JP4893450B2 - Circuit breaker and SPD protection system using the circuit breaker - Google Patents

Description

The present invention, SPD (S urge P rotective D evice, surge protection device) circuit breaker to be installed to arranged the circuit, and to a SPD protection system using the circuit breaker.

  In recent years, there has been a tendency for the occurrence of torrential rains and lightning, which are thought to be the effects of global warming, and on the other hand, the damage to various load devices due to lightning surges due to the spread of electronic devices due to the advancement of advanced information society. I do not hesitate to say that is increasing. Therefore, in order to protect the load device from the lightning surge, it is known to arrange an SPD such as an arrester or a varistor between the input side of the load device and the ground (ground) (for example, Patent Document 1). reference).

  By the way, this SPD can also be regarded as one “device” on the electric circuit, and as the SPD becomes widespread, its overcurrent protection has recently begun to be highlighted. Against this background, the installation of overcurrent protection devices responsible for SPD short-circuit protection has been standardized (for details, refer to JIS (Japanese Industrial Standards) C-60364-5-53 (Building Electrical Equipment-Part 5-53). In response to this, the number of cases in which circuit breakers are installed above SPDs is increasing (for example, patent literature). 2 or 3).

  On the other hand, as disclosed in Patent Document 1, when a lightning surge is discharged to the ground through the SPD, a discharge current having a long duration is generated, but when a circuit breaker is installed above the SPD, Naturally, the discharge current continues to flow through this circuit breaker. For this reason, the discharge current causes the movable contact to rise from the fixed contact of the circuit breaker, and an arc is generated between the two contacts (this is generally referred to as arcing). There is concern about the occurrence of welding. Therefore, the alarm and auxiliary switch provided in the circuit breaker are devised for the interlocking timing of the circuit breaker mechanism, and an output is obtained from the alarm switch, but no output is obtained from the auxiliary switch. In addition, it is disclosed to notify a situation of occurrence of welding of the circuit breaker (see, for example, Patent Document 4).

Japanese Unexamined Patent Publication No. 2000-166079 (page 3, left column, 8th to 11th lines, FIG. 1) JP 2002-101505 A (page 4, left column, lines 10-12), FIG. 1) JP-A-2005-237157 (page 4, line 20 to line 30, FIG. 1) JP 11-67048 A (page 5, left column, lines 1 to 32, FIG. 1)

  It is well known that various countermeasures and measures have been devised from each manufacturer, including Patent Document 4, for the welding of the circuit breaker. Subsequent countermeasures for occurrence of welding (including the realization of the so-called isolation function that prevents the tilting handle of the circuit breaker from displaying the OFF position at the time of welding), or canceling it by operating the tilting handle (welding separation) ). Therefore, when protecting the SPD, when considering the installation location of the SPD, these countermeasures have their own limits. That is, the SPD is installed in a wide range. For example, in an unmanned repeater station at the top of a mountain, it is difficult to say that the operation of the above-described tilting handle is a realistic response. Even if it is enriched, economic losses related to maintenance such as replacement of circuit breakers cannot be ignored. That is, the circuit breaker that protects the SPD is required to prevent welding due to arcing.

In pursuing experiments and evaluations to achieve this prevention of welding, the inventors discovered the contents described below. In other words, in the process leading to welding, the current tripping element of the circuit breaker was supposed to operate in response to an excessive load current. This means that there is a region where the current tripping element does not respond due to the short duration. In general, since the operation of the current tripping element of a circuit breaker takes several milliseconds, especially in the case of a circuit breaker intended to limit the current at the time of a short circuit, Therefore, the operation of the current tripping element is not waited using the electromagnetic repulsive force generated between the fixed contact provided with the fixed contact and the movable contact provided with the movable contact. In addition, it is known that a movable contact is lifted from a fixed contact to open a high speed. On the other hand, in the circuit breaker having this current limiting structure, under the use conditions in the commercial frequency component,
Current value at which the movable contact rises (A)> Current value at which the current tripping element operates (B)
However, it is needless to say that the current tripping element always reacts with a large current that generates an electromagnetic repulsive force.

