JP4262842B2 - Overcurrent indicator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is used by suspending directly on a high-voltage distribution line or a low-voltage distribution line in order to quickly find the point of an accident. The present invention relates to an improvement of an overcurrent passing display device in which the display is restored after a predetermined time has elapsed.
[0002]
[Prior art]
Conventionally, it is used by suspending directly on electric wires such as high-voltage distribution lines (hereinafter simply referred to as electric wires), and when an overcurrent flows through the electric wires, it is detected and an accident occurrence is indicated, and after a certain period of time has passed. There has already been proposed an overcurrent indicator for returning the display.
[0003]
The above-described conventional overcurrent indicator includes a current detection unit that detects a current flowing through the electric wire, a comparison unit that compares the detected current value with a preset current value, and an output of the comparison unit. And a display unit that resets the display by an output of a time counter described later, a time counter that measures a certain time, and a power supply unit that supplies power to each of the above units. Since the detected current does not exceed the set value V during normal operation, no output is output from the comparison unit and no overcurrent display is performed. When an overcurrent occurs, the magnitude of the current detected by the current detection unit exceeds the set value, so an output is made on the display unit and an overcurrent display is made. From this time, the time counting unit starts counting, and after a certain time (for example, 5 hours) has elapsed, a return signal is output to the display unit to reset the display.
[0004]
[Problems to be solved by the invention]
2. Description of the Related Art In recent years, household appliances and OA devices that are widely used have built-in rectifiers and inverters using semiconductors, and most of these devices are sources of harmonic current. Harmonics generated from the equipment may enter the distribution line, distort the current waveform flowing through the distribution line, and sometimes become a large current. In this case, there has been a problem of erroneous display that the overcurrent indicator judges that it is an overcurrent and displays an overcurrent. Harmonic surge current due is independent of the accident distribution line be those of instantaneous overcurrent indicator that can eliminate such erroneous display is desired.
[0005]
[Means for Solving the Problems]
Therefore, the present invention detects the current (I) flowing in the electric wire (2) such as a high-voltage distribution line in order to prevent the overcurrent from being easily displayed even if a harmonic or surge enters, and a detection signal When the current detection unit (17) that outputs (D), the signal processing unit (14) that detects overcurrent based on the detection signal (D), and the signal processing unit (14) detects overcurrent An overcurrent indicator having a display section (5) for displaying overcurrent,
The signal processing unit (14) includes a comparison unit (18) that outputs an output when the level of the detection signal (D) exceeds a preset level, and a delay from the output from the comparison unit (18). A delay unit (19) for outputting a square wave pulse having a constant time width (T2), and an AND circuit (20) for calculating a logical product of the output of the comparison unit (18) and the output of the delay unit (19), and an overcurrent display rows that are in the circuit (20) display unit in accordance with the output of the (5),
The delay unit (19) includes a first waveform generation unit (21) and a second waveform generation unit (22) that generate square wave pulses S1 and S2 having different time widths, respectively.
When the output of the comparison unit (18) is input to the first waveform generation unit (21), the first waveform generation unit (21) is triggered by the falling edge of the output to generate one square wave pulse S1 having a predetermined time width (T1). A one-shot multivibrator that does not output a new square wave pulse S1 even if there is an input from the comparator (18) during the output of the square wave pulse S1, and further, the fixed time width (T1) is It is set to a value between the length of half cycle to one cycle of commercial frequency power supply,
The second waveform generator (22) is triggered by the falling of the square wave pulse S1 output from the first waveform generator (21), and is one square wave having a certain time width (T2). Retriggerable one-shot multivibrator that outputs a pulse S2 and outputs a new square wave pulse S2 each time there is an input from the first waveform generator (21) during the output of the square wave pulse S2. Further, the constant time width (T2) is set to a value longer than one cycle (T) of the commercial frequency power supply, and an overcurrent indicator is provided.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
Next, a preferred embodiment of the present invention will be described with reference to FIGS.
