wall of the base portion 41, and a bracket 64 (FIGS. 2 and 34) fixed to the base portion 41 of the chamber 44 and the base of the chamber 46 are provided. Opposedly formed brackets 55 (FIG. 2) fixed to section 41 are provided to pivotally support crossbar 63. Three movable contact blades 67, one for each pole
It is attached directly to a crossbar 63 made of molded plastic material and provided with reinforcing metal inserts 68 (FIGS. 9 and 10). Machining recesses, such as recesses 63a and 63b (FIG. 9), are provided at appropriate locations on crossbar 63 to hold the crossbar during assembly of blade 67 to crossbar 63. Each blade 67 includes a pair of shouldered portions 67a, 67b (FIG. 10). These shouldered portions abut against the cross bar 63, and from these shouldered portions, a tapered mounting tongue portion 67c penetrates through the cross bar 63 and the retaining plate 69 that pierces it. Each blade 67 is provided with a movable contact 70 for engagement with an associated one of the fixed main contacts 53. Actuation mechanisms for crossbar 63 and blade 67 are provided in central chamber 45 (FIG. 1). Portions of the actuation mechanism are best shown in FIGS. 7 and 8 in the tripped position. Two frame members 72 and 73 (FIGS. 2, 7, and 8) formed opposite to each other are fixed to the base portion 41, and the bracket 6 is fixed to the base portion 41.
Crossbar 63 at 73a with 4 and 66
(the eighth
figure). The frame member 73 includes an arc 73b (FIG. 7) extending toward the frame member 72, and has a bent ear portion 73c for attachment at its free end.
Pin 74 is adjacent to one end of ear 73c and is attached to a corresponding mounting ear (not shown) of frame member 72.
attached adjacent to the other end. A releasable latch cradle member or trip lever 76 is pivotally mounted adjacent one end of pin 74. Two inner toggle links 78 and 79 are pivotally mounted adjacent the ends of a pin 80 with their inner ends attached to the central pole blade 67. Two outer toggle links 82 and 83 are pivotally mounted adjacent opposite ends of a pin 84 that has their respective outer ends attached to the trip lever 76. The outer end portions of links 78 and 79 and the inner end portions of links 82 and 83 are pivotally interconnected by an elongated toggle pin 85, and the inner end portions of links 82 and 83 are connected to the outer end portions of links 78 and 79. are staggered from each other to span. The handle extension is formed by two handle plate members 86 and 87, respectively, which are pivotally connected to a pair of pins 88 and 89 located in frame members 72 and 73, respectively. The handle plate member has a pair of spring mooring pins 9
1,92 and a reset pin 93. The toggle pin 85 has a pair of spring hook members 95 and 9 pivotally mounted adjacent to each end of the toggle pin 85.
6. The tension spring 97 (FIG. 2) has an outer end connected to the pin 91 and an inner end (not shown) connected to the dockle pin 85.
is fixed to member 95 on one side of the tension spring 98 .
(FIG. 7), the outer end is fixed to a pin 92 and the inner end is fixed to a member 95 on the other side of the toggle pin 85. Similarly, tension spring 99 (FIGS. 2 and 8)
is fixed at its outer end to a pin 91 and at its inner end to a member 96 on one side of the toggle pin 85, and is attached to a pull end spring 100.
(FIGS. 7 and 8), the outer end is attached to the pin 92 and the inner end (not shown) is attached to the toggle pin 85 on the other side of the member 9.
It is fixed at 6. Spring 97, 98, 99, 1
00 connects the toggle pin 85 to the outer toggle pins 82, 8
It is held in the open grooved inner end of 3. A retaining clip 102 is secured to the arm portion 73b of the frame member 73 and to the corresponding arm portion (not shown) of the frame member 72, and at the end of the opening movement the shock absorbing material 103 for the central pole blade 67 is secured.
(Fig. 8) is held. The frame member 73 includes an arm portion 73d (FIG. 8) having a semicircular recess 73e. Frame member 72 is similarly formed. Thermal operation common trip rod 105 (Fig. 1, Fig. 2, Fig. 11, Fig. 12)
and FIG. 34) are pivotally attached to the frame member 73 in a recess 73e, and are pivotally attached to the frame member 72 in a similar recess in the arm member 72d of the frame member 72 (FIG. 2). The generally L-shaped thermal trip lever 106, best shown in FIG. 12, includes a hole 106a that allows the
A pin 107 (FIG. 1, FIG. 2,
7 and 8). Pin 108 (No. 8) having enlarged head 108a (Fig. 7)
) is received in hole 106b (FIG. 12) of thermal trip lever 106 and attached to frame member 72 to limit pivoting movement of trip lever 106 and axial movement along pin 107. to prevent A molded plastic actuating handle 110 (FIGS. 1 and 2) passes through a hole in cover 42 and is recessed at its enlarged inner end so that pin 91,
92 and the outer ends of the handle plate members 86 and 87 are accommodated therein. Each of the two outer poles has a central pole pin 10.
7, but one end is placed in a suitable groove in the outer wall of the base part 41 and the other end is placed in the bracket 64, 6.
