JPS6210692Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an insulation deterioration indicator that indicates when a ground fault occurs due to deterioration of insulation in a cable that is often used as a private lead-in line for high-voltage distribution lines.

As a conventional insulation deterioration indicator, a circuit shown in FIG. 4 is known. (In FIG. 4, parts that are considered to have a functionally equivalent configuration to the embodiment of the present application described later are given the same reference numerals and an alphanumeric character f, and their explanations are omitted.) , when the switch 25f is closed, the relay coil 22 with a large resistance value is connected to the solenoid 24f.
Since a current flows through f, the current is limited to a small value, and the solenoid coil 24f becomes insufficiently excited, causing the movable element (movable element 4 in the embodiment of the present application to be described later).
0) had the disadvantage that the operation was uncertain and the display operation was insufficient.

Therefore, the present invention aims to eliminate the above-mentioned drawbacks and to provide an insulation deterioration indicator that can display information with high reliability and reliability.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings 1 to 3 showing embodiments of the present application will be described below. In FIG. 1, 1 is a substation busbar, 2 is a circuit breaker, 3 is a high-voltage distribution line, 4 is a high-voltage drop-in cable, 5 is a conductor in the cable 4, and 6 is a shielding metal body in the cable 4. Reference numeral 7 denotes an insulation deterioration indicator, which is interposed in the middle of a grounding line 8 that grounds the shielding metal body 6.

Next, in FIG. 2 showing the circuit of the insulation deterioration indicator 7, 10 is an input terminal, which is a terminal connected to the shielding metal body side of the grounding wire 8. 11 is a connection terminal,
This is a terminal connected to the ground side of the ground wire 8. 12
is an arrester, and a vacuum arrester is used.
13 is a saturable reactor, and even if an abnormally large current flows through the primary winding 13a, the secondary winding 1
3b has a characteristic that only a constant voltage appears. 14 is a minimum operating current switching circuit, which selects the lowest value of the primary current (earth fault current) that can be detected by this display 7 by switching the resistor 16 or 17 with the selector switch 15 (for example,
400mA and 800mA). Note that this circuit 14 may be replaced with a variable resistor.
A limiting resistor 18 is used to set the minimum operating time of this display, and by changing the value of this resistor, the time can be changed. 19
is a capacitor which, together with the resistor 18, protects the next rectifier by suppressing intruding pulses and the like. 20 is a rectifier, for example a bridge type one is used. 21 is a capacitor for charge storage, and 22 is a relay coil. As an example, a reed relay coil with a resistance value of several 100 Ω is used. Reference numeral 23 denotes a sensitivity adjustment resistor that adjusts the operational sensitivity of the reed relay to the current flowing through the primary winding 13a of the saturable reactor 13, and is, for example, several kilohms. 24
is a solenoid coil, and as an example, one with a resistance value of several Ω is used. 25 is a normally open switch, for example, the contact of the reed relay mentioned above is used,
The circuit is closed when the relay coil 22 is excited. Note that a normal relay may be used instead of the reed relay described above. 26 is a diode,
As shown in the figure, the connection circuit between the relay coil 22 and the resistor 23 and the connection circuit between the solenoid coil 24 and the switch 25 are connected in the direction shown in the figure.

Next, in FIG. 3 showing the display mechanism in the display 7, 27 is the case of the display 7, 28 is the display body, which is configured to be freely movable in the directions of arrows 29 and 30, and is in the normal position shown by the solid line. and the abnormal position shown by the imaginary line. Further, this display body 28 is biased by gravity in the direction of an arrow 29 (vertically downward). Note that this biasing may be performed using any spring. Reference numerals 31 and 32 indicate the display parts of the display body 28, which are colored, for example, in white and red. In a normal state, only the white display part 31 is displayed, and in an abnormal state (when insulation deteriorates), the white display part 31 and the red display part 31 are painted. Both of the display parts 32 protrude below the case 27, so that the status can be recognized at a glance. (Note that the protruding direction is not limited to the downward direction of the case, but may also be to the side or upward.) 33 indicates an engaging piece in the display body 28, the upper surface of which is round as shown in the figure, and the lower surface is flat. The engagement surfaces 34 are each configured to have a shape. Reference numeral 35 indicates a solenoid provided within the case, which is composed of an iron core 36, the solenoid coil 24, and a plunger 37, as is well known. Reference numeral 38 denotes a locking piece fixed to the plunger 37, the lower surface of which is round as shown, and the upper surface formed into a locking stepped portion 39 as shown. In this specification, the member consisting of the plunger 37 and the locking piece 38 is also referred to as a mover 40. This movable element 40 is biased to the right in FIG. 3 by a spring not shown,
The step portion 39 normally locks the engagement surface 34.