Reference numeral 1 denotes an overcurrent indicator, an electric wire attachment portion 3 for attaching the indicator to a high voltage distribution line (hereinafter referred to as an electric wire) 2, a main body case 4 for housing the current detection portion 17 and the circuit board 12, and an overcurrent indicator. A display unit 5 and the like for displaying when a current is detected are provided.
[0007]
The main body case 4 is formed of a synthetic resin having excellent weather resistance, such as polycarbonate resin, and a lower part that forms a square core (iron core) 7 surrounding the electric wire 2 by contacting the upper core 6 inside thereof. The core case 10 assembled with the core 8 and the winding 9 wound around the lower core 8 is connected to the upper portion 6 of the lower core 8 from the through hole 4a provided on the upper surface of the main body case 4 with the joint 8a. It is housed inside the main body case 4 so as to protrude slightly toward the rear, and is screwed on. A gap between the through-hole 4a and the lower core 8 is filled with a sealing material 11 for preventing intrusion of rainwater or the like into the main body case 4.
[0008]
A circuit board 12 is screwed to the lower surface of the core case 10, and a rectifying unit 13, a signal processing unit 14, a timing unit 15, and a power supply unit 16 are mounted on the substrate 12.
[0009]
The rectification unit 13 performs full-wave rectification on the voltage induced in the winding 9 and outputs a detection signal D corresponding to the load current I of the electric wire 2 to the signal processing unit 14. The winding 9 constitutes a current detection unit 17.
[0010]
A signal processing unit 14 detects an overcurrent based on the detection signal D output from the current detection unit 17 and outputs a display signal P to the display unit 5 and the time measuring unit 15 when an overcurrent is detected. The comparison unit 18, the delay unit 19, and the AND circuit 20 are included.
[0011]
The comparison unit 18 receives the detection signal D output from the current detection unit 17, compares the set value V preset by the comparison unit 18 with the detection signal D, and the detection signal D exceeds the set value V. When an overcurrent flows through the electric wire 2, an output is output and input to the delay unit 19.
[0012]
The delay unit 19 includes a first waveform generation unit 21 and a second waveform generation unit 22 that generate square wave pulses S1 and S2 having different time widths. The first waveform generation unit 21 outputs the output of the comparison unit 18. Is input, a single square wave pulse S1 having a predetermined time width T1 is output when triggered by the fall of the output.
[0013]
The first waveform generator 21 uses a well-known one-shot multivibrator that does not output a new square wave pulse S1 even if there is an input from the comparator 18 during the output of the square wave pulse S1. The fixed time width T1 is set to a value between the half cycle and the length of one cycle of the commercial frequency power supply, and the fixed time width T1 sets a time for delaying the overcurrent display. The fixed time width T1 is different between the case of 50 Hz and the case of 60 Hz, and the time width can be switched by a switch not shown.
[0014]
The second waveform generator 22 is triggered by the falling edge of the square wave pulse S1 output from the first waveform generator 21, and outputs one square wave pulse S2 having a predetermined time width T2. In addition, the second waveform generator 22 outputs a new square wave pulse S2 each time a square wave pulse S2 is output from the first waveform generator 21. A one-shot multivibrator is used. The fixed time width T2 is set to a value longer than one cycle T of the commercial frequency power supply. This fixed time width T2 is different between the case of 50 Hz and the case of 60 Hz, and the time width is switched by a switch (not shown) so that it can correspond to the commercial frequency similarly to the time width T1.
[0015]
An AND circuit 20 outputs a display signal P to the display unit 5 and the time measuring unit 15 when both the output of the comparison unit 18 and the output of the delay unit 19 (square wave pulse S2 of the second waveform generation unit 22) are present.