6 are provided with pins 107 (FIGS. 2 and 34) attached to each one of them. 3 pins 10
7 has a magnetic core holder 111 and an armature plate 112 pivotally mounted thereto. Each holder 111
carries a generally U-shaped magnetic core 113 having opposed leg portions fixed to each of its spaced sides. As shown in FIGS. 1 and 34, the holder 1
11 is each side part (only one side part is shown)
is generally in the shape of an inverted "Y", one leg of which is pivoted on pin 107 and the other leg is connected to a corresponding leg on the other side by a rear plate having a gap adjustment screw 115. There is. Each screw 115 extends through the rear wall portion of base portion 41 and has a compression spring 116 attached thereto. By rotating the screw 115, the air gap between the free end of the leg portion of the magnetic core 113 and the armature plate 112 can be adjusted. Each armature plate 112 has a pair of opposed bent ears 1
12a, each ear 112a is spaced inwardly from the side of each magnetic core holder 111, and each ear 112a is spaced apart from each pin 1
07 and is aligned with the opening in the opposing ear. As shown in FIG. 2, the right hand side of each holder 111 has each pin 107
The right ear portion of each armature plate 112 is similarly offset from the holder 111 at the portion attached to the holder 111.
They are offset from each other so that they are not covered. Therefore, in FIG. 2, only the left ear portion 112a of each armature plate 112 is visible. Each armature plate 11
The free end portion of 2 is fitted with a pair of rivets 117 (a second
(Fig.) is fixed. Central pole armature plate 112
is bored to receive the free end portion of the trip lever 76, thereby releasably latching the trip lever as shown in FIG. The three armature plates 112 and the common trip rod 118 are arranged in the two outer chambers 44 and 46, respectively, and are fixed at one end to each armature plate 112 and at the other end to the brackets 64 and 66, respectively. The trip lever 76 is biased toward the latched position by a pair of tension springs 120 (FIGS. 2 and 34). The chambers 44, 46 and 46 are respectively located in the base portion 4.
a common trip rod 105 mounted in a suitable groove in the wall of 1 and from each armature plate 112 on its opposite side;
a barrier plate 122 extending into cover 42 adjacent to
(Fig. 1 and Fig. 34). Figure 11 and 1
As best shown in FIG. 2, latch plate 123 is secured to common trip rod 105 by rivets 124. Thermal trip lever 106 has hole 106
c and a piercing portion 106d, and the hole is partially located in the piercing portion. A tension spring 125 (FIGS. 1 and 2) is anchored at one end to the piercing portion 106d in the hole 106c and at the other end to the barrier plate 122 in the central chamber 45 to provide a thermal release lever 106.
is biased clockwise around pin 107.
The barrier plate 122 is omitted in FIG. Each barrier plate 122 has a hook portion 122a (FIGS. 1 and 3).
4), and within each of the two outer chambers 44 and 46, a compression spring 126 (FIG. 34) is provided with one end of the spring 126 (FIG. 34) in each hook portion 122a and the other end in the appropriate position of the common trip rod 105. The trip rods 105 are provided at respective locations and attached on the trip rods 105.
and latch plate 123 relative to thermal release lever 106 toward the latched position. The trip pushbutton 128 (FIG. 34) typically has a compression spring 129 mounted to keep the button flush with the surface of the cover 42 and, when pushed inward, releases the common tripping bar 118. 1 to move the armature plate 112 of the central chamber 45 clockwise in FIG. 1 toward the unlatched position with respect to the trip lever 76. Chambers 44, 45 and 46 contain fixed contacts 53, 54 and movable contacts 70 of each pole, respectively.
A plurality of approximately O-shaped plates 13 arranged around the
0 and a plurality of generally U-shaped plates 131. Field magnet assembly 1973
It is coated with an arc quenching material such as that described in U.S. Pat. Further, each chamber includes a plurality of metal arc plates 134, best shown in FIG. 33, and a pair of ventilation plates 1 formed of an insulating material.
35, 136. The arc quenching material is used to coat other elements of the invention that will be described later. Its function is to help generate a medium within the arc chamber that rapidly restores the dielectric strength in the air gap. An example of a suitable material is a filler containing zinc borate hydrate in a dimethyl silicone resin in a weight ratio between 40% and 56% by weight. A more detailed description of such arc quenching materials, as well as additional examples, can be found in the aforementioned U.S. patent application no.
It is mentioned in the specification of No. 364596. In each chamber, the movable contact blade 67 is connected to a generally U-shaped conductor 139 fixed to the base portion 41 by a pair of screws 140, 141 at the curved portion.
via a flexible braided cable 138 (FIGS. 1 and 34). conductor 139
The other leg of the U-shaped magnetic core 113 is fixed to the base part 41 by a screw 143 and is fixed to a conductor 142 extending along the barrier plate 122 between the legs of the U-shaped magnetic core 113 . A generally L-shaped bimetallic strip 145 is secured at one end to the curved portion of the U-shaped conductor 139. The common trip rod 105 is provided with a total of three operating legs 105a, one provided in each of the chambers 44, 45, and 46, and in FIGS. Only the operating leg 105a is shown. Bimetal strip 145 in each room
The self-retaining end portions of the actuating legs 105a engage the respective actuating legs 105a, and when a moderate overload current connected to the conductor 139 flows, the bimetallic strip 145 is sufficiently heated to cause the actuating legs 105a to move as shown in FIGS. Pivot counterclockwise as seen in Figure 34. At this time, the inside of the L-shape of the bimetal strip expands to a large extent. By that,
The thermal trip lever 106 in the central chamber 45 is released from the latch plate 123 on the thermally actuated common trip rod 105 and under the influence of the tension spring 125 strikes the common trip rod 118, causing each armature plate 112 to Pivot clockwise as viewed in FIGS. 1 and 34 about the respective pins 107. Thereby, the central chamber 4
The tripping lever 76 in 5 is released to cause the three movable contact blades 67 to move open. If the fault current is higher than the moderate overload current on either conductor 14
2, each magnet 113 touches its armature plate 11
2, all three armature plates 112 pivot clockwise to release the trip lever 76 and the contact blade 67. Pressing the button 128 also causes the common trip rod 118 and the three armature plates 112 to pivot clockwise, causing the trip lever 76 to pivot clockwise.
