JPH0316064Y2 - - Google Patents

Description

[Detailed description of the invention] A. Field of industrial application The invention is used in a self-diagnosis circuit of a voltage detector that distinguishes between low voltage and high voltage to detect whether or not an AC circuit is charged.

B. Prior art As a voltage detector to detect the presence or absence of charge in electrical circuits, etc.
Although the charging voltage is low (e.g. 100v~200v),
Alternatively, devices have already been devised that distinguish and detect whether the voltage is high voltage (for example, 600v or higher). The configuration of this conventional device is shown in Fig. 1. Reference numeral 1 indicates an electric path for detecting whether or not it is charged, 2 indicates a detection metal fitting for voltage detector D, 3 indicates a resistor for current limiting, and 4 indicates a low capacity (e.g. Several PF) input capacitor, 5 is voltage detector D
The stray capacitance formed between the voltage detector D and the earth by an inspector holding a
A low voltage detection circuit configured to output when a voltage of 65v or more is input, 7 is a high voltage detection circuit configured to output when a voltage of 350v or more is input to the detection fitting, 8 is a low voltage 9 is an intermittent signal generation circuit that outputs an intermittent signal when the detection circuit 6 outputs it; 9 is an acoustic oscillation circuit that oscillates when the intermittent signal generation circuit 8 or the high voltage detection circuit 7 outputs; 10;
is an alarm consisting of a buzzer 10a and a lamp 10b, and performs an alarm operation based on the output of the acoustic oscillation circuit 9;
Reference numeral 11 denotes a power supply battery that supplies the operating voltage of this voltage detector D.

This voltage detection operation using the voltage detector D is performed by bringing the detection metal fitting 2 of the voltage detector D into contact with the electric line 1 that is the object of voltage detection. If the electric circuit 1 is charged at this time, the detection fitting 2, the current limiting resistor 3, the input capacitor 4,
A small current flows to the ground through the floating capacitance 5 and the floating capacitance 5. As a result, the voltage detection operation performed by detecting the voltage charged in the input capacitor 4 is performed when the electric line 1 is not charged, (b) when the electric line 1 is charged at low voltage,
When charging at high voltage, each of (c) is performed as follows.

In the case of no charging, neither the low voltage detection circuit 6 nor the high voltage detection circuit 7 outputs an output, and no notification operation is performed.

In the case of low voltage charging, only the low voltage detection circuit 6 outputs, and the intermittent signal generation circuit 8 generates an intermittent signal, so the buzzer 10a and lamp 10b of the alarm 10 adjust the generation cycle As a result, intermittent notification operations are performed using sound and light emission.

When the battery is being charged at a high voltage, both the low voltage detection circuit 6 and the high voltage detection circuit 7 output an output. In this case, since the output of the high voltage detection circuit 7 is directly output to the acoustic oscillation circuit 9, the buzzer 10a and the lamp 10
b performs continuous notification operation by sound and lighting.

Therefore, as stipulated in Article 352 of the Industrial Safety and Health Regulations, such voltage detector D must be inspected for voltage detection performance (operation) before it is used on the same day. In order to easily carry out this inspection, a circuit may be provided as a self-diagnosis circuit that uses the power supply battery 11 to input the respective operation start voltages to the low voltage detection circuit 6 and the high voltage detection circuit 7. However, since the operating start voltage of the low voltage detection circuit 6 and the operating start voltage of the high voltage detection circuit 7 are different, the circuit means and their operation will be complicated if the voltage detection performance of each is to be checked. . In other words, as shown by the dashed line in Figure 1, the voltage dividing resistor
A self-diagnosis circuit 12 must be incorporated having two test switches SW ₁ and SW ₂ that separately apply two voltage levels obtained by R ₁ , R ₂ , R ₃ , etc.

The configuration in which two test switches SW ₁ and SW ₂ are provided in this way not only complicates the structure and increases costs, but also increases the number of test switches SW 1 and SW ₂ .
Operability deteriorates due to pressing SW ₂ incorrectly.

C. Purpose of the invention The purpose of the invention is to provide a voltage detector that can check the functions of the entire device, such as the voltage detection functions of the low-voltage detection circuit and high-voltage detection circuit and battery life, by operating one test switch only once. shall be.