However, in the case of a short time width such as lightning surge current, as described above,
Current value at which the movable contact floats (A) <Current value at which the current tripping element operates (B)
It has been found that the reverse phenomenon occurs, and the reclosing due to the fact that the current tripping element does not respond has increased the possibility of welding between the two contacts through the arcing due to the floating. Here, the problem is that the current tripping element does not respond. As represented by Patent Document 4, as long as the welding is reported based on this response, it is used for SPD protection. I have to say that is not suitable. In other words, continuation of use without recognition of welding leads to loss of the original function of the circuit breaker, such as short circuit between the circuit breaker and the earth or interruption due to ground fault, as well as protection of the SPD. There was a risk of spilling over serious accidents such as electric shocks.

  The present invention has been made to solve the above-described problems. A circuit breaker that does not cause welding even when a lightning surge enters is obtained, and an SPD protection system using the circuit breaker is provided. In particular, it is intended to be provided to SPD users.

  A circuit breaker according to the present invention includes a housing, opening / closing means for opening and closing a current flowing in the electric circuit that is housed in the housing, and a current tripping element that responds when the current is a surge current generated by a lightning strike, etc. A toggle link mechanism for operating the switching means based on the operation of the current tripping element to open the circuit, and when the surge current passes through the circuit breaker, the switching current is generated by the surge current. Before the arc between the fixed contact and the movable contact that constitutes, the current tripping element is operated to open the circuit.

  In addition, the SPD protection system according to the present invention includes the circuit breaker described above on the upper side of the SPD disposed between the input side of the load device connected to the bus and the ground, and in the electric circuit branched from the bus. Is installed.

  As described above, since the circuit breaker can be applied as an SPD overcurrent protection device as described above, the reliability of the SPD protection system can be improved and the system with excellent cost performance can be constructed.

Embodiment 1 FIG.
1 is a cross-sectional view of a circuit breaker according to Embodiment 1 of the present invention, FIG. 2 is a configuration diagram of an SPD protection system using this circuit breaker, and FIGS. 3 and 4 show the lightning surge current in FIG. FIG. 3 shows a reclosing and FIG. 4 shows a trip, respectively. FIG. 5 is a graph showing the test results with the current waveforms in FIGS. 3 and 4.

  In FIG. 1, a circuit breaker 101 includes a breaker mechanism 51 in a casing constituted by a cover 1 and a base 2, and this breaker mechanism 51 is an opening / closing means for opening and closing a load current flowing in an electric circuit (not shown). A certain repulsive contact 3 and a movable contact 4 that contacts and separates from the repulsive contact 3, a toggle link mechanism 52 that separates the movable contact 4 from the repulsive contact 3 when an overcurrent flows, an electromagnetic trip mechanism And a current tripping element 53 having a thermal tripping mechanism and an arc extinguishing plate 5.

  The repulsive contact 3 is provided with a repulsive contact 3a, and the movable contact 4 is provided with a movable contact 4a facing each other. An arc extinguishing plate 5 is disposed in the vicinity of the repulsive contact 3a and the movable contact 4a. Yes. Reference numeral 6 denotes an arm made of an insulating material, and the movable contact 4 is held by the arm 6 so as to rotate together with the arm 6 about a shaft 7.

  Reference numeral 8 denotes a pin pivotally attached to the arm, and the lower end portion of the lower link 9 constituting a part of the toggle link mechanism 52 is coupled to the pin 8. The upper end of the lower link 9 is coupled to the lower end of the upper link 11 by a pin 10, and the upper end of the upper link 11 is coupled to the cradle 13 by a pin 12. The cradle 13 is pivotally supported by a shaft 14 and has a locking portion 13a at a free end. Reference numeral 15 denotes a spring stretched between the raising / lowering handle 16 and the pin 10.