to open the contact blade 67. Each end of each conductor 142 opposite to the end fixed by screw 143 is connected to a box-shaped conductor by screw 146 (FIGS. 1, 2, and 34) as shown in FIGS. 13 to 16. 148 flat L-shaped band 148a. The conductor 148 is connected to the band portion 14
8a, an end 148b, and a pair of spaced apart sides 1
48c, 148d, and a split end, the split end including a tab portion 148e extending from side portion 148c and a tab portion 148f extending from side portion 148c. Each side portion is generally square except that side portion 148c includes a mounting tab portion 148g that extends toward base portion 41 during assembly. In each of the chambers 44, 45 and 46,
The conductor 150 includes an L-shaped portion 150a,
The L-shaped portion 150a is secured at the end of its long leg to a tab extending from the short leg of the band 148a, and is connected at the end of its short leg to one end of the band 150b. , both ends of this band portion 150b are fixed to tab portions 148e and 148f, respectively. The flexible braided cable 151 has a conductor 1 at one end.
50 and attached at the other end to current limiting auxiliary contact means which includes a movable contact blade 152 (FIGS. 1 and 34) having a contact 153. The blade 152 is the contact 15
It cooperates with another movable contact blade 154 having 5. In each chamber 44, 45, 46 there are figures 17 to 19.
A mechanism is provided for actuating the blades 152, 154 as best shown in the figures. A generally U-shaped laminated magnetic core 156 is connected to a box-shaped conductor 148 (FIGS. 1 and 34).
) and its core 15
Reference numeral 6 denotes a pair of spaced apart legs 1 that straddle the band portion 148a.
56a, 156b (Fig. 17), and a pair of shoulders 156c, 156d (17th
Figure). Roughly U-shaped laminated armature 158
(Figs. 17 to 19) are arranged in the inner part of the box-shaped conductor 148 (Figs. 1 and 34), and its relatively short pair of legs 156a, 15
6b (FIGS. 17 and 19) are arranged facing each other and spaced apart from each other. An armature pin support plate 160 is provided between legs 158a and 158b. Armature 1
58 has a hole provided in the center of its curved portion, which hole connects the inner enlarged shoulder of the armature pin 161 to the armature 1.
Threaded nut 16 for fixing inside 58
2 to match the hole in the support plate 160 for receiving the externally threaded stud portion of the armature pin 161.
The armature pin 161 has a pair of opposed flat portions at its inner ends and has two spaced apart links 16
3 and 164 are pivotably mounted on their flat portions by pins 165. Links 163 and 164
pin 166 engaged in a groove in the edge of blade 152 facing blade 154 and blade 154 facing blade 152;
pin 167 which normally engages the edge of the.
Blade 152 is pivotally connected to pin 168 received in hole 169 (FIG. 17), and blade 154 is pivotally connected to pin 170 received in hole 171. Pivot pins 168 and 170 are provided on opposite sides of armature pin 161, and their ends are connected to a pair of molded inner casing sections 173 and 174 (FIG. 19) secured together by a plurality of rivets 175. Each has been accepted. Casing part 173
The compression spring 17 provided at and 174 is connected to the armature pin 16
1, supporting the blade 152 and biasing it towards the closed position, i.e. clockwise in FIG.
The blade 152 is supported by a pin 166, and a pin 167 supports the blade 154 and urges it toward the closed position, ie, counterclockwise in FIG. 18.
Spring 176 is a return spring for armature 158 and armature pin 161. Shield 177 with forked end spanning links 163 and 164
(FIGS. 18 and 19) between the blades 152 and 154, mainly in the casing parts 173, 174.
provided. Appropriate openings are provided in the casing portions 173, 174 for the armature pins 161, and in the cables 15.
1, contact blades 152, 154, and a flexible braided cable 178 fixed to the blades 154. Side portions 148c and 148d of box-shaped conductor 148 engage casing portions 173 and 174, respectively, and attach mounting tab portion 148.
g (FIGS. 15 and 16) is a casing portion 17 such as a boss 173a, only one of which is shown in FIG. 19.
It is provided between a pair of bosses on 3. The contact end portions of the blades 152 and 154 are connected to the casings 173 and 17.
4, a piece of shock absorbing material 180 (FIG. 18) is provided on the casing adjacent to the blade 152 to dampen its opening movement. A generally rectangular magnetic core structure 181 surrounds the contact end portions of blades 152 and 154 that extend outwardly of casings 173,174. The magnetic core structure 181 is best shown in FIGS. 23-25, with two identical schematic L
It includes multi-layer magnetic cores 182 and 183. The magnetic cores 182 and 183 are magnetic core 1 as shown in the figure.
