JP7159379B2 - DETECTION DEVICE AND INSULATION RESISTANCE TEST METHOD AND SYSTEM - Google Patents

Description

The present invention relates to a detection device and an insulation resistance test method and system .

2. Description of the Related Art Conventionally, as a detection device, for example, an immersion pressure-type water level gauge for detecting a water level is known (see, for example, Patent Document 1). Since this type of water level gauge is mainly used outdoors, such as in waterways of water supply and sewerage facilities, rivers, etc., it is desirable to be grounded to enhance lightning resistance.

JP-A-11-201800

The inventors of the present invention have come to understand that simply grounding the water level gauge causes the problem that the metal portion of the detector is electrolytically corroded due to the flow of the ground current.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a lightning-resistant detector that does not cause problems such as electrolytic corrosion even when grounded.

In one aspect of the present invention, a detector grounded via an earth line receives a detection signal from the detector , and electrical insulation is ensured between the grounded receiver and the earth line . a signal line for transmitting the detection signal from the detector to the receiver ; A switch comprising:

With this configuration, the switch having a breakdown voltage greater than the ground voltage prevents ground current from flowing from the detector through the ground line. Therefore, it is possible to avoid damage to the metal parts of the detector due to electrolytic corrosion. On the other hand, since the breakdown voltage is smaller than the surge voltage, when a lightning surge occurs due to a lightning strike, etc., the current can escape through the ground line, preventing damage to the electronic equipment of the detector. . In other words, it has excellent lightning resistance.

Another aspect of the present invention is to prepare the above detection device, connect an insulation resistance meter to the first terminal connected to the ground line and the second terminal connected to the signal line, and provides an insulation resistance test method for measuring insulation resistance between the ground line and the signal line by applying an applied voltage greater than the breakdown voltage between the first terminal and the second terminal by do . Further, another aspect of the present invention is an insulation resistance test comprising the above detection device and an insulation resistance meter that applies an applied voltage higher than the breakdown voltage between the ground line and the signal line. provide the system.

According to this configuration, when a voltage is applied to the detector by the insulation resistance meter, the switch becomes energized, the current flows through the earth line, and the leak state in the detector can be detected.

The switch may be a surge absorber diode.

Another aspect of the present invention is a detector grounded through an earth line, a receiver that receives a detection signal from the detector, and a receiver that is connected to the middle of the earth line, has a voltage higher than the a surge absorber diode having a breakdown voltage less than the voltage; and a cable connecting said detector and said receiver, said detector comprising a housing made of a conductive material, said cable being connected to a signal line. and a terminal of the surge absorber diode electrically connected to the shield and the housing of the detector .

According to this configuration, simply by electrically connecting the surge absorber diode between the braided shield and the housing, it is possible to provide a configuration with excellent lightning resistance that is not easily subject to electrolytic corrosion.

The detector may be a water level detector placed in the liquid, and the receiver may be a repeater and transducer placed on the ground.

According to the present invention, the switch is connected in the middle of the ground line and has a breakdown voltage that is higher than the ground voltage and lower than the surge voltage. It is possible to have a configuration with excellent lightning resistance.

Schematic explanatory drawing of the detection apparatus which concerns on this embodiment. 2 is a cross-sectional view of the detector of FIG. 1; FIG. FIG. 3 is a cross-sectional view of the hollow cable of FIG. 2; FIG. 2 is a schematic explanatory diagram when an insulation resistance test is carried out with the detection device of FIG. 1;

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. It should be noted that the following description is essentially merely an example, and is not intended to limit the present invention, its applications, or its uses. Moreover, the drawings are schematic, and the ratio of each dimension is different from the actual one.

FIG. 1 shows a detection device according to this embodiment. This detection device comprises a detector 1 and a receiver 2 .

The detector 1 is, for example, an immersion pressure type water gauge. The basic configuration of the immersion pressure type water level gauge is the same as the conventional one (see, for example, Japanese Unexamined Patent Application Publication No. 11-201800). In the immersion pressure-type water level gauge, as shown in FIG. 2, the interior of a conductive metallic housing 3 is divided into an upper chamber 4 and a lower chamber 5 by a partition wall 7 having a central hole 7a. A differential transformer 6 is arranged in the upper chamber 4 . The differential transformer 6 has a cylindrical body 8 joined to the upper surface of the partition wall 7 . The tubular body 8 is a metal conductor, and the coil 9 is arranged on the lower side thereof. A bellows 10 is joined to the lower surface of the partition wall 7 . A spring 10 a is arranged between the lower end upper surface of the bellows 10 and the lower surface of the partition wall 7 . As a result, the bellows 10 is urged to protrude downward. An iron core 11 is integrated with the top surface of the lower end of the bellows 10 . The iron core 11 extends from the bellows 10 through the center hole 7 a into the cylindrical body 8 , and its tip is positioned inside the coil 9 . In addition, 12 is a frame for protecting the detector 1 .