  The current tripping element 53 includes a current relay 17, a bimetal 18, a trip bar 19, a latch 20, a locking lever 21, and the like. Reference numeral 22 denotes a power supply side terminal connected to the power supply side of the electric circuit, 23 denotes a shunt that electrically connects the power supply side terminal 22 and the repulsive contact 3, and 24 denotes a load side of the electric circuit (that is, an SPD side described later) ) Is connected to the load side terminal. In this embodiment, the current limiting structure, that is, the repulsive contact 3 intended for high-speed opening is used, but it is not always necessary to have this current limiting structure, and the movable contact 4a and The opposing contact may be a fixed contact provided on a fixed contact that extends from the power supply side terminal 22 and is directly fixed to the base 2.

  Next, the operation of the circuit breaker 101 will be described in connection with the SPD 102 shown in FIG. By operating the tilting handle 16 in the clockwise direction on the paper surface, the upper link 11 and the lower link 9 are extended as shown in FIG. 1, and the arm 6 gives a clockwise turning force about the shaft 7. As a result, the movable contact 4a comes into contact with the repulsive contact 3a. At this time, since the locking portion 13a of the cradle 13 is locked to the locking lever 21, the extended state of the upper link 11 and the lower link 9 is maintained, and the contact between the repulsive contact 3a and the movable contact 4a is maintained. As a result, the circuit breaker 101 is turned on. Accordingly, when the circuit breaker 101 is turned on, the SPD 102 shown in FIG. 2 is disposed between the bus 98 and the ground 99, and direct lightning or induced lightning entering the bus 98 is caused to pass through the SPD 102. By escaping to the ground 99, the load device 100 connected to the bus 98 is protected from lightning surge.

  In particular, when a direct lightning strike enters, the flow returns to FIG. 1 again, the current relay 17 is activated, the trip bar 19 is rotated clockwise about the shaft 19a, and the latch 20 is counterclockwise about the shaft 20a. Turn to. By the rotation of the latch 20, the engagement with the locking lever 21 is released, and the locking lever 21 is rotated counterclockwise about the shaft 21 a by the biasing force of a spring (not shown) to engage the cradle 13. The stop 13a is disengaged from the locking lever 21. Then, the upper link 11 and the lower link 9 are buckled, and the arm 6 receives a counterclockwise turning force about the shaft 7, so that the movable contact 4a starts to be separated from the repulsive contact 3a. In addition, before this separation, the repulsive contact 3 and the movable contact 4 are separated from each other due to the electromagnetic repulsive force caused by the opposite directions of the current flowing through the repulsive contact 3 and the movable contact 4. That is, the repulsive contact 3 operates in the clockwise direction around the shaft 3b, and the movable contact 4 operates in the counterclockwise direction around the shaft 7 as the rotation center. At this time, the arc generated between the two contacts is quickly extinguished by the arc extinguishing plate 5, and the interruption, so-called trip operation is completed.

  As described above, as is apparent from the above description, even though the “circuit breaker for SPD protection” is not added, any workmanship or members are not added for this purpose. Intended for use with circuit breakers. However, even in the case of a general-purpose circuit breaker, when the direct lightning strikes, the two contacts are disconnected without welding the two contacts, in other words, the current for operating the current relay 17 How the value was derived will be described in detail below.

First, the waveform of the lightning surge current related to the SPD is JIS C-5381-1 (required performance and test method of the surge protection device connected to the low-voltage power distribution system) and this explanation, according to the SPD installation purpose. This SPD is classified as class I (assuming direct lightning strike) and class II (assuming induced lightning), and is defined as follows.
Class I wavefront length: 10 microseconds, wavetail length: 350 microseconds Class II wavefront length: 8 microseconds, wavetail length: 20 microseconds, so here the conditions are more severe (even if the peak value is the same, the waveform When compared, Class I was intended to protect SPD applied to Class I (which has an energy I ² t about 30 times that of Class II). In addition, two general-purpose models shown below were selected as circuit breakers.
Sample 1: 250 AF, rated current 225 A, instantaneous trip current value 3150 A
Sample 2: 400AF, rated current 400A, instantaneous trip current value 4000A
(AF: Ampere frame)
Furthermore, in confirming the presence or absence of welding and tripping, the installation location of the load current superimposed on the above-described lightning surge current (that is, the circuit breakers (samples 1 and 2)) is as shown in FIG. did).

