JP3315622B2 - Cable checker - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved cable checker for checking the voltage and continuity of a cable and a method of checking the cable.

[0002]

2. Description of the Related Art In electrical works such as substation works, securing safety and ensuring smooth equipment operation are the most important issues. In a substation, a large number of control cables are used for control, and a voltage check and a continuity check are indispensable for the work of connecting and disconnecting the control cable. The voltage check is for confirming that the cable to be disconnected is not a current conducting cable (hot wire), and is an operation for avoiding a failure caused by accidentally disconnecting a hot wire being used. In addition, the continuity check ensures that both ends of the cable are both ends of one cable without error. In particular, avoiding mistakes in which the end of a cable is mistaken for the end of another cable because there are many cables It is work to do.

In performing these voltage check and continuity check, the continuity check must always be performed after the voltage check. That is, the devices that perform the voltage check and the continuity check are called a voltage checker and a continuity checker, respectively. The internal resistance of the voltage checker is very large, whereas the internal resistance of the continuity checker is very small. For this reason, if a live line is connected to the ground through the continuity checker and a continuity check is performed, a short circuit or ground fault may occur, and a trouble such as a mistrip accident or arc burn may occur. In particular, the three-phase short-circuit current of the low-voltage AC circuit in the primary substation is several tens of kA, which may cause not only burns but also injuries such as blindness.

FIGS. 32 to 34 show an example in which a voltage check is performed by a voltage checker, and a buzzer and a fuse clip are used as a continuity checker. That is, first, it is confirmed by the voltage checker V that there is no voltage at both ends of the cable W (FIG. 32), and a continuity check is performed (FIG. 3).
3). In the continuity check, one end of the cable is connected to ground by a fuse clip FC, and the other end is connected to ground via a buzzer BZ provided with a battery.
If both ends of these cables are correctly both ends of the same cable, a current flows through a circuit constituted by the cable W and the ground, and the buzzer BZ sounds. However, if the cable W subjected to the continuity check is a live line, a ground fault or a short circuit occurs through a circuit configured for the continuity check (FIG. 34). Disturbance occurs.

Next, a specific example of such a ground fault will be described. For example, FIG. 35 is a diagram illustrating a part of a control circuit using DC current in a substation or the like. As shown in this figure, the positive P and the negative N have a potential difference of 100 V between them, and none of them is directly connected to the ground. The plus P and the minus N are connected by two high resistances R, and an intermediate point between the two high resistances R is grounded via a DC ground fault detection relay 64DRy. In such a control circuit, when a ground fault occurs due to component deterioration or work error, the high resistance R prevents a short circuit between the positive P and the negative N. Then, in the case of the plus side ground fault, a route 3 indicated by a broken line
51, in the case of a negative side ground fault, a ground fault current flows as indicated by a path 352 shown by a broken line, and the polarity of the ground fault is determined by the relay 64DR.
detected and reported by y.

In the control circuit shown in FIG. 35, when the control cable with the hot wire is grounded by a tester T having a small internal resistance, a ground fault current flows as indicated by a broken line 353, and the auxiliary relay There is a possibility that the 52TZ will operate and lead to a mistrip.

In order to avoid the above-mentioned problems, it is necessary to always check the voltage before checking the continuity.
However, it is cumbersome to connect the voltage checker and check the voltage at each check, and then to check the continuity by connecting the continuity checker, especially a buzzer or fuse clip again. And so on. For example, if work is hurried at the time of a power outage and a voltage check is erroneously performed with a buzzer clip, a live line may be grounded and recovery may be further delayed. Also, it was cumbersome to individually carry the voltage checker and the buzzer and fuse clip, which are continuity checkers, behind a narrow switchboard.

[0008] Further, by switching the range of one tester, it may be used as a voltage checker and a continuity checker. In this case, too, when checking a large number of cables repeatedly, the range switch is forgotten. Or a short circuit, which may cause a mistrip accident or the like.

As a conventional technique for performing such a voltage check and a continuity check with a single device and preventing a continuity check for a live line, the following cable checker is known (reference: " Electric field technology ”, 1
April 996, pp. 33-35). In other words, this cable checker first performs a voltage check, and if there is no voltage, the measurement range is automatically switched to a continuity check, but if the cable has a certain voltage or more, the continuity check circuit is locked. Things.

[0010]

However, the above-mentioned prior art has the following problems. First, since the conventional checkers use a digital meter for voltage display, it was difficult to intuitively grasp the presence or absence of a voltage. Further, the digital meter does not display a value for about 0.5 to 1.0 seconds when the circuit for automatically switching the range is operating, and it is difficult to quickly grasp the presence or absence of the voltage. . Therefore, a cable checker that can quickly and intuitively grasp the presence or absence of a voltage has been desired.