[0016]
Reference numeral 15 denotes a time measuring unit which counts the clock from the crystal oscillating unit 23 that always outputs a clock and the clock from the oscillating unit 23 and outputs a return pulse when counted for a certain time (for example, 5 hours). 14 is provided with a time measuring unit 24 for resetting the count (time) when the display signal P is input from 14 and re-counting. Further, in order to drive the drive unit 28 of the display unit 5, the output of the oscillation unit 23 is output. A power storage unit 25 that boosts the voltage and charges the capacitor C1 is provided.
[0017]
Reference numeral 16 denotes a power supply unit which includes a rectifier R, capacitors C2 and C3, and a voltage stabilization unit 26, and rectifies and smoothes a voltage induced in the winding 9 wound around the lower core 8 by a current I flowing through the electric wire 2. Thus, the power is converted to a constant voltage and power is supplied to each of the parts 18, 20, 21, 22, 23, 24.
[0018]
A display unit 5 is provided on the lower surface of the main body case 4 and is electrically connected to the signal processing unit 14. The display unit 5 includes a display plate 27 that is rotationally driven, a drive unit 28 that electromagnetically drives the display plate 27, and a display cover 29 provided with a display window 29a. When the display signal P is output from the signal processing unit 14, the transistor Tr1 is turned on, the charge stored in the capacitor C1 flows into the display coil 28a, and the display plate 27 is driven to rotate 90 degrees. The colored portion 27a of the display board 27 can be seen from 29a, and overcurrent display is performed. Further, when a return signal (not shown) is output from the timer unit 15, the transistor Tr2 is turned on, and the charge stored in the capacitor C1 flows to the return coil 28b, so that the display board 27 is in an overcurrent display state. , The colored portion 27a of the display plate 27 is hidden on the display cover 29 and the display is restored.
[0019]
Reference numeral 3 denotes an electric wire mounting portion for suspending the main body case 4 from the electric wire 2. The mounting bracket 31 is attached to the main body case 4, and the mounting bracket 31 is connected to the hinge portion 30 a of the supporting bracket 30 and can be opened and closed. And a support bolt 32 for tightening the mounting bracket 31 and a nut 37 with a washer.
[0020]
The support metal fitting 30 is attached by connecting two support metal fittings 30 with rivets so that the support metal fitting 30 is fitted to a recess 4b provided on the upper peripheral surface of the main body case 4 via a buffer member 33. In addition, the support fitting 30 is provided with a wire receiving portion 30b formed by bending on the upper surface side of the main body case 4 that receives the electric wire 2 when the overcurrent indicator 1 is suspended from the electric wire 2, Is provided with a hinge portion 30'a that is connected to the mounting bracket 31 and the support bolt 32 and attaches the mounting bracket 31 and the bolt 32 so as to be freely opened and closed.
[0021]
Reference numeral 31 denotes a mounting bracket that is attached to one hinge portion 30a of the support fitting 30 so as to be freely opened and closed. The fitting 31 is formed in a substantially U-shaped cross section, and one end is attached to the hinge portion 30a so as to be opened and closed. The other end is provided with a notch 31a into which the support bolt 32 is inserted and a claw 31b that prevents the washer-attached nut 37 from being easily removed.
[0022]
Further, an electric wire support portion 31c formed by bending a part of the side surface to the side is provided at the center of the side surface of the mounting bracket 31, and the electric wire formed in a concave shape with an elastic member such as rubber in the portion 31c. When the holding member 34 is screwed and the overcurrent indicator 1 is attached to the electric wire 2, the electric wire 2 is clamped between the electric wire support portion 31c and the electric wire holding member 34 and the electric wire receiving portion 30b. ing. When the diameter of the suspended electric wire 2 is small, the attachment 40 is attached to the electric wire receiving portion 30b as shown in FIG. 1, and the electric wire 2 is clamped and fixed.
[0023]
Further, the upper core 6 is attached to the inside of the mounting bracket 31 so as to straddle the wire holding member 34, and the joint portion 6a of the upper core 6 that contacts the joint portion 8a of the lower core 8 is formed downward. Has been. Further, a leaf spring 35 is inserted between the upper surface side of the upper core 6 and the inside of the mounting bracket 31 so as to always press the upper core 6 downward.
