JPH0477870B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a detection indicator that detects ground fault currents that occur due to damage and deterioration of power distribution equipment and power distribution equipment such as power cables.

Conventional technology Conventionally, display devices that are attached to a grounding wire and display a ground fault that occurs when the insulation of a distribution cable deteriorates have a current transformer that detects the ground fault current. In addition, since the operating power supply for the display unit that displays the ground fault display was separately provided, the display unit as a whole became large and heavy. As a result, attaching the display to a cable or the like is troublesome and the structure is complicated.

Purpose of the Invention The present invention has been made by focusing on the above-mentioned problem, and includes a device that is attached to a grounding wire to detect ground fault current in order to promptly discover fault points such as ground faults and short circuits in power distribution lines. The purpose of this invention is to provide a fault current detection indicator that does not require a separate power source for operation, has a simple structure, and can be made compact.As a result, it is easy to install and can be used both indoors and outdoors. be.

Structure of the Invention The fault current detection indicator of the present invention has a pair of terminals extending vertically on the sides of the frame, and a current transformer on the upper side of the frame whose primary side is connected to both terminals. attached to the lower part of the frame, connected to the secondary side of the current transformer,
A magnetic reversal display device is provided with a control circuit board provided with a control circuit that outputs a detected current using a transformed current from the current transformer when a fault current flows through the current transformer, and a magnetic reversal display device that displays a fault based on the detected current. This is what was placed.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 10, in which the present invention is applied to a ground fault indicator that indicates the passage of fault current in power cables and power distribution equipment.

In Figure 1, frame 1 of the ground fault indicator is
It is formed into a reverse channel shape in cross section by a support plate portion 1a and a pair of side plate portions 1b which are bent at right angles from both sides of the support plate portion 1a. Same frame 1
A cutout groove 2 is provided at the lower end of the support plate portion 1a.
A notch is formed in a U-shape, and locking pieces 3 are formed on both sides of the notch groove 2 to protrude inward from each other, and at the top of the notch groove 2 there is a groove narrower than the notch groove 2. An insertion groove 4 is provided. Furthermore, a through hole 5 is provided in the upper part of the support plate portion 1a of the frame 1.

A current transformer 6 is arranged on the back side of the support plate portion 1a of the frame 1. That is, in the current transformer 6, a hole 7 formed in the center around which the primary winding 6a and the secondary winding are wound is arranged corresponding to the through hole 5, and the hole 7, the through hole 5, It is tied to the support plate 1a by a string 8 wound through the insertion groove 4 and the upper end of the support plate 1a.

In the frame 1, mounting holes 9 are formed through the lower portions of both side plate portions 1b so as to face each other. A box-shaped transparent display case 10 is disposed between both side plate portions 1b of the frame 1. That is, the display case 10 has a second display window 10a.
As shown in FIGS. 3 and 3, locking step portions 11 are protruded from both sides thereof, and a mounting shaft 12 protruding from the side surfaces of the locking step portions 11 is inserted into and supported by the mounting hole 9. It is attached by this. The display case 10 is positioned by the side portions of the locking steps 11 engaging with the locking pieces 3 so as to protrude obliquely forward and downward through the notch grooves 2.

As shown in FIG. 3, a control circuit board 13 is adhesively fixed to the upper end of the display case 10 and is arranged to extend diagonally downward and rearward. A secondary winding wound around the transformer 6 is connected. Further, the display case 10 includes a magnetic reversal display device as a display section 14 to be described later.

A terminal 15 extending downward is fixed to one side plate portion 1b of the frame 1 by a plurality of rivets 16. A connecting piece 17 made of insulating synthetic resin extending upward is attached to the terminal 15 by the rivet 16, and the upper end of the connecting piece 17 is spaced apart from the frame 1 and the one terminal 15. The arranged terminals 18 are connected to multiple rivets 1
9, and its upper end extends upward. Both ends of the primary winding 6a of the current transformer 6 are connected to both terminals 18 and 15 by screws 20, respectively.

Around the frame 1, the current transformer 6, the control circuit board 13, the terminals 15 and 18, and the display case 10, except for the upper end surface of the terminal 18, the lower end of the terminal 15, and the display window 10a of the display case 10. A mold portion 21 made of a synthetic resin having excellent weather resistance and insulation properties, such as polyurethane, is formed to cover them.

The mold part 21 is formed into a truncated quadrangular pyramid shape so that it becomes wider toward the rear surface thereof, and protective walls 22 are provided on both sides of the upper surface thereof to protrude along the vertical direction. A return lever 23 is rotatably pivoted between the central portions of the protective wall 22.
3 is always biased by a coil spring 24 so as to be in the state shown by the solid line in FIG. A magnet 25 is attached to the back surface of the return lever 23. Further, a pair of band holes 26 are transparently provided near the top of both of the protection walls 22, through which a mounting band (not shown) can be inserted when the display device is attached to a telephone pole P (see Fig. 10), etc. It's summery. In addition, in FIG. 10, 35 is a switch attached to the arm Pa of the utility pole P.