D. Composition of the invention The invention consists of a detection fitting that is brought into contact with an alternating current electric circuit;
An input circuit consisting of a current limiting resistor, an input capacitor, and a stray capacitance between a voltage detector and ground connected in series, and a low voltage detection circuit that detects whether the charging voltage of this input capacitor exceeds a predetermined level. and a voltage detector having a high voltage detection circuit and an alarm that distinguishes and notifies low voltage detection and high voltage detection based on the output of the low voltage detection circuit and the output of the high voltage detection circuit, and an automatic return having a normally open contact and a normally closed contact. It consists of a single type test switch, a self-diagnosis capacitor that has a much larger capacity than the input capacitor and is connected in parallel to the input capacitor, a resistor, the normally open contact of the above test switch, and a power supply battery that are connected in series. When the test switch is pressed, the charging circuit supplies the test voltage to both ends of the parallel circuit of the input capacitor and self-diagnosis capacitor, and the charging current from the power supply battery flows through both capacitors with the polarity. The test switch is separated from the first and second backflow prevention diodes inserted and connected between one power supply point of the circuit and the input capacitor, and between the other power supply point of the charging circuit and the self-diagnosis capacitor. A self-diagnosis circuit is provided, which includes a rapid discharge circuit for discharging the charge in the self-diagnosis capacitor through the normally closed contact of the test switch when the test switch is in the state.

E. Embodiment FIG. 2 shows the external appearance of a voltage detector according to an embodiment of the present invention, FIG. 3 shows its internal structure, and FIG. 4 shows its circuit configuration.

In FIGS. 2 and 3, 13 is a cylindrical electroscope main body, 14 is an insulating holding part that is fixed to the front part of the electroscope body 13 and has insulation folds on the outer periphery, and 2 is embedded in the tip of the insulating holding part 14. A fixed detection metal fitting 3 is sealed with an insulating material 15 such as a synthetic resin in an insulating holding part 14 and is connected to the detection metal fitting 2, and a current limiting resistor 16 is a cylindrical shape fixed to the rear part of the voltage detector body 13. 17 is a lid that closes the tail of the grip 16, 18 is a wiring board for circuit assembly, 10a is a buzzer for notification, 10b is a lamp for notification, 19 is a transparent lamp window, and 11 is a power source battery. , SW is a test switch, and 20 is a push button of the test switch made of an elastic material such as rubber.

An electric circuit as shown in FIG. 4 is incorporated into the wiring board 18. In FIG. 4, the same reference numerals as in FIG. 1 indicate the same components, and the difference is that a self-diagnosis circuit 21 using only one test switch SW is incorporated.

That is, in this self-diagnosis circuit 21, SW is an automatic reset type test switch having a normally open contact a and a normally closed contact b, and 22 is the input capacitor 4.
has a significantly larger capacitance (e.g. several μF) than
A CR circuit in which a self-diagnosis capacitor C is connected in parallel to the input capacitor 4, and a resistor R is connected in series.
D ₁ and D ₃ are the first and second capacitors which prohibit the supply of current from the input capacitor 4 side to the self-diagnosis capacitor C and electrically separate the input capacitor 4 from the self-diagnosis circuit 21 during voltage detection operation. The backflow prevention diode, _D2 , is a rapid discharge diode that allows the device to immediately begin voltage detection operation after the self-diagnosis is completed.

The voltage detector D is operated by grasping a grip part 16 fixed to the rear part of the voltage detector main body 13 by hand, and bringing the detection fitting 2 at the tip into contact with the electric line 1, which is the part to be tested. The operation in this case is similar to that of the conventional voltage detector D described above. Note that during this voltage detection operation, positive and negative voltages derived from the AC circuit 1 appear across the input capacitor 4, but the first and second backflow prevention diodes D ₁ and D ₃ are inserted. For,
This voltage prevents current from flowing into the self-diagnosis capacitor C. In this way, currents due to positive and negative voltages are blocked during voltage detection operation, and the input capacitor 4 is made independent from the capacitor C of the self-diagnosis circuit, so that charging of the input capacitor 4 by the minute stray capacitance 5 is prevented. It becomes possible. Furthermore, since the self-diagnosis capacitor C is not charged by the voltage led from the electric circuit 1, self-diagnosis can be performed using a test voltage that always has a constant rising characteristic.

Next, the operation of the self-diagnosis circuit 21, which is a feature of the present invention, will be explained.

When the push button 20 of the test switch SW is pressed with the detection fitting 2 separated from the electric circuit 1, the normally open contact a closes. From a charging circuit configured by connecting a resistor R, a normally open contact a, and a power supply battery 11 in series,
A test voltage is charged to the parallel circuit of the input capacitor 4 and the self-diagnosis capacitor C. Note that the first and second backflow prevention diodes D ₁ and D ₃ are in the forward direction with respect to this charging current, and their forward voltage drop is negligible. The charging voltages of the input capacitor 4 and the capacitor C of the self-diagnosis circuit gradually rise while maintaining the same level, and the charging voltage of the input capacitor 4 is applied to the low voltage detection circuit 6 and the high voltage detection circuit 7. Since the capacitance of the self-diagnosis capacitor C is selected to be considerably larger than that of the input capacitor 4, this voltage rise characteristic is hardly affected by the charging current to the input capacitor 4, and the resistance of the resistor R It is approximately determined by the size and the capacity of the self-diagnosis capacitor C. In other words, after starting the self-diagnosis, the low voltage voltage detection circuit 6
The voltage e input to the high voltage detection circuit 7 rises with the characteristic of e=E(1-ε-1/CRt).