[0024]
Note that a guide member 36 for closely guiding the joint 6a of the upper core 6 to the joint 8a of the lower core 8 when in contact with the joint 8a of the lower core 8 is closely attached to the joint 6a of the upper core 6. ing.
[0025]
Reference numeral 32 denotes a support bolt attached to the hinge part 30 ′ a of the support metal 30, which is fixed to the attachment metal 31 by being guided by the notch 31 a of the attachment metal 31 and tightening the nut 37 with a washer. The support bolt 32 is prevented from falling excessively into the inner side (side where the joint 8a of the lower core 8 slightly protrudes) by a stopper 4c provided on the upper surface of the main body case 4. Damage to the joint 8a is prevented.
[0026]
Reference numeral 38 denotes a sensor coil, which is provided for current detection when the rated current flowing through the electric wire 2 is large, for example, at 600A. Switching to the sensor coil 38 is performed by switching the switch 39 from the position shown in FIG. 1 to the sensor coil 38 side, so that the overcurrent can be accurately detected even if the rated current increases. Incidentally, the winding 9 is used for overcurrent detection and power supply to the power supply unit 16 when the rated current flowing through the electric wire is 300A.
[0027]
Here, the case where the overcurrent indicator 1 of the present invention described above is suspended from the electric wire 2 will be described. First, as shown in FIG. 5, the nut 37 with a washer of the wire mounting portion 3 provided on the upper portion of the overcurrent indicator 1 is loosened, the support bolt 32 is tilted to the outside of the main body case 4, and the mounting bracket 31 is turned counterclockwise. Rotate to open. The main body case 4 is moved upward from the lower side of the electric wire 2 as indicated by an arrow B in the above state so that the electric wire 2 is brought into contact with the electric wire receiving portion 30b of the support fitting 30, and the opened attachment fitting 31 is closed. Then, the support bolt 32 is raised, fitted into the notch 31a of the mounting bracket 31, and the nut 37 with washer is tightened to complete the operation of suspending the overcurrent indicator 1 from the electric wire 2.
[0028]
At this time, when the diameter of the electric wire 2 is small, the attachment 40 is attached to the electric wire receiving portion 30b, the electric wire 2 is brought into contact therewith, and the attachment fitting 31 is closed (FIG. 1). Further, the joint 6a of the upper core 6 provided on the inner surface side of the mounting bracket 31 is guided to the joint 8a of the lower core 8 by the guide member 36 attached to the portion 6a when the mounting bracket 31 is closed, and can be brought into close contact. It is like that.
[0029]
Next, the operation of the overcurrent indicator 1 of the present invention will be described based on the timing charts of FIGS. 6 to 8, I is the load current I flowing through the electric wire 2, (1) is the output of the current detector 17 (detection signal D), (2) is the output from the comparator 18, and (3) ▼ is the output of the first waveform generator 21 (square wave pulse S1), ④ is the output of the second waveform generator 22 (square wave pulse S2), and ▲ 5 is the output of the AND circuit 20 ( The display signal P) is shown.
[0030]
As shown in FIG. 6, the overcurrent indicator 1 detects the load current I flowing in the electric wire 2 that suspends the indicator 1 by the current detector 17 and induces it in the winding 9 according to the current I. The detected signal D is input to the signal processing unit 14 after full-wave rectification of the voltage. At this time, the comparison unit 18 of the signal processing unit 14 compares the detection signal D with a preset set value V. However, the detection signal D does not exceed the set value V, so that no output is performed. Therefore, the display signal P is not output from the signal processing unit 14, and the display unit 5 does not perform overcurrent display.
[0031]
Next, the case where an instantaneous overcurrent (for one cycle) occurs in the electric wire 2 due to a harmonic or the like as shown in FIG. 7 will be described.