In the conventional cable checker, 2
When checking continuity with one set of units, two buzzers indicating continuity confirmation
Since only one of the tables rang, it was difficult to smoothly check the conduction. For this reason, there has been a long-awaited need for a cable checker that allows easy confirmation of conduction.

Further, in the conventional checker, the power switch must be turned on during use. Therefore, the battery may be consumed by forgetting to turn off the switch, and the next use may be hindered. For this reason, a cable checker for preventing unnecessary battery consumption has been desired.

The present invention has been proposed in order to solve the above-mentioned problems of the prior art. It is an object of the present invention to provide a cable checker and a cable check method capable of quickly and intuitively grasping the presence or absence of a voltage. To provide.
Another object of the present invention is to provide a cable checker that can easily check continuity.

[0014]

In order to achieve the above object, the invention according to claim 1 comprises a voltage discriminating circuit for detecting the presence or absence of a voltage in a circuit to be measured of a cable, and a continuity of the circuit to be measured. In a cable checker having a continuity check circuit having a switch for confirming a voltage and a meter circuit for displaying a voltage detected by the voltage determination circuit on an analog meter, the presence of the voltage is detected by the voltage determination circuit. When the voltage is AC, a relay is provided for shutting off a part of the continuity check circuit and locking a continuity check function by the switch when the voltage is AC. By dividing the current from the analog meter, the full scale related to DC and AC in the display pointer of the analog meter is displayed. Wherein the shunt circuit for adjusting the Le is provided.

According to the first aspect of the present invention, the relay for cutting off a part of the continuity check circuit has a continuity check function by the continuity check switch when the presence of a voltage is detected by the voltage determination circuit. Locking is possible, and when the circuit to be measured is a live circuit, the risk of a continuity check is avoided, and a mis-strip or a short circuit accident is prevented. Further, when the voltage is AC, by shunting the AC from the analog meter, a shunt circuit for adjusting the full scale related to DC and AC in the display pointer of the analog meter is provided, The full scale of the direct current and the alternating current in the display pointer of the analog meter can be adjusted to the same amplitude, and the display can be easily understood.

According to a second aspect of the present invention, in the cable checker of the first aspect, two light-emitting diodes are provided, each of which emits light in accordance with the polarity of the current whose voltage is detected by the voltage discriminating circuit. It is characterized by.
According to the second aspect of the present invention, since the two light emitting diodes light up in accordance with the polarity of the current, it is possible to intuitively and easily confirm whether the current is DC / AC or positive / negative. . For example, light emitting diodes of different colors are turned on in accordance with whether DC is positive or negative, and both are turned on in the case of AC.

The third aspect of the present invention is the first or second aspect.
The above-mentioned cable checker is characterized in that a melody starting circuit for playing a predetermined melody when a voltage is detected by the voltage determining circuit is provided. According to the fourth aspect of the invention, when a voltage is present in the cable, a predetermined melody is played. For this reason, the presence or absence of a voltage is clearly and intuitively understood, compared to a case where the state is notified by the intermittent sound and the continuous sound of the buzzer, etc.
Safety is improved.

According to a fourth aspect of the present invention, in the cable checker according to the third aspect, an electronic switch for supplying power to the melody starting circuit in accordance with the presence or absence of a voltage detected by the voltage determining circuit; An automatic reset type switch for supplying power to the continuity check circuit is provided. According to the fourth aspect of the present invention, when a voltage is present in the cable, a predetermined sound is produced, so that the presence or absence of the voltage is clearly understood, and the safety is improved. Also, according to the result of the voltage detection, power is supplied to other necessary circuits by the electronic switch, but power is supplied to the continuity check circuit only while the automatic return type switch is pressed. For this reason, when the automatic reset type switch is released, the power is turned off at the source flow, and the battery is not consumed by forgetting to turn off the switch.

[0019]

Next, embodiments of the present invention will be specifically described with reference to the drawings. [1. Configuration of Embodiment] [1-1. Schematic configuration]

First, FIG. 1 is a diagram showing an appearance of a cable checker (hereinafter, referred to as “this device”) in the present embodiment. As shown in FIG.
And a clip CL1 for connecting to a cable, a clip CL2 for connecting to ground, and an analog meter M for displaying the voltage of the cable. Further, the case 1 has a slide switch S.D for setting the state of the apparatus when used as a set of two units. SW, push button switch PB1 for checking continuity, and push button switch PB2 for checking battery
Is provided.