In the case of the above configuration, the insulation between the conductor 5 and the shielding metal body 6 in the lead-in cable 4 deteriorates, and a current (earth fault) flows from the conductor 5 into the ground via the shielding metal body 6 and the grounding wire 8. When a current) starts to flow, the current flows through the primary winding 13a of the saturable reactor 13, and a voltage is induced in the secondary winding 13b, causing a current to flow. This current is rectified by a rectifier 20 and stored in a capacitor 21. When the voltage across the capacitor 21 reaches a predetermined value, the switch 25 is closed by excitation of the relay coil 22. When the switch 25 is closed, the solenoid coil 24 is directly connected to the capacitor 21, so a large current necessary for starting the solenoid coil 24 flows, and the plunger 37 begins to be pulled to the left in FIG. 3 with a large force. In addition, in this state, due to the closing of the switch 25, a sufficiently large current flows through the relay coil 22 along the path indicated by the arrow 41.
Lock switch 25 in the closed position. As a result, the energization of the solenoid coil 24 is reliably maintained, and the movement of the plunger 37 in the above direction is reliably continued. Due to the movement of the plunger 37 as described above, the locking step portion 39 of the locking piece 38 is moved to the engagement piece 33.
It comes off from the engagement surface 34 of. Then, the display body 28 moves in the direction of the arrow 29 due to the biasing force applied thereto and is displaced to an abnormal position, continuously indicating that insulation deterioration has occurred in the cable.

After the cable 4 accident recovery work is completed, by manually pushing the indicator 28 in the abnormal position in the direction of the arrow 30, both the upper surface of the engaging piece 33 and the lower surface of the locking piece 38 will be moved as described above. Because of this, the display body 28 can be easily returned to its normal position.

As described above, in this invention, when the insulation of the high-voltage drop-in cable deteriorates and a ground fault current begins to flow through the shielding metal body 6 of the drop-in cable 4, the current is transferred to the saturable reactor 13. After it is picked up, it is rectified by a rectifier 20 and stored in a charge storage capacitor 21. When the charge accumulated in the capacitor 21 reaches a predetermined value, the charge is passed through the solenoid coil 24 to operate the movable element 40. Therefore, the display body 28, which is always biased toward the abnormal position, is released from the lock, so that the display body 28 can move to the abnormal position by itself.
The above case has the advantage that insulation deterioration can be displayed while the display body 28 remains moved to the abnormal position. This means that because of the structure of the high-voltage drop-in cable 4, it is difficult to determine whether the insulation has deteriorated from the outside, and even if a ground fault occurs due to insulation deterioration, the ground fault will recover naturally, making it difficult to detect a failure. Even if the display body 28 is moved to the abnormal position, it is possible to quickly and reliably indicate the deterioration of the insulation or the occurrence of a ground fault.

Moreover, even if the above-mentioned system constantly monitors the occurrence of insulation deterioration of the high-voltage drop-in cable and displays the above-mentioned display when insulation deterioration occurs, the operation is such that the current caused by insulation deterioration is As mentioned above, it is stored in the capacitor 21 for charge storage,
Since the accumulated charge is used as a power source to release the lock, there is no need to supply an external power source for operation, and there is an economic advantage in that the maintenance cost can be eliminated.

Furthermore, even if the charge stored in the capacitor 21 is used as a power source as described above, in the present invention, the solenoid coil 24
is the above capacitor 2 in series with the normally open switch 25.
A relay coil 22 for closing the switch 25 is connected to the capacitor 21 in series with a resistor 23 for sensitivity adjustment, and a diode 25 is connected between the relay coil 22 and the switch 25. Therefore, when the electric charge reaches the predetermined value and the solenoid coil 24 is excited to operate the mover 40, the switch 25 is first closed and the solenoid coil 24 is activated. A large current necessary for the relay coil 2 can be passed at an early stage, and the movement of the movable element 40 can be reliably started.
2 through the diode 26 to the switch 25, the switch 25 is locked in the closed state to maintain the excitation of the solenoid coil 24, and the movable element 40 is moved. It has the advantage of ensuring that it continues.
This has the effect that the display body 28 can be reliably unlocked and the display operation as described above can be performed reliably.

[Brief explanation of the drawing]

The drawings show an embodiment of the present application; FIG. 1 is a connection system diagram, FIG. 2 is a circuit diagram, FIG. 3 is a schematic diagram of a display mechanism, and FIG. 4 is a diagram showing an example of a conventional circuit. 4... High voltage lead-in cable, 6... Shielding metal body,
21... Capacitor, 22... Relay coil, 2
4...Solenoid coil, 25...Switch, 2
6...Diode, 28...Display body, 40...Movable element.

Claims (1)

[Scope of utility model claims] One end of the primary winding of the saturable reactor is connected to the shielding metal body of the high voltage lead-in cable, and the other end is grounded. Furthermore, a series circuit consisting of a solenoid coil and a normally open switch is connected to both ends of the capacitor, and an indicator is provided that allows displacement between the normal position and the abnormal position. The display body is biased toward the abnormal position, and a mover is attached to the display body, which is activated by energizing the solenoid coil. In this state, the movable element locks the display body in the normal position against the above-mentioned bias, and when the solenoid coil is energized and the movable element is activated, the display body is unlatched. In the insulation deterioration indicator, a series circuit consisting of a relay coil and a sensitivity adjustment resistor is connected to both ends of the capacitor to close the switch when the capacitor is energized.
One end of the relay coil is connected to one end of the solenoid coil, and a diode is connected between the connection circuit between the relay coil and the sensitivity adjustment resistor and the connection circuit between the solenoid coil and the switch, Moreover, the diode is connected in such a direction that current flows through the relay coil, the diode, and the switch when the switch is closed.