In the detector 1 configured as described above, when the bellows 10 is deformed by the hydraulic head pressure, the iron core 11 is vertically displaced together with the bellows 10 . A displacement of the core 11 is converted into an electric signal by a coil 9 arranged around it. The converted electrical signals are output to the receiver 2 from signal lines 13a and 13b, which will be described later.

A hollow cable 13 is connected between the detector 1 and the receiver 2 in this embodiment. For example, as shown in FIG. 3, the hollow cable 13 consists of two signal lines 13a and 13b and one atmospheric pressure introduction pipe 13c surrounded by a pressure winding tape 13d and a braided shield 13e (for example, tin-plated soft steel braid). and a sheath 13f (for example, a heat-resistant vinyl sheath).

A switch 14 is electrically connected to the braided shield 13e, as shown in FIGS. A surge absorber such as a Zener diode, a varistor, or a surge absorber diode can be used for the switch 14 . In this embodiment, the switch 14 uses a surge absorber diode (hereinafter referred to as SAD). One end of the SAD 14 is electrically connected to the braided shield 13 e and the other end of the SAD 14 is electrically connected to the housing 3 of the detector 1 . As a result, a ground line composed of the SAD 14, the housing 3 and the liquid is formed between the braided shield 13e and the ground when the detector 1 is thrown into the liquid. The SAD 14 can be easily connected to the existing detector 1 as well. Specifically, if a part of the sheath 13f is peeled off, the exposed braided shield 13e is bundled, one end of the SAD 14 is connected and soldered, and the other end of the SAD 14 is screwed to the cylindrical body 8 of the differential transformer 6. good.

Receiver 2 comprises repeater 15 and converter 16 . The repeater 15 and the converter 16 are connected by a general cable 17 including transmission cables such as CVVS and hollow cables. Although not shown in detail, the cable 17 has a signal line covered with a braided shield, a sheath, or the like.

Although the details of the repeater 15 are not shown, the board is arranged in the housing 15a. A hollow cable 13 and a cable 17 are connected to the repeater 15 . The signal lines 13 a and 13 b of the hollow cable 13 and the signal line of the cable 17 are connected to the substrate, and the atmospheric pressure introduction pipe 13 c of the hollow cable 13 communicates with the housing 15 a of the repeater 15 . A braided shield 13 e of the hollow cable 13 is grounded via a first ground wire 18 . A braided shield 17 a of the cable 17 is grounded via a second ground wire 19 . For example, the first ground wire 18 can be switched between the second ground wire 19 and the first terminal 15b provided on the housing 15a by a switch SW. A second terminal 15c connected to the signal lines 13a and 13b of the hollow cable 13 is provided on the housing 15a. Both terminals of an insulation resistance meter 21, which will be described later, can be connected to the first terminal 15b and the second terminal 15c. Insulation resistance can be easily measured simply by switching the switch SW and connecting the insulation resistance meter 21 .

Although not shown in detail, the converter 16 has a power supply board arranged in a housing 16 a and is connected to the repeater 15 by a cable 17 . Power can be supplied to the repeater 15 via the signal line in the cable 17 . A braided shield 17 a of the cable 17 is grounded via a third ground wire 20 . The converter 16 may include a display for displaying the measured water pressure, the water level calculated based on the water pressure, and the like.

Next, a method for using the detection device having the above configuration will be described.

When measuring the water level, the detector 1 is placed in the liquid. By being placed in the liquid, the bellows 10 is displaced and the iron core 11 is moved, which is converted into an electric signal by the coil 9 arranged around it. The electrical signal is transmitted to repeater 15 via the signal line. The electrical signal input to the repeater 15 is output to the converter 16, and the detected water level is displayed or output as a voltage/current signal.

In the detection device, the SAD 14 is connected to the earth line. The metal portion of the detector 1 may be charged due to the potential difference between the detector 1 and the relay 15 . The ground voltage generated at this time ranges from 0.1V to 10V. On the other hand, the SAD 14 has a breakdown voltage greater than the ground voltage, for example, 10 to 50 V (actually, it is well above the maximum ground voltage of 10 V). A SAD14 with breakdown voltage is used). Therefore, no ground current flows through the ground line. Therefore, no electrolytic corrosion occurs in the metal portion of the detector 1 due to the earth current.

In addition, a lightning surge due to a lightning strike or the like may occur in the detection device. A range of 100 V or more is assumed for the surge voltage. The breakdown voltage of the SAD 14 is 10V to 50V as described above, which is a value smaller than the surge voltage. Since the SAD 14 breakdown voltage is less than the surge voltage, the lightning surge flows to ground through the ground line. Therefore, the detector 1 is not damaged by the lightning surge. In other words, it exhibits excellent lightning resistance performance.

By the way, in the detection device, it is necessary to perform an insulation resistance test periodically to confirm whether or not an electric leakage has occurred in the detector 1 .