In the case 1, a battery and a circuit board (not shown) are provided, and
L2, meter M, switches PB1, PB2, S. SW
Together, they constitute the following circuit. First, a circuit diagram of the present apparatus is shown in FIG. This circuit includes a voltage determination circuit 21 for determining the presence or absence of a cable voltage, and a continuity check circuit 22 for checking cable continuity. The circuit shown in FIG. 2 is a meter circuit 23 for displaying the voltage of the cable on the analog meter M.
A melody activation circuit 24 for playing a predetermined melody when the voltage of the cable is detected, a battery check circuit 25 for checking battery consumption,
Having. Next, each of the circuits 21 to 25 will be specifically described.

[1-2. Voltage discriminating circuit] The voltage discriminating circuit 21 discriminates the polarity of the voltage of the cable by the diodes D1 and D2, and uses the currents amplified by the transistors Tr1 and Tr2 to emit light from the light emitting diodes LED1 and LE.
It is configured to turn on D2 and includes the following elements.

[1-2-1. Transistors Tr1 and Tr2] The transistors Tr1 and Tr2 are light emitting diodes LED
1 (red) and LED2 (green). That is, in FIG. 3, when the terminal A is + (plus), a current flows as indicated by a path 31 shown by a solid line, so that the transistor Tr1 is turned on and the red light emitting diode LE is turned on.
D1 lights up. Conversely, when the end A is-(minus), a current flows as indicated by a path 2 indicated by a broken line, the transistor Tr2 is turned on, and the green light emitting diode LED2 is turned on.

On the other hand, in the case of AC, for example, at 50 Hz, + (plus) and-(minus) at the A end are switched 50 times per second, so that the light emitting diode LED1 and the LE
D2 actually blinks alternately, but actually looks as if both are lit as a result of the afterimage phenomenon.

Incidentally, the light emitting diode is generally 10 to
Since the light is turned on when a current of 20 mA flows, a current of 21 mA is flowed here to ensure the operation. Specifically, first, since the current amplification factor of the transistor is generally 50 to 100 times, the base current of the transistor Tr1 required for lighting the light emitting diode is

## EQU00001 ## 21 mA / 100 = 0.21 mA. This base current, as shown in FIG.
Since the current flowing between points B and B is divided from the current E1 and the current flowing between points A and B needs to be at least 10 times the base current, the current of E1 is:

## EQU00002 ## 0.21 mA.times.10 = 2.1 mA. However, if a current of this magnitude is obtained from the circuit to be measured, there is a possibility that a trouble such as the operation of the relay 64D shown in FIG. 35 may occur.
Performs amplification using transistors. For example, 2SC982
The transistor has a configuration in which two transistors are internally connected in Darlington. Here, the Darlington connection is a connection of transistors as shown in FIG. In FIG. 5, h1 and h2 are current amplification rates of individual transistors, and the current amplification rate (h1 · h2) in such a configuration reaches 5000 or more. Here, the above-described 2S is used as the transistors Tr1 and Tr2.
Although a C982 transistor is used, it is a matter of course that the amplifier circuit may be configured by combining two single transistors.

[1-2-2. Resistors R7, R8] The resistors R7, R8 limit the collector currents of the transistors Tr1, Tr2 to stabilize the operation of the transistors Tr1, Tr2. FIG. 6 shows a state where the transistor Tr1 is conducting and the light emitting diode LED1 is lit. That is, the power supply voltage E = 6.
Since 21 mA flows through the resistor R7 at 0 V, the following equation holds. Hereinafter, x to the power of y is represented as x ＾ y.

(3) (21mA × 10mA-3 × R7) + 1.4V + 2.0V = 6.0V Therefore, R7 = (6.0- (1.4 + 2.0)) / (21 × 10∧-3) = about 123.8 (Ω Therefore, for example, as the resistors R7 and R8, 120Ω
And

[1-2-3. Diodes D1 and D2] The diodes D1 and D2 operate in pairs with the resistors R3 and R4, respectively, as shown in FIG.
A circuit for determining whether (plus) or-(minus) is formed. That is, in this circuit, first, when the terminal A is + (plus), as shown in the path 1, A → R2 → R3 → D2
→ Current flows through B (path 71). At this time, since the diode D1 is in the reverse direction, no current flows, and it is similar to the absence of the diode D1. On the other hand, since the diode D2 is in the forward direction, all the current flows through the diode D2 without flowing through the resistor R4, which is similar to the case where the resistor R4 is single-stranded.