The end surface of the long leg portion 182a of 82 is brought into contact with the inner surface of the short leg portion 183b of the magnetic core 183, and the magnetic core 1
The end face of the long leg portion 183a of the magnetic core 183 is placed in contact with the inner surface of the short leg portion 182a of the magnetic core 182. Magnetic cores 182 and 183 are each coated with an arc quenching material such as that described in the aforementioned U.S. patent application Ser. No. 364,596;
These additional pieces of material are adhesively secured to the inside surface of the L-shaped assembly as shown in FIGS. 23 and 24. The magnetic cores 182 and 183 can also be generally U-shaped, C-shaped, or J-shaped. In each of chambers 44, 45 and 46,
The other end of the cable 178 connected to the blade 154 at one end is electrically connected to one end of a terminal strip member 184 as shown in FIGS. 26 to 29.
A terminal member 186 is fixed to the other end of 4. Terminal member 186 is similar to terminal member 49 and includes a curved portion 186a as a first U-shaped portion and a pair of spaced apart legs 186b and 186c as a second U-shaped portion.
a pair of spaced apart legs 186d as a U-shaped portion of the
and 186e, and a split curved portion formed by two tab portions 186f and 186g extending therefrom, respectively, and the pair of legs 186b, 186c of the first U-shaped portion are connected to the legs of the second U-shaped portion. It fuses with a pair of leg portions 186d and 186e at right angles, respectively. Tab parts 186f and 186g are terminal strip member 1
It is fixed at 84. Legs 186b and 186c
A mounting tab portion 186h projects perpendicularly from the curved portion 186a in the opposite direction, and has a through hole 186i formed therein. A sleeve 58 (FIGS. 1 and 34) with an internal thread similar to that inserted into the tab portion 49h is inserted into the hole 18.
6i, each is pierced by the mounting tab portion 186h of the terminal member 186, and placed in the holed mounting pad portion 41b of the base portion 41. A screw 59 screwed into the sleeve 58 fixes the holed connector body 60 to the tab portion 186h. Connector body 60 is identical to that secured to tab portion 49h and includes an internally threaded hole for receiving set screw 61. In each of chambers 44, 45 and 46,
Conductor 188 (FIGS. 13-16) includes a band 188 extending between legs 156a and 156b of magnetic core 156 and tab portion 188a secured to the end of band 150b adjacent to tab portions 148e and 148f.
b (FIGS. 1 and 34), an offset portion 188c extending approximately parallel to the tab portion 188a, and a short leg that extends through the magnetic core assembly 181 formed by the two L-shaped magnetic cores 182 and 183. Section 182b
It has a band portion 188d extending along the inside of the.
A strip member 189 of arc quenching material as described in the above-referenced U.S. Patent Application No. 364,596.
is adhesively fixed to the side surface of the band portion 188d facing the contact blade 152. Conductor 190 includes a bendable tab portion 190a secured to the end of band 188d and extending from band 190b. The band portion 190b is the magnetic core 18
The long leg 182a extends parallel to the end face of the long leg 182a, and is connected at right angles to a band 190c running somewhat diagonally across the outside of the long leg 182a. The band portion 190c is attached to the base portion 41
An offset connection tab portion 19 with a hole provided in a hole extending along the rear wall and penetrating the rear wall of the base portion 41
It is coupled at right angles to the band portion 190d having an angle 0e.
A fixing member 191 with an internal thread is connected to a connecting tab portion 190.
It is fixed at e. Opposing the chambers 44, 45 and 46, the rear wall of the base part 41 has three shallow recesses 44a, 45a on the rear side.
and 46a (Fig. 2), and each recess is provided with a filling material 19.
3. The resistor 192 is preferably filled with a ceramic composite having good thermal conductivity properties, such as alumina or silica-based ceramic. A thin plastic cover 194 is placed in the recess of the base part 41 and adhesively secured, covering all the padding material in the three recesses 44a, 45a and 46a. The resistor 192 in each recess is made of a material having a positive temperature coefficient of resistance, preferably substantially pure iron wire with chrome plating. Resistor 192 is shown in FIGS. 20 through 22. An important feature of resistor 192 is that its resistance value can vary from fairly low values to high values. The resistor 19 has a positive temperature coefficient of resistance and is made of substantially pure iron.
Other materials that can be used as 2 include tungsten, nickel, cobalt, and alloys or metal compounds of these materials with other materials such as cobalt iron and zirconium diboride. In these materials, resistance is a direct function of temperature. As shown in FIG. 20, resistor 192 terminates at each end in a flat, generally P-shaped section including a straight section of length "X" to which electrodes are attached for electroplating with a chromium-containing solution. After electroplating,
The electrode terminal portion is cut away, as shown by the dashed line for one end in Figure 21, and the remainder of the flat end is aligned with the plane containing the axis of the circular wire, as shown in Figure 22. There is. In each of the recesses 44a, 45a and 46a, one end 192a of each resistor 192 (FIG. 20) is connected to a screw 195 (FIGS. 1 and 34).
The tab portion 192e (13th
), and the other end 192b is fixed to the screw 196.
is fixed to a tab portion 197a with a connection hole of a conductor 197 (FIGS. 26 to 29).
A fixing tool 198 with an internal thread is attached to the connection tab portion 19
It is fixed at 7a. The conductor 197 includes a band portion 197b that extends perpendicularly along the end of the short leg portion 183b of the magnetic core 183 to the connection tab portion 197a, and is joined at a right angle to a band portion 197c that extends along the end surface of the core 183. . The bent tab portion 197d extending from the band portion 197c is connected to the short leg portion 1 of the magnetic core 183.