When the voltage detector D' is normal, the low voltage detection circuit 6 first outputs an output, and then after a predetermined time, the high voltage detection circuit 7 outputs an output. Therefore, the acoustic oscillator circuit 9 first oscillates at intervals of the intermittent signal generated by the intermittent signal generating circuit 8, causing the buzzer 10a and lamp 10b of the alarm 10 to perform an intermittent operation. After this, when a predetermined period of time (for example, 2 to 3 seconds) has elapsed, the high voltage detection circuit 7 also starts outputting, so the acoustic oscillation circuit 9 shifts to continuous oscillation operation, and the buzzer 10a and lamp 10b of the alarm 10 turn off. Becomes a continuous motion. During this test operation, the time until the first operation starts and the intermittent operation time can be determined as appropriate by selecting the capacitance of the self-diagnosis capacitor C and the size of the resistor R. .

Furthermore, if the voltage detector D' is defective, it can be known from the following test results.

If the low pressure detection circuit 6 is defective, the alarm 10 does not perform the initial intermittent operation, but only performs continuous operation.

If the high voltage detection circuit 7 is defective or the power supply battery 11 is deteriorated, the high voltage detection circuit 7 will not output, or the charging voltage of the self-diagnosis capacitor C of the CR circuit will be charged to the level that the high voltage detection circuit 7 outputs. Therefore, the alarm 10 operates only intermittently. In this case, the power supply battery 11 is checked and if it is normal, it can be determined that the high voltage detection circuit 7 is defective.

When the test operation is completed as described above, release the test button 20 of the test switch SW. Then, the test switch SW is connected to the normally closed contact b, so the charge on the capacitor C of the CR circuit 22 is
It is rapidly discharged through a rapid discharge circuit consisting of a rapid discharge diode _D2 and a normally closed contact b. Since the minute amount of charge in the input capacitor 4 is discharged through the input impedance of the low voltage detection circuit 6 and the high voltage detection circuit 7, its voltage follows the voltage across the self-diagnosis capacitor C and decreases. Therefore, the original voltage detection operation can be performed immediately after the test operation.

Note that the alarm 10 may be any device as long as it calls the operator's attention, and any means other than the buzzer 10a and lamp 10b as described above may be employed.

F. Effect of the invention According to the invention, in a voltage detector that has two detection levels of low voltage and high voltage, the low voltage detection circuit and high voltage detection circuit of the voltage detector can be checked continuously with just one operation of one test switch. We can provide a self-diagnosis circuit that can Therefore, compared to the case where two test switches are used, the voltage detector can be made more compact, and the operability of the test can be significantly improved.
Furthermore, during this test operation, the functions of the entire voltage detector, such as the alarm and the power supply battery, can be checked, making the voltage detector extremely practical.

[Brief explanation of the drawing]

Figure 1 shows an example of the circuit of a conventional voltage detector;
The figure is a side view showing the external shape of a voltage detector according to an embodiment of the present invention, and FIG. 3 is a sectional view taken along line A-A in FIG.
FIG. 4 is an electrical circuit diagram of the voltage detector shown in FIGS. 2 and 3. 1... Electric circuit, 2... Detection metal fitting, 6... Low voltage detection circuit, 7... High voltage detection circuit, 10... Alarm, 1
1...Power battery, 21...Self-diagnosis circuit, 22...
...CR circuit, D'...Voltage detector, SW...Test switch, R...Resistor, C...Capacitor for self-diagnosis.

Claims (1)

[Scope of Claim for Utility Model Registration] An input circuit consisting of a detection metal fitting that contacts an AC circuit, a current limiting resistor, an input capacitor, and a stray capacitance between a voltage detector and ground connected in series;
A low voltage detection circuit and a high voltage detection circuit detect whether or not the charging voltage of this input capacitor exceeds a predetermined level, and low voltage detection and high voltage detection are distinguished and notified by the output of the low voltage detection circuit and the output of the high voltage detection circuit. In voltage detectors, there is one test switch of the automatic reset type with normally open and normally closed contacts, and a self-diagnosis test switch that has a considerably larger capacity than the input capacitor and is connected in parallel to the input capacitor. It consists of a capacitor, a resistor, the normally open contact of the above test switch, and a power battery connected in series, and when the test switch is pressed, a test voltage is supplied to both ends of the parallel circuit of the input capacitor and self-diagnosis capacitor. A charging circuit with polarity in which the charging current from the power supply battery flows through both capacitors, between one power supply point of the charging circuit and the input capacitor, and between the other power supply point of the charging circuit and the self-diagnosis capacitor. and a rapid discharge circuit that discharges the charge in the self-diagnosis capacitor through the normally closed contact of the test switch when the test switch is released. A voltage detector characterized by being equipped with a self-diagnosis circuit.