Therefore, equivalently, the state of FIG. 8 is realized, and the transistor Tr1 is turned on because the input voltage is applied, and the light emitting diode LED1 is turned on (path 8).
1) The transistor Tr2 does not operate because no input voltage is applied, and the light emitting diode LED2 does not light. When the A end is-(minus), the operation opposite to the above is performed.

[1-2-4. Resistors R2, R3, R4] As shown in FIG. 8, the resistors R2, R3 divide the input voltage applied to the terminals A, B and apply a voltage of an appropriate magnitude to the transistor Tr1. Also, the A end is-
When the value is (minus), the resistors R2 and R4 perform the same operation.

In FIG. 9, the transistor Tr1
Is 5000 times, and the current at the B end is I
Assuming B, the base current is

IB = 21 mA / 5000

= Approximately 0.004 (mA). When the current I flowing through the input AB is set to be 10 times the base current,

I = 10 × IB = 10 × 0.004 mA = 0.04 (mA) It is necessary to flow. Also, since the minimum operating voltage is set to 20V,

R2 + R3 = 20 V / I = 20 / 0.04 mA = approximately 500 (kΩ) Further, the voltage at point P is

R3 / (R2 + R3) × 20 V = 1.4 V + 2.0 V + IB · R5 = 3.4 V + 0.004 mA × 100 kΩ = 3.8 (V) That is, R3 / 500 kΩ × 20 V = 3.8 R3 = 95 (kΩ) From R2 + R3 = 500 kΩ, R2 + 95 kΩ = 500 kΩ R2 = 405 (kΩ) However, due to the influence of the resistor R5 and the internal resistance of the transistor Tr1, the actual value is finally obtained by experiments, and specifically, as follows: Become.

R2 = 510 kΩ R3 = 100 kΩ R4 = 100 kΩ [1-2-5. Resistors R5 and R6] The resistors R5 and R6 are for limiting the base current of the transistors Tr1 and Tr2. Hereinafter, the square root of X is represented by SQR (X)
In FIG. 9, the voltage at the end A is a peak value from a minimum of 20 V to a maximum of 220 V AC.

SQR (2) × 220V = 311V At that time, the theoretical voltage at point P is the minimum value,

## EQU10 ## R3 / (R2 + R3) × 20V = 100 kΩ / (510 kΩ + 100 kΩ) × 20 V = 3.27 V

R3 / (R2 + R3) × 311V = 100 kΩ / (510 kΩ + 100 kΩ) × 311V = 51.0 V On the other hand, since the voltage at the point Q is constant at 3.4 V, the resistors R5 and R6 absorb the difference voltage.

[1-3. Meter Circuit] The meter circuit 23 is a circuit for displaying the voltage of the cable on the analog meter M, and includes the following parts and elements (FIG. 2).

[1-3-1. Meter] Meter M is generally called a VU meter.
It is a simple ammeter of the moving coil type. Although the operating current is often 200 to 400 μA in full scale, a current of 250 μA is used here. That is, a high-sensitivity type such as 50 μA full scale is not suitable because it is easily affected by an induced voltage from the control cable, while a low-sensitivity type is because the connected meter itself conducts a ground fault current. , Relay 64DRy shown in FIG.
This is because there is a disadvantage that the device operates. Since the generally used relay 64DRy is set to operate at about several mA, the sensitivity of the meter is preferably 1/10 (500 μA) or less.

[1-3-2. Diode Bridge] The diode bridge DB is as follows. First, since the voltage of the control circuit is checked with respect to the ground, the voltage of the positive and negative currents is measured in the case of DC, and the voltage of the current whose polarity is repeatedly switched in the case of AC. Will be measured.
Therefore, a diode bridge is used to always swing the meter to the positive side. The diode bridge DB according to the present embodiment has a maximum operating voltage of 220 V in the present embodiment, and a peak value of

SQR (2) × 220V = approximately 311V Therefore, a device having a withstand voltage of 600V is used. In general, a diode bridge does not have a linear forward voltage-current characteristic at 1 V or less (FIG. 10), and it is difficult to swing the meter accurately. However, the minimum operating voltage in this embodiment is 24 V. Yes, and the purpose of the present embodiment is not to measure the voltage value accurately.
There is no particular problem.

[1-3-3. Volume VR1] The volume VR1 and the resistor R1 function as a voltage divider of the ammeter M, and as a whole, as shown in FIG. 11 (a diode bridge DB is omitted), is a voltmeter. Here, if the meter is caused to swing at full scale at DC 110 V, since the meter is at full scale at 250 μA, if the internal resistance 680Ω of the meter is represented by r,

[Expression 13] VR1 + R1 + r = E / I = 110V / 0.00025A = 440000Ω = 440kΩ Therefore, VR1 is set to 500 kΩ and used for full-scale adjustment of DC 110 V.