It is fixed to a conductor 199 having a band 199a passing through the magnetic core structure 181 along the inside of the magnetic core structure 83b. The offset portion 199b is the terminal strip member 1
The band portion 199a is attached to the tab portion 199c fixed to the
A cable 178 is connected to the tab portion 199c. A strip 200 of arc quenching material such as that described in the specification of U.S. Pat.
It is adhesively fixed to the side surface of 9a. In each of chambers 44, 45 and 46,
Arc chute 2 for contacts 153 and 155
02 (FIGS. 1 and 34) is the magnetic core structure 18
1. arc shoot 202
is shown in FIGS. 30-32 and includes a pair of molded casing portions 203 and 204 secured together by a plurality of rivets 205. Each of the casing parts 203 and 204 has an arc chute 202 on the side facing the other casing part, for example, an inner recess 203a and an outer recess 203b (FIG. 32) in the casing part 203.
A pair of recesses are provided for providing a pair of passageways through the recess. Each casing part has a groove formed in the wall of each recess facing the other casing part, each groove having a third
As shown in FIG. 3, an arc plate 134 is fixed with adhesive. The ventilation plate 206 connects the casing parts 203 and 2
A ventilation plate 207 is adhesively fixed to the casing parts 203 and 204, and a ventilation plate 207 is adhesively fixed to the casing parts 203 and 204. 40 covers 42. From the contact side of the arc chute, the arc plate 13 in the inner recess 203a
4 is inclined toward the rear wall of the base portion 41, and the arc plate 134 in the outer recess 203b is inclined toward the front wall of the cover 42. Casing part 204
The inner arc plates 134 are similarly inclined, but they are aligned with the casing portion 203 as shown in FIG.
They are shifted differently from each other with respect to the inner arc plate 134. In each of chambers 44, 45 and 46,
When contacts 153 and 155 close, conductor 142
A portion of the current from the L-shaped portion 150 of the conductor 150
a to the cable 151, and the remaining current passes through the band 148a to the box-shaped conductor 148 and the conductor 150.
It flows to the cable 151 through the band portion 150b.
From cable 151, the entire, i.e. remixed, current flows to contact blade 152, contact 153 and 1.
55, contact blade 154 flows through cable 178 and terminal strip member 184 to terminal member 186. The band portion 148a and the magnetic core 156 in each chamber form an electromagnet. The magnetic core 113 is the armature plate 11
If the fault current is greater than the current that attracts band 1
48a, the magnetic core 156 is connected to the plate 160,
Armature pin 161, nut 162, link 163
and 164 and the pins 165, 166 and 167 to attract the armature 158. Pin 166 pivots blade 152 about pin 168 toward the open position, pin 170 releases blade 154,
The blade 154 is allowed to pivot freely about the pin 170 towards the open position under the influence of the repulsive force between the two blades due to the current path through the blade. Although blades 152 and 154 are also moved away from each other by magnetic forces induced by the current flowing therethrough, they constitute partial conductor turns for magnetic core structure 181. Please be careful.
Contacts 153 and 155 are thus separated and switch the current path through resistor 192. A circuit passing through the L-shaped portion 150a of the conductor,
Conductor 1 including a circuit parallel to the circuit passing through conductor band 148a, conductor 148, and conductor band 150b
42 and cable 151 until a threshold fault current greater than or equal to a preselected magnitude exists causing magnetic core 156 to attract armature 158 and open contacts 153 and 155. A shunt means is provided that provides sufficient current to prevent current limiting contacts 153 and 155 from opening. According to this circuit configuration and electromagnetic characteristics, it is possible to prevent current-limiting contacts 153 and 155 from separating at a threshold value of 1000 amperes or less, for example. When contacts 153 and 155 are separated, conductor 14
A portion of the current from 2 flows through the L-shaped portion 15 of the conductor 150.
0a and the band portion 150b to the conductor 188,
The remaining current passes through the band 148a to the box-shaped conductor 148.
to conductor 188. The recombined current then flows through conductors 188 and 190, resistor 192, conductors 197 and 199, terminal strip member 184, and to terminal member 186. Preferably, the current-limiting contact does not operate in the thermal overload region, but only in the fairly high range of fault currents or in short-circuit conditions. Within the thermal overload region, one or more bimetallic strips 145 operate to trip the circuit or disconnect and open the main contacts 53 and 54, as described above. In the region just above the thermal overload region, the fault current is still fairly low, but large enough to attract one or more armature plates 112 and open main contacts 53 and 54, as described above. It is. Such fault current is less than the shearing capability provided by magnetic core 156 attracting armature 158 to separate main contacts 53 and 54. The fault current just above this area is caused by the magnetic core 156 attracting the armature 158 and pin 161, causing the current limiting contacts 153 and 155 to
is sufficient to open up the As the current decays, the magnetic force also decays. Contacts 153 and 1
Compression spring 176 biasing 55 to the closed position
tends to overwhelm the decaying current which causes these contacts to reclose, even though shorting arcs are still present in the small gaps between these contacts. This effect often causes contact welding. To solve this problem, an additional or auxiliary magnetism generating swivel portion 188b is provided in series with the current limiting resistor 192. While the fault current is still flowing through resistor 192, magnetic core 156 is sufficiently energized to attract armature 158 and keep contacts 153 and 155 separated. In each chamber, when contacts 153 and 155 are closed, band 148a becomes the only active conductor turn to core 156, with a portion of the current flowing through it and the rest flowing in an L-shape. flow through the shunt conductor created by section 150a. When contacts 153 and 155 are open, band portion 188b
forms an additional conductor turn that carries the entire current, while the band 148a acts as a conductor turn that carries a portion of the current. Additional conductor turning section 1
88b initially moves blades 152 and 154 with a current less than that required to move blades 152 and 154 to the open position.
and 154 in the open position. The fault current flows through resistor 192 until blades 152 and 154 are returned to the closed position under the influence of spring 176.
is consumed, and the blade 67 is opened. In each of chambers 44, 45 and 46, band portions 188d and 199a constitute a conductor turn portion of magnetic core structure 181. Furthermore, the contact blade 152
and 154 constitute a partial conductor turning portion of the magnetic core structure 181. Contact blades 152 and 154
moves to the open position and an arc 208 is formed between the open contacts 153 and 155.