  The experimental results under the conditions described above are shown in FIGS. First, in FIG. 3, after a lightning surge current flows (b), a period in which the load current does not flow temporarily occurs (b), and thereafter the load current flows again (c). That is, although the movable contact 4a is lifted by the lightning surge current (b), the current tripping element 53 does not operate and the contacts are reclosed (c). Therefore, there is a very high possibility that arcing due to floating and welding due to reclosing have occurred (the result of this experiment is the basis for the contents described in “Problems to be Solved by the Invention” 0008). On the other hand, in FIG. 4, after the lightning surge current flows (b), no load current flows (b), that is, no reclosing occurs. Therefore, it can be seen that after the movable contact 4a is lifted, the current tripping element 53 is actuated to mechanically open the movable contact 4.

The results of these two experiments, that is, contact lift (FIG. 3) and instantaneous operation (FIG. 4) were performed on the two models described above, and the minimum peak values of each were plotted on a so-called circuit breaker characteristic graph. This is shown in FIG. As can be seen from this figure, the contact floating current value during lightning surge current passage is
Sample 1: 8 kA (peak value)
Sample 2: 14 kA (peak value)
On the other hand, the instantaneous tripping current value during lightning surge current passage is
Sample 1: 25 kA (peak value)
Sample 2: 28 kA (peak value)
Met. From this result, the inventors found the following description. That is, in tripping with commercial frequency components and tripping with lightning surge current,
Sample 1: 25 kA / 4450 A≈5.62 (4450 A is converted into a peak value)
Sample 2: 28 kA / 5660A≈4.95 (5660A is converted into a peak value)
That is, there is an opening of about 5 times.

The inventors paid much attention to this “5 times” result. In other words, the relationship described in "Problem to be solved by the invention" 0008 is returned to the relationship described in 0007, and in a more understandable manner,
With lightning surge current Current value when movable contact rises with lightning surge current (C)> Current value with which current tripping element operates (D)
In order to achieve this, the instantaneous tripping current value in the commercial frequency component may be obtained by dividing the above-described current value at the time when the contact is lifted by five. When this is specifically quantified,
Sample 1: 8 kA / 5 = 1.6 kA (effective value conversion: 1.1 kA)
Sample 2: 14 kA / 5 = 2.8 kA (effective value conversion: 2.0 kA)
Furthermore, this value is
Sample 1: 1.1 kA / 225 A≈4.89
Sample 2: 2.0 kA / 400 A = 5
Therefore, if the instantaneous tripping current value is set to 5 times the rated current, it can be expected to prevent welding between the two contacts when the lightning surge current passes.

More realistically, considering the margin, it is preferable to set it to 4 times the rated current or less. In other words, the instantaneous tripping current value of a general-purpose circuit breaker is
Sample 1: 14 times (3150A / 225A)
Sample 2: 10 times (4000A / 400A)
On the other hand, the current relay 17 can be made to function as an “SPD protection circuit breaker” simply by reviewing and changing the spring constant, for example, to 4 times or less.

  Here, decreasing the instantaneous tripping current value tends to cause an unnecessary (trip) operation, and thus generally tends not to be preferred. However, this SPD protection is shown in FIG. As described above, since the circuit breaker is installed exclusively for SPD (corresponding to FIG. 53A of the above-mentioned JIS C-60364-5-53), the load current does not flow at all times. do not have to. Needless to say, even if the "trip operation for preventing welding", which is the essence of the present invention, is performed, it should be a direct lightning strike (10/350 microseconds) before both contacts are opened. However, in the case of induced lightning (8/20 microseconds), these lightning surge currents are discharged to the ground without any problem through the SPD, so that they do not interfere with the lightning surge protection for the load equipment.