[1-3-4. Resistor R1] The resistor R1 plays a role of dividing an input voltage when an alternating current flows through a circuit of the regulator VR2 (described later) and the capacitor C1. That is, in order to keep the withstand voltage of the capacitor C1 low, about 1/10 of the input voltage is
2 and the capacitor C1 (FIG. 1
2),

(R1 + r) / (VR1 + R1 + r) = 1/10 (R1 + r) / 440 = 1/10 R1 + r = 44 kΩ Since r = 680Ω, R1 = 44−0.68 = 43.32 Therefore, R1 = 40 kΩ I do. In addition,

VR1 + R1 + r = 440 kΩ VR1 = 440−40−0.68 = 399.32 (kΩ)

[1-3-5. Volume VR2 and Capacitor C1] These are divided by direct current by dividing an alternating current.
This is for making the full scale of 10 V and the 220 V AC the same. That is, when checking the voltage of the control circuit, the most frequently handled is DC +50 V or -5.
Since the circuit is 0 V, the display is easily understood by causing the pointer to swing as much as possible in the case of DC 50 V.

To simplify this, as shown in FIG. 13, in the case of an alternating current, the current flowing through the circuit of the regulator VR2 and the capacitor C1 should be equal to the current flowing through the resistor R1 and the meter r. Therefore, if f is a frequency,

## EQU16 ## The volume VR2 and the capacitor C1 satisfying the equation of R1 + r = VR2 + 1 / 2πfC1 may be selected. However,

R1 = 40 kΩ r = 680Ω

By the way, the frequency f is 50
Hz and 60 Hz. Generally, if a meter for use in a 50 Hz area is directly used in a 60 Hz area, an error occurs in a display value. In this regard, the present apparatus may be configured to calibrate with the volume VR2 or to switch and use the capacitor C1 for 50 Hz and 60 Hz. However, in order to make such a switching operation unnecessary, it is desirable to configure as follows. That is, the value of 1 / 2πfC1 is approximately 1/1 with respect to VR2.
If set to about 0, the combined impedance is
It is considered that there is no significant difference between the case of 50 Hz and the case of 60 Hz.

Therefore, in equation (16):

[Expression 18] By substituting 1 / 2πfC1 = (1/10) · VR2,

40 + 0.68 = VR2 + (1/10) · VR2 = 1.1 × VR2 1.1 × VR2 = 40.68 VR2 = approximately 36.98 kΩ By substituting this into Expression 18, C1 is obtained.

1 / (2π × 50 × C1) = 1/10 × 36.98 × 10 ＾ 3 (Ω) C1 = 1 / (2π × 50 × 3698) = 0.86 × 10 ＾ -6 (F ) = 0.86 (μF) Therefore, assuming that C1 is 1 μF, for example, as an actual part, and the impedance of C1 is calculated, when the frequency f is 50 Hz,

1 / (2π × 50 × 1 × 10 ＾ −6) = about 3.18 × 10 ＾ 3 (Ω) = 3.18 (kΩ) When the frequency f is 60 Hz,

1 / (2π × 60 × 1 × 10 ＾ −6) = about 2.65 × 10 ＾ 3 (Ω) = 2.65 (kΩ) Here, when the value of the impedance at 50 Hz is substituted into Equation 16,

40 + 0.68 = VR2 + 3.18 VR2 = 37.5 (kΩ) For example, as an actual part, VR2 is 100 k
Use the one with Ω. This VR2 is for full-scale adjustment of AC 220V, but if this setting is used at 60 Hz, the combined impedance becomes

50 Hz: 37.5 + 3.18 = 40.68 (kΩ) 60 Hz: 37.5 + 2.65 = 40.15 (kΩ), which is only 1.3% smaller than the case of 50 Hz. Therefore, no particular problem occurs.

On the other hand, when the input voltage is V = 220 V (AC), the withstand voltage of the capacitor C 1 is as follows:

(R1 + r) / (VR1 + R1 + r) · V = (40 + 0.68) / (399.32 + 40 + 0.68) × 220 = about 0.0925 × 220 = about 20.3V Therefore, as shown in FIG.

SQR (2) × 20.3V = 28.7V Since the withstand voltage is 28.7V, a capacitor having a voltage of 50V may be used as the capacitor C1.

For example, when the AC shunt circuit as in the present embodiment is not used, as shown in FIG.
As the display scale, the DC and AC values are almost at the same position, but the position of the 50 V DC scale most frequently used is only 1/4 of the maximum swing width of the pointer. On the other hand, in the present embodiment, as shown