The load current I flowing in the electric wire 2 from which the display 1 is suspended is detected by the current detection unit 17, the voltage induced in the winding 9 is rectified according to the current I, and the detection signal D is output to the signal processing unit 14. Then, the comparison unit 18 of the signal processing unit 14 compares the detection signal D with a preset set value V. At this time, since the detection signal D exceeds the set value at the point a, the comparison unit 18 outputs the output (2) to the delay unit 19 and the AND circuit 20. In the delay unit 19, the input output {circle around (2)} is input to the first waveform generation unit 21, and a square wave pulse S <b> 1 having a time width T <b> 1 from half cycle to one cycle of the commercial frequency power supply from the fall of the output {circle around (2)}. Is output. At this time, the first waveform generator 21 does not output the square wave pulse S1 even if a new output (2) is input from the comparator 18 while the square wave pulse S1 is being output.
[0032]
Then, the square wave pulse S1 from the first waveform generation unit 21 is input to the second waveform generation unit 22 and is longer than one cycle of the commercial frequency power supply from the falling edge of the pulse as in the first waveform generation unit 21. A square wave pulse S2 having an optimum time width T2 is output to the AND circuit 20.
[0033]
However, when the square wave pulse S2 from the second waveform generator 22 is input, the AND circuit 20 does not output the display signal P because there is no output {2} from the comparator 18 and displays an overcurrent. Never done. As described above, the overcurrent indicator 1 does not perform overcurrent display in a short time overcurrent generated by harmonics or the like. And the duration of the overcurrent which does not perform overcurrent display can be changed by adjusting the time width T1.
[0034]
Next, the operation when an overcurrent occurs in the electric wire 2 due to an accident or the like will be described with reference to FIG.
The load current I flowing in the electric wire 2 from which the display 1 is suspended is detected by the current detection unit 17, and the voltage induced in the winding 9 according to the current I is full-wave rectified and the detection signal D is sent to the signal processing unit 14. The comparison unit 18 of the signal processing unit 14 compares the detection signal D with a preset set value V. At this time, since the detection signal D exceeds the set value V at the point b, the comparison unit 18 outputs the output (2) to the delay unit 19 and the AND circuit 20. In the delay unit 19, the input output {circle around (2)} is input to the first waveform generation unit 21, and a square wave pulse S <b> 1 having a time width T <b> 1 from half cycle to one cycle of the commercial frequency power supply from the fall of the output {circle around (2)}. Is output. At this time, the first waveform generator 21 does not output the square wave pulse S2 even if a new wave output {circle around (2)} is input from the comparator 18 while the square wave pulse S1 is being output.
[0035]
Then, the square wave pulse S1 from the first waveform generation unit 21 is input to the second waveform generation unit 22 and is longer than one cycle of the commercial frequency power supply from the falling edge of the pulse as in the first waveform generation unit 21. A square wave pulse S2 having an optimum time width T2 is output to the AND circuit 20.
[0036]
The AND circuit 20 receives the square wave pulse S2 which is the output (2) from the comparison unit 18 and the output (4) from the second waveform generation unit 22, takes the logical product of both outputs, and displays the logical product when it is established. 5 and the display signal P are sent to the time measuring unit 24.
[0037]
In the display unit 5, when the display signal P is input, the transistor Tr1 is turned on, the electric charge stored in the capacitor C1 of the time measuring unit 15 flows through the display coil 28a, and the display plate 27 is driven to rotate 90 degrees. The colored portion 27a of the display plate 27 becomes visible from the outside through the display window 29a of the display cover 29, and overcurrent display is performed.
[0038]
At this time, when the display signal P is input to the time measurement unit 24, the time measurement unit 24 is reset, starts counting again for a certain time, for example, 5 hours, and outputs a return signal (not shown) after the completion of the 5 hour count. .
[0039]
Note that, at the end of the re-counting of the predetermined time, counting is started after the last display signal P ′ is input to the time measuring unit 24. Until then, the reset is applied every time the display signal P is input to the time measuring unit 24, and the 5-hour count is interrupted.