The magnetic field created by the current passing through the partial conductor turns of contact blades 152 and 154 acts on arc 208 to drive the arc toward arc chute 202 with staggered angled arc plates 134. Once the arc is interrupted, current is transferred to the aforementioned current path through resistor 192, and the current through conductor turns 188d and 199a maintains the magnetic field and aids in dielectric strength recovery of the air gap, thereby increasing the dielectric strength of the air gap. to prevent re-ignition. When the arc reignites in the magnetic field, the magnetic field extinguishes the arc again. The device of the present invention is small enough to fit into existing circuits and disconnect panel boards, and also has an effective
It can repeatedly interrupt currents exceeding the effective value of 100,000 amperes. At such a current,
The arc that forms between contacts 153 and 155 when they open must be extinguished in about 1 millisecond or less. This is accomplished by the generation of a sustained arc voltage that reaches the magnitude of the applied supply voltage in about 1 millisecond or less. The structure used to achieve this result includes a quick-acting mechanism for opening blades 152 and 154 with contacts 153 and 155, and a magnetic core structure 1.
81, a coating of the arc chamber with arc quenching material, and a resistor 192 sustained in parallel with contacts 153 and 155. A magnetic core structure 181 surrounds contacts 153 and 155 and most of blades 152 and 154, is perpendicular to blades 152 and 154 and also perpendicular to the arc, and has a maximum actual value. gives a magnetic field with a magnetic flux density of The magnetic field exerts a force on each blade that "blows" them apart, and also forces it into the arc 208.
It gives a force that makes it ``blow away'' towards 2.
The force is proportional to the product of current and magnetic flux density. Since the magnetic flux density is derived from the current, the force is proportional to the square of the current; the greater the current, the faster the blade opens and the faster the arc is blown out. The response of the current limiter is thus proportional to the extent of the short circuit. Magnetic core structure 181 and blades 152 and 154 are arranged such that the lines of force of the magnetic field intersect blades 152 and 153 and current flows through the blades in a direction opposite to the direction of flow that causes the blades to separate. be done. Looking at Figure 1, the current is cable 15
1, through contacts 153 and 155, from the contact end of blade 154, back through blade 154, and then out through cable 178. The magnetic flux and lines of force in the magnetic field are the legs 183a of the magnetic core 183.
(Fig. 23) to the magnetic core 182 (Fig. 1 and 2).
3) toward the leg portion 182a. This arrangement of current passing through blades 152 and 154 and magnetic flux across the blades tends to separate blades 152 and 154. Furthermore, when blades 152 and 154 separate and arc 208 is formed between contacts 153 and 155, current flows through said arc to contact 153.
and flows to the contactor 155. The transverse magnetic field in which the lines of force extend from leg 183a to leg 182a and causes current to act on the arc, as described above, will therefore "blow" the arc forward, ie, toward arc plate 134. This "blowing" action effectively increases arc length, resistance, and therefore arc voltage, resulting in arc extinguishment and current limiting. The magnetic field is also the contact 15
This accelerates the rate of dielectric strength recovery of the air gap across 3 and 155, extinguishing the arc and resulting in a continuous increase in the voltage applied to the air gap after current transfer. More importantly, with increasing arc voltage, the transverse magnetic field increases the power factor of the circuit by inserting a resistor into the essentially inductive short circuit, thereby increasing the current relative to the voltage. This has the effect of reducing the delay. The power factor is increased to nearly unity. Blades 152 and 154 are elongated and pivoted about respective respective pins 166 and 167 to provide a leverage effect that increases velocity and resistance at each contact end when actuated by magnetic core 156.
Thus, when core 156 is biased to raise armature pin 161 a given distance within a predetermined time, each contact end of blades 152 and 154 and each contact 153 and 155 will correspond. armature pin 16
move a greater distance in a short time than a displacement and velocity ratio of 1. Contact blades 152 and 154 and contact 153
and 155 are shaped and dimensioned to provide a structure of fairly low mass and minimal inertia that responds rapidly and opens rapidly when the electromagnet is energized. The contact blades 152 and 154 have a current flow rate of 1/16th cycle, or about 0.001 seconds (1
It can be constructed and installed with dimensions that provide a gap on the order of 0.635 cm (1/4 inch.) within milliseconds. Electromagnetic means (magnetic core 156 and armature 15
8, pin 161 and connecting link), field magnet structure 181, blades 152 and 154, and the particular method of positioning and coupling them as described above.
Within approximately 0.0002 seconds (0.2 milliseconds) of the onset of fault current in the circuit within 1/80th of a cycle of current above the threshold selected for operation of the current limiter, i.e. 80 of 1 cycle of current. The current-limiting contacts 153 and 155 will be opened within 1/2. Under high short-circuit current conditions, the current-limiting contacts 153 and 155 are connected 0.2 milliseconds (1/80
cycle) is released in a shorter time. As the contacts open, an arc is formed between them.