The insulation resistance test is performed by connecting an insulation resistance meter 21 to the first and second terminals of the repeater 15 with the detector 1 pulled out of the liquid, as shown in FIG. In the insulation resistance test, the insulation resistance meter 21 applies a voltage between the first terminal 15b and the second terminal 15c. The applied voltage is greater than the breakdown voltage and less than the surge voltage, eg, 10V to 100V. Since the breakdown voltage can be in the range of 10V to 50V, the voltage applied by the insulation resistance meter 21 is selected to be a large value that can be distinguished from this value. Thereby, the insulation resistance can be measured between the housing 3 electrically connected from the first terminal through the braided shield 13e and the signal lines 13a and 13b connected to the second terminal. If the measured insulation resistance is greater than the preset reference value, it means that the desired insulation is secured between the housing 3 and the signal lines 13a and 13b, and the insulation state of the detector 1 is good. to decide. On the other hand, if the measured insulation resistance is smaller than the reference value, the signal lines 13a, 13b and the braided shield 13e are short-circuited, or the liquid flows into the detector 1 and stays therein, and the insulation is ensured. It is determined that the In this case, the user or serviceman may be warned by voice or display.

The detection device has the following effects.
(1) Since the switch 14 is simply connected to the detector 1, the detector can be manufactured with a simple structure and at a low cost. Moreover, the switch 14 can be easily attached to the existing detector 1 as well.
(2) Since the switch 14 does not conduct at the ground voltage, the ground current from the detector 1 does not cause electrolytic corrosion of the metal parts. In particular, when the hollow cable 13 connecting the detector 1 and the repeater 15 is long, the potential difference increases and the earth current tends to flow. .
(3) Since the switch 14 is energized by a surge voltage caused by a lightning strike or the like, the surge current can be released to the ground, and damage to the detector 1 can be prevented. In other words, it is possible to achieve a configuration with excellent lightning resistance performance.
(4) The switch 14 is connected to an insulation resistance meter and is energized by applying a voltage, so that the detector 1 can be tested for insulation resistance.
(5) The detector 1 has a simple structure that only incorporates the coil 9 and the like. And, as an electronic device, there is only the newly mounted SAD 14 . Therefore, even if it is handled roughly, such as being dropped into a river or pond, it is unlikely to break down. In particular, even when a surge voltage is applied, there are no electronic components that fail in the first place.

The present invention is not limited to the configurations described in the above embodiments, and various modifications are possible.

In the above embodiment, an example of an immersion pressure type water level gauge has been described as an example of the detector 1. However, it is not limited to this. of transducers 16 can be employed.

1 Detector 2 Receiver 3 Case 4 Upper Chamber 5 Lower Chamber 6 Differential Transformer 7 Partition Wall 8 Cylinder 9 Coil 10 Bellows 11 Iron Core 12 Frame 13 Hollow Cable 13a, 13b Signal Line 13c Atmospheric Pressure Introduction Pipe 13d Presser Winding Tape 13e Braided shield 13f Sheath 14 Switch 15 Repeater 15a Housing 15b First terminal 15c Second terminal 16 Converter 17 Cable 18 First ground wire 19 Second ground wire 20 Third ground wire 21 Insulation resistance tester

Claims (6)

a detector grounded via an earth line;
a grounded receiver that receives a detection signal from the detector;
a signal line provided so as to ensure electrical insulation from the ground line and transmitting the detection signal from the detector to the receiver;
a switch connected in the middle of the ground line and having a breakdown voltage higher than the ground voltage and lower than the surge voltage;
A detection device, comprising: 2. The detection device according to claim 1 , wherein said switch is a surge absorber diode. a detector grounded via an earth line;
a receiver for receiving a signal detected by the detector;
a surge absorber diode connected in the middle of the ground line and having a breakdown voltage higher than the ground voltage and lower than the surge voltage;
A cable connecting the detector and the receiver,
The detector comprises a housing made of a conductive material,
The cable comprises a shield made of a conductive material around the signal line,
A detection device, wherein terminals of the surge absorber diode are electrically connected to the shield and the housing of the detector. The detector is a water level detector placed in the liquid,
4. Detection apparatus according to any one of claims 1 to 3 , wherein the receiver is a terrestrially located repeater and transducer. a detector grounded via an earth line;
a grounded receiver that receives a detection signal from the detector;
a signal line provided so as to ensure electrical insulation from the ground line and transmitting the detection signal from the detector to the receiver;
a switch connected in the middle of the ground line and having a breakdown voltage greater than the ground voltage and less than the surge voltage;
connecting an insulation resistance meter to the first terminal connected to the ground line and the second terminal connected to the signal line;
Insulation resistance measuring insulation resistance between the ground line and the signal line by applying an applied voltage greater than the breakdown voltage between the first terminal and the second terminal by the insulation resistance meter. Test method. A detection device according to any one of claims 1 to 4;
an insulation resistance meter that applies an applied voltage greater than the breakdown voltage between the ground line and the signal line,
Insulation resistance test system.

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