Next, the control circuit provided on the control circuit board 13 will be explained with reference to FIG.

The primary winding of the current transformer 6 is connected in series with the grounding wire 27 of the power cable or distribution equipment (in this embodiment, the switch 35) via the terminals 15 and 18. A full-wave rectifier 28 is connected to both terminals of the secondary winding of the current transformer 6 via a choke coil L. Note that Z is a surge absorber connected between both terminals on the secondary side of the current transformer 6.
The display section 14 and a thyristor SCR as a switching element are connected in series to both the positive and negative terminals of the full-wave rectifier 28. This thyristor SCR has an anode connected to the display section 14 and a cathode connected to the negative terminal of the full-wave rectifier 28.

A capacitor C for charge storage is connected between the positive and negative terminals of the full-wave rectifier 28, as well as a capacitor discharge resistor R0, a Zener diode ZD as a thyristor temperature compensation element, and a gate voltage application resistor. A series circuit of a resistor R1 is connected.

The thyristor is connected to the positive terminal of the resistor R1.
The gate terminal of SCR is connected.

The Zener diode ZD is designed not to conduct unless a Zener voltage or higher is applied, and the Zener voltage is applied to the thyristor.
The resistor R1 is set so that a sufficient gate voltage is applied to the gate terminal to turn on the SCR even when the temperature is low, and the resistor R1 is set so that the Zener diode ZD conducts and the gate voltage supplied to the thyristor SCR is required when the temperature is low. Its resistance value is set to be equal to or higher than the gate trigger voltage.

To explain the display section 14, this display section 1
4 is a magnetic reversal display device, in which a disk 29 whose both ends are magnetized to N and S poles is rotatably supported around a rotating shaft 30, and a round bar-shaped stator 31 is connected to the S of the disk 29; Magnetic pole part 3 corresponding to the pole
2a and the magnetic pole portion 3 corresponding to the N pole of the disk 29
2b. Note that the stator 31 is preferably formed of a material with low coercive force. Between the two magnetic pole parts 32a and 32b, the same magnetic pole parts 32a and 32b are connected to the connection terminal of the display part so that they are magnetized to the same polarity with respect to the same end magnetic pole of the disk 29 in the state shown in FIG. A coil 33 is wound.

Front surface 34a and back surface 34b of the disk 29
Labels of mutually different colors (in this embodiment, the front side 34a is black and the back side 34b is red) are displayed.

When a detection current flows through the coil 33, the magnetic pole portion 32a becomes the S pole, as shown in FIG.
The magnetic pole portion 32b is magnetized to the north pole, and the disk 29 is reversely rotated so that its north pole faces the magnetic pole portion 32a (south pole) and its S pole faces the magnetic pole portion 32b (north pole). A label attached to the back surface 34b is displayed to the outside.

Furthermore, when the return lever 23 is rotated to the position shown by the chain line in FIG. 5, the display section 14 easily reverses the disk 29 by the magnet 25 attached to the return lever 23, and the normal position shown in FIG. It is now possible to return to a steady state.

In the display device of this embodiment, the indicator on the surface 34a of the disk 29 initially faces outward to indicate a steady state, as shown in FIG.

The operation of the display configured as above will be explained.

Now, the display device is attached to the utility pole P using a mounting band (not shown), and its terminals 15 and 18 are connected to the grounding wire 27 provided on the power cable and the power distribution equipment.

When a ground fault current flows through the grounding wire 27 due to deterioration of the power cable (not shown) in this installed state, a transformed current is outputted by the current transformer 6.
The transformed current charges the capacitor C after being rectified by the full-wave rectifier 28.

When the capacitor C is charged and the voltage increases and becomes higher than the Zener voltage of the Zener diode ZD and the Zener diode ZD becomes conductive, the resistor R1
A voltage across the thyristor SCR is applied between the gate and cathode of the thyristor SCR.

When a sufficient gate voltage is applied to the thyristor SCR, the thyristor SCR turns on and becomes conductive. Then, the charged capacitor C is discharged and current flows to the display section 14.

When a current flows through the coil 33 of the display section 14,
As shown in FIG. 9, the magnetic pole part 32a is magnetized to the S pole, and the magnetic pole part 32b is magnetized to the N pole. (pole).
As a result, the mark attached to the back surface 34b of the disk 29 is displayed to the outside to indicate a ground fault accident.

By viewing the mark on the back surface 34b from below, it can be determined that a ground fault has occurred in the grounding wire 27.

After the ground fault point has been discovered as described above, in order to restore the display, the return lever 23 is rotated against the coil spring 24 from the state shown in FIG. 5 to the state shown by the chain line. . Then, the disk 29 of the magnetic reversal display device is reversed by the magnetic force of the magnet 25 of the return lever 23 and returned to its original state, and is ready to respond to the next ground fault. Note that when the return lever 23 is released from its operating force, the coil spring 24
It rotates back to its original state due to the biasing force of .