  As described above, since the load current was superimposed in the experiment, the location of the circuit breaker was set as (b) in FIG. 2, but this installation (JIS C-60364-) was performed in an actual SPD protection system. 5-3 (corresponding to Fig. 53B), if the SPD should fail, such as an internal short circuit, the circuit breaker trips, and the load equipment is not supplied with power until the SPD is replaced. In other words, although the purpose of use is always to give priority to lightning surge protection for the load equipment, there is a possibility of unnecessary operation at the start inrush current of the load equipment, for example, due to the reduction of the instantaneous trip current value Becomes extremely high. Therefore, for example, if another general-purpose circuit breaker is installed in (c) in FIG. 2 and the SPD protection circuit breaker (a) trips, an interlock is built so that the circuit breaker in (c) also trips. If this is the case, it is preferable because both the continuation of power supply and lightning surge protection can be achieved. In any case, it is better to use this SPD protection circuit breaker exclusively for “SPD” in view of reducing the instantaneous tripping current value.

  As described above, since it is possible to provide an inexpensive circuit breaker for SPD protection only by reducing the instantaneous tripping current value of the general-purpose circuit breaker, the cost effectiveness of the SPD protection system is improved. Moreover, since this circuit breaker can be prevented from being welded, the reliability of the SPD protection system can be improved. When considering the premise of tripping to prevent welding, an alarm switch is built in the circuit breaker, and this output contact is used to recognize trip (passing lightning surge current). It is preferable to perform re-input work based on this recognition. If it is difficult to respond to trips such as the above-mentioned unmanned relay station at the top of the mountain, for example, an electric operation device is installed in the circuit breaker, and the DC power source using the storage battery including the output contact described above is used again. A possible control circuit may be configured. Furthermore, the response of the alarm switch represents the above-described lightning surge current passing, that is, the processing in the SPD of the lightning surge current exceeding the contact lift. For example, if this response is counted, the frequency of use of the SPD You can also expect side effects such as

The method of selecting the tripping current value, which is the essence of the present invention, is as described above. However, the “instantaneous tripping current value during lightning surge current passage”, which is one guideline for this selection, is based on experiments. For example, it may be derived by estimating from the allowable I ² t of the circuit breaker. That is, as shown in FIG. 5, it is an operating point in the commercial frequency component of each sample.
Sample 1: Blocking 4000 A in 20 milliseconds Sample 2: Blocking 3150 A in 20 milliseconds, calculating allowable I ² t (sample 1- (I), sample 2- (B)), crossing in 350 microseconds This is the idea that the current value at this point is. Since 25 kA (sample 1) and 28 kA (sample 2) that have actually been pulled out are close to their respective allowable I ² t, it is also effective in determining a rough standard.

It is sectional drawing of the circuit breaker in Embodiment 1 of this invention. It is a block diagram of the SPD protection system in Embodiment 1 of this invention. FIG. 3 is a current waveform diagram when a lightning surge current is injected into an SPD in FIG. 2. FIG. 3 is a current waveform diagram when a lightning surge current is injected into an SPD in FIG. 2. It is a graph which shows a test result.

Explanation of symbols

1 cover, 2 base, 3a repulsive contact, 4a movable contact, 17 current relay,
51 interruption mechanism, 52 toggle link mechanism, 53 current tripping element, 98 bus,
99 ground, 100 load equipment, 101 circuit breaker, 102 SPD.

Claims (3)

A case, an opening / closing means for opening and closing the current flowing in the electric circuit that is housed in the case, a current tripping element that responds to a surge current generated by a lightning strike, and the operation of the current tripping element. In a circuit breaker provided with a toggle link mechanism for operating the switching means to open the electric circuit based on
When the surge current passes through the circuit breaker, the current trip element is operated before the surge current ignites between the fixed contact and the movable contact constituting the switching means. A circuit breaker configured to open the circuit. An SPD comprising: the circuit breaker according to claim 1 disposed above an SPD disposed between an input side of a load device connected to the busbar and the ground, and in an electric circuit branched from the busbar. Protection system. 3. The SPD protection system according to claim 2, wherein the surge injected into the SPD has a wavefront length of 10 microseconds and a wavetail length of 350 microseconds.

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