[0040]
After completion of the counting for 5 hours, the return signal turns on the transistor Tr2, and the charge stored in the capacitor C1 flows into the return coil 28b, causing the display board 27 to be rotated 90 degrees in the direction opposite to that during display. The colored portion 27a of the display board 27 is hidden by the display cover 29, and the colored portion 27a becomes invisible and the display is restored.
[0046]
【The invention's effect】
As described above, the overcurrent indicator of the present invention inputs the output of the comparison unit to the delay unit in the signal processing unit, thereby determining the overcurrent using the square wave pulse delayed in time and the output pulse of the comparison unit. As a result, the instantaneous overcurrent (about one cycle) generated by the harmonics and surge in the high-voltage distribution line is not erroneously detected, and erroneous display of the overcurrent display can be prevented.
[Brief description of the drawings]
FIG. 1 is a half sectional view of an embodiment of the present invention.
FIG. 2 is a block diagram of an embodiment of the present invention.
FIGS. 3A and 3B are views of the display unit according to the embodiment of the present invention as viewed from below, in which FIG. 3A shows an accident display state and FIG. 3B shows a return state.
FIG. 4 is a plan view of an embodiment of the present invention.
FIG. 5 is a front view showing a state in which an electric wire attachment portion is opened in the embodiment of the present invention.
FIG. 6 is a timing chart for explaining the normal operation of the embodiment of the present invention.
FIG. 7 is a timing chart for explaining the operation when harmonics are generated according to the embodiment of the present invention.
FIG. 8 is a timing chart for explaining the operation in the event of an embodiment of the present invention.
[Explanation of symbols]
1 Overcurrent indicator 2 High voltage distribution line (electric wire)
3 Wire Attachment 4 Body Case 5 Display Unit 14 Signal Processing Unit 17 Current Detection Unit 18 Comparison Unit 19 Delay Unit 20 AND Circuit 21 First Waveform Generation Unit 22 Second Waveform Generation Unit D Detection Signal I Current P Display Signal T2 Time span

Claims (1)

A current detection unit (17) that detects a current (I) flowing through the electric wire (2) such as a high-voltage distribution line and outputs a detection signal (D), and a signal that detects an overcurrent based on the detection signal (D) An overcurrent indicator comprising a processing unit (14) and a display unit (5) for displaying an overcurrent when the signal processing unit (14) detects an overcurrent,
The signal processing unit (14) includes a comparison unit (18) that outputs an output when the level of the detection signal (D) exceeds a preset level, and a delay from the output from the comparison unit (18). A delay unit (19) for outputting a square wave pulse having a constant time width (T2), and an AND circuit (20) for calculating a logical product of the output of the comparison unit (18) and the output of the delay unit (19), and an overcurrent display rows that are in the circuit (20) display unit in accordance with the output of the (5),
The delay unit (19) includes a first waveform generation unit (21) and a second waveform generation unit (22) that generate square wave pulses S1 and S2 having different time widths, respectively.
When the output of the comparison unit (18) is input to the first waveform generation unit (21), the first waveform generation unit (21) is triggered by the falling edge of the output to generate one square wave pulse S1 having a predetermined time width (T1). A one-shot multivibrator that does not output a new square wave pulse S1 even if there is an input from the comparator (18) during the output of the square wave pulse S1, and further, the fixed time width (T1) is It is set to a value between the length of half cycle to one cycle of commercial frequency power supply,
The second waveform generator (22) is triggered by the falling of the square wave pulse S1 output from the first waveform generator (21), and is one square wave having a certain time width (T2). Retriggerable one-shot multivibrator that outputs a pulse S2 and outputs a new square wave pulse S2 each time there is an input from the first waveform generator (21) during the output of the square wave pulse S2. And the constant time width (T2) is set to a value longer than one cycle (T) of the commercial frequency power supply .

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