Furthermore, in general, a thyristor turns on with a low gate voltage when the temperature rises, and turns on with a high gate voltage when the temperature drops, so its operation is unstable depending on the temperature. However, since the Zener voltage of the Zener diode ZD is set to a predetermined voltage, even if a ground fault current flows in a state where the ambient temperature is high, the gate has sufficient voltage until the Zener diode ZD reaches the Zener voltage. No voltage is applied, so thyristor SCR does not turn on. When the voltage across the Zener diode ZD reaches a predetermined voltage and becomes conductive, the thyristor SCR
The gate voltage is applied to the thyristor.
SCR becomes conductive.

Also, if a ground fault current flows at a low temperature, the thyristor SCR is activated only when the voltage across the Zener diode ZD reaches the Zener voltage, similar to the case at a high temperature.
becomes conductive because a sufficient gate voltage is applied to its gate.

In this embodiment, the thyristor SCR can operate stably even when the temperature changes as described above.

Furthermore, since this display device uses a current transformer, it hardly affects the grounding resistance value of the grounding wire 27.

Furthermore, in the past, this type of display used a relay coil in the control circuit for driving the display, which required the use of a large current transformer, but in this embodiment, the control circuit uses a large current transformer. Since no relay coil is used, the output energy of the current transformer 6 can be small, and the current transformer 6 can be downsized. Thereby, the entire display can be made compact.

Furthermore, in the control circuit of this embodiment, the thyristor
The SCR gate circuit is usually a Zener diode.
Since it is blocked by the ZD, the thyristor SCR will not malfunction due to radio waves, and it can reliably respond to only the fault current and display the fault.

The ground fault indicator configured as described above can detect ground fault current and does not require a separate operating power source, so the structure can be simplified and the indicator can be made smaller. Therefore, the overall weight of the display device is reduced, the installation work becomes simple, and the efficiency of the installation work can be improved.

In addition, since the current transformer 6, which takes up a relatively large space, is placed at the top of the frame 1, and the display case 10 is placed at the bottom of the frame 1, there is nothing below the display window 10a that obstructs visibility. The visible range can be freely set. That is, by freely changing the mounting angle of the display case 10 during assembly, the visible range can be changed.

Also, since the entire unit is molded with weather-resistant synthetic resin, it can be used both indoors and outdoors.

Note that the present invention is not limited to the above-mentioned embodiment, and for example, as shown in FIG.
Instead of the series circuit of ZD and resistor R1, a series circuit of Zener diode ZD, resistor R1, and resistor R2 is connected to both terminals of the full-wave rectifier 28, and the gate terminal of the thyristor SCR is connected to the positive terminal of resistor R1. good. By doing so, when the Zener diode ZD becomes conductive, the capacitor voltage is divided between the resistors R2 and R1, and the voltage across the resistor R1 is applied between the gate and cathode of the thyristor SCR.

The effects in this case are the same as those in the previous embodiment.

Effects of the Invention As detailed above, the present invention provides a frame with a current transformer, a control circuit that outputs the current detected by the current transformer, and a fault indication based on the detected current from the control circuit. It has a simple structure with a magnetic reversal display device, and does not require a separate power source for operation, so it can be designed very compactly, and the display disk can be reset with a single touch of a lever, making it easy to quickly find the point of an accident. This is an excellent invention for industrial use.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the main parts of a display device according to an embodiment of the present invention excluding the mold part, FIG. 2 is a partially cutaway front view, FIG. 3 is a side view, and FIG. FIG. 5 is a partially cutaway side view of this display, FIG. 6 is a bottom view of the entire display, FIG. 7 is a control circuit diagram of this display, and FIG. 8 is a perspective view of the main parts of the display. FIG. 9 is a perspective view showing the operation of the main parts of the display section, FIG. 10 is a side view of the display in an attached state, and FIG. 11 is a control circuit diagram of another example of the display. DESCRIPTION OF SYMBOLS 1... Frame, 6... Current transformer, 10... Display body case, 13... Control circuit board, 14... Display part, 1
5, 18...Terminal, 21...Mold part, 23...Return lever, 25...Magnet, 26...Band hole, 27...Grounding wire, 28...Full wave rectifier, 29...Disc, 30
...Rotation axis, 31...Stator, 33...Coil,...
Display, SCR...Thyristor, R0, R1, R2
...Resistor, C...Capacitor, ZD...Zener diode.

Claims (1)

[Claims] 1 A pair of terminals extending vertically are arranged on the sides of the frame, a current transformer whose primary side is connected to both terminals is attached to the upper part of the frame, and a current transformer whose primary side is connected to both terminals is attached to the lower part of the frame. A control circuit board is disposed that is connected to the secondary side of the current transformer, and is provided with a control circuit that outputs a detected current based on a transformed current from the current transformer when a fault current flows to the current transformer. A fault current detection indicator characterized by having a magnetic reversal display device that displays faults using current.