Arcs between current limiting contacts are typically extinguished within one millisecond by the structure and mechanism of the present invention. It should be noted that the mechanism responds with the square of the magnitude of the fault current, such that the response of the current limit becomes faster as the fault current increases. This accelerating response is due not only to the speed of contact separation, but also to the lengthening of the arc due to rapid and large contact separation, all of which increase arc resistance and arc voltage;
The contactors 153 and 155 of the transverse magnetic field created by the field magnet structure 181 increases the arc voltage almost instantaneously (by forward bending and cooling) to equal the supply voltage. It also includes effective responsiveness to arcs formed during When the arc voltage equals the supply voltage, the current no longer continues to increase and is completely transferred into the current limiting resistor 192 where energy is dissipated. The main contacts 53 and 70 of the circuit breakers open within 0.004 seconds from the start of the fault current, i.e. within 1/4 cycle of a current of 60 cycles/second, and by then the fault current has been sufficiently drained by the current limiting resistor 192. divided into
There the energy is dissipated. Main contactor 53
and 70 open, the current will no longer flow into the protected circuit within 1/4 cycle or 4 milliseconds after the appearance of the fault current exceeding the threshold selected for the current-limiting part of the circuit breaker. It's summery. According to the invention disclosed herein, the effective current limiting response due to the combination of (1) the speed of contact separation and (2) the increase in arc voltage until it equals the supply voltage is approximately 1 mm. Occurs within seconds. This is important because the maximum increase in current per time occurs as soon as the current value reaches zero, ie the slope of the sinusoidal waveform of the current reaches its maximum just after the zero value of current. The current limiting means according to the present invention shunts the short circuit current to the current limiting resistor 192 having a positive temperature coefficient of resistance before the short circuit current increases rapidly following the current value of zero. The mechanism can be mounted in a compact case to fit into a standard panel board. This compactness is measured as the ratio of the short-circuit amperage rating to the volume of the circuit breaker. The following table provides a rational explanation of the volumetric efficiency of shorting and breaking of the subject circuit and disconnector. The volumes of five typical circuit breakers are shown in the second column, and the break ratings are shown in the third column. The circuit breakers and disconnectors in the first row of the following table are those that are the subject of the present invention.

[Table] Additional features of the present invention that help fit the height and disconnection mechanism into minimum volume circuits and disconnectors include current limiting contacts 153, 155 and blades 152,
The arc plate 134 is located in front of the arc plate 154. One of the current limiting characteristics of the present invention is to rapidly increase the arc voltage to equal the power supply voltage. However, when high arc energy is applied to the air space within the arc chamber, the air temperature rises very quickly creating shock waves and large pressure gradients that must be dissipated. Devices designed to limit current by producing high arc voltages were therefore too bulky. This had to include a large volume chamber to dissipate the shock waves and pressure gradients created by the current limiting means. The present invention couples the arc voltage increase to other current limiting means, so that the magnitude of shock waves and pressure gradients are much smaller than in systems relying solely on arc voltage means. Furthermore, the arc plate 134 is sized and shaped as described above with respect to the direction of the arc, its path of motion, the resulting shock wave and air pressure gradient;
and is mounted to interrupt and effectively dissipate such forces without the need for a significantly large volumetric chamber. The arc quenching material that coats the magnetic core structure 181 and aligns the inside of the rectangular tube formed thereby and the insides of the conductor turns 188d and 199a to a significant degree prevents contact during and immediately after the arc quenching operation. Determine the dielectric strength recovery speed between the two. Dielectric strength recovery is important for the current limiting process, which is further facilitated by the magnetic field. The arc quenching material is selected in accordance with the disclosure of the aforementioned US patent application Ser. No. 364,596. Resistor 192 has a positive direction that can change from a very low value to a very high value after the arc spanning contacts 153 and 155 is extinguished and all current is forced to flow through the resistor and bypass the contacts. It should have a resistance value that can be converted to . The change in resistance increases the power factor of the circuit, aids in shearing, and limits the current flowing through temperature control resistor 192. Various changes may be made to the structures shown and described herein without departing from the spirit of the invention or the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 shows a three-pole current-limiting circuit breaker constructed in accordance with the present invention cut along line 1-1 in FIG. 2 is a sectional view taken along line 2-2 in FIG. 1 of the current-limiting type circuit breaker in FIG. 1, FIG. 3, FIG. 4, FIG. 5, and 6 are an enlarged perspective view, a top view, a side view, and an outer end view, respectively, of a support assembly for any single pole line terminal and fixed contact of the current-limiting circuit breaker of FIG. 1; FIG. , FIG. 7 is an enlarged end view of a partially cutaway operating mechanism at the center pole of the current-limiting circuit breaker of FIG. 1 when the components are in the tripped position, and FIG. 8 is an enlarged end view of the operating mechanism of FIG. A partially cutaway side view of the mechanism, Figure 9 is an enlarged cross-sectional view of the blade between the two blades of the current-limiting circuit breaker in Figure 1, and Figure 10 is a similar figure to Figure 9 at the central pole blade. FIG. 11 is an enlarged longitudinal sectional view of the thermally actuated common trip rod of the current-limiting circuit breaker of FIG. 1, and shows the broken end of the associated thermal trip lever. Edge view, FIG. 12, is a full-scale cross-sectional view taken along line 12--12 of FIG. 11 of the thermally actuated common trip rod, and a side view of the associated thermal trip lever, FIGS. 13 and 14; , Figures 15 and 16
The figures show a perspective view, a left end view, a side view, and a right end view, respectively, of an assembly of electrical conductors associated with an electromagnet in the current limiting portion of any one pole of the current limiting circuit breaker of FIG. FIG. 14,
15 and 16, some parts are broken or omitted, and FIGS. 17, 18, and 19 respectively show any part of the current-limiting circuit or breaker shown in FIG. 1. 1 from Fig. 14 at the pole.
20 is a perspective view, a side view, and an end view of an electromagnet and its contact blade assembly associated with the conductor assembly of FIG. 6, partially cut away in FIGS. 18 and 19; Figure 21 is a plan view of an unfinished current limiting resistor for any one pole of the current limiting circuit breaker or disconnector of Figure 1, including the end portion to be cut off after electroplating; Figure 21 is Figure 20; FIG. 22 is a plan view of the end portion of the resistor within the area 21 surrounded by the dotted line, the dashed line portion indicating the portion to be removed after electroplating, and FIG. Figures 23, 24 and 25 are, respectively,
A perspective view, an end view, and a side view of the arbitrary one-pole field magnet assembly of the current-limiting type circuit breaker of FIG. 1, No. 26
27, 28, and 29 are a perspective view, a top view, and a top view, respectively, of an assembly of an arbitrary one-pole electric conductor and a load terminal of the current-limiting circuit breaker of FIG. Inner end view and side view, Figures 30 and 31
32 is a perspective view and a front view, respectively, of an arc chute adjacent to the load terminal assembly of any one pole of the current-limiting circuit breaker of FIG. 1, and FIG.
33 is a cross-sectional view taken along line 32--32 in
A perspective view of one of the arc plates in the arc chute in Figures 0 to 32; Figure 34 is taken along line 34-3 in Figure 2;
4 is a longitudinal cross-sectional view of the current-limiting circuit and disconnector of FIG. 1 along line 4, showing the outer pole when the component is in the ON position; FIG. 40...Three-pole current-limiting circuit breaker, 48...Line terminal and fixed contact assembly, 60...Connector body, 76, 106...Trip lever, 112...
... Armature plate, 113, 156 ... Magnetic core, 12
2... Barrier plate, 123... Latch plate, 134...
Arc plate, 145...Bimetal strip, 158...
... Armature, 180 ... Shock-absorbing material piece, 181 ...
...Magnetic core structure, 192...Resistor, 202...
...Arcshoot, 206... Ventilation board.

Claims (1)

[Claims] 1. A molded case 41, 42; a first pair of separable contacts 53, 70 within the case;
a thermally and electromagnetically operable trip means 76, 112, 113 within said casing which, when actuated, separates said first pair of contacts; a pair of elongated contacts pivotally mounted within said casing; blades 152, 154, each contact blade carrying a contact 153, 155 which, when the contact blade is in the closed position, overlaps the contact on the other contact blade. and the contact on the contact blade is engaged with the first
a pair of contact blades 152,1 such as a second pair of separable contacts connected in series with the pair of contact blades;
54; and electromagnetically operable means 156, 158, 161, 163, 164 within the case for separating the contact blade and the contact when actuated.
and; within the case, the second pair of contacts 15;
3,155 and a resistor 192 connected in parallel with the resistor 192, the resistor having a resistance that can vary from a relatively low value to a relatively high value depending on temperature changes; an elongated magnetic structure 181 spanning either side of the contact blade along a substantial current carrying portion comprising portions of the electromagnetically operable means 156, 15;
8, 161, 163, 164 in a direction transverse to the separation direction of the contacts and transverse to the arc formed between them upon separation of said contacts, and said contact blades 152, 1
a magnetic structure for establishing a magnetic field transverse to the direction of current flow at 54; said contact blade 15;
2, 154 and the magnetic structure 181 so that they cooperate and simultaneously push apart the contact blades in response to a fault current, causing the arc to move away from the contact. Means 1
88,199, current-limiting type circuit breaker. 2. In the current-limiting type circuit breaker according to claim 1, the resistor 192 is made of a material having a positive temperature coefficient, and the circuit of the circuit breaker is connected to the first pair. a first connection between the separable contacts 53, 70 and the second pair of separable contacts 153, 155 and the second pair of contacts 15;
3,155, said interconnection means including one of said pair of elongated contact blades 152 and a magnetizing conductor turn 188; The blade is connected at one end region to a conductor reaching the first connection and conductive at the other end region via the second pair of contacts 153, 155 to the other 154 of the pair of elongated contact blades. The magnetizing conductor turning portion has one end connected to the conductor reaching the first connection portion, and the other end connected to the conductor reaching the second connection portion. and each of said one elongated contact blade 152 and said magnetizing conductor turns are arranged between opposite sides of said elongated magnetic structure for a substantial current-carrying portion of their respective lengths. A current-limiting type circuit breaker characterized by being arranged so as to extend in the same direction from one end. 3. The current-limiting circuit breaker according to claim 1, which includes a conductor turning section 188 for the magnetic structure 181, and this conductor turning section is connected to the first pair of contacts 53, 70 and the resistor 192, the conductor turning portion and the resistor 19
2, the second pair of contacts 153,1
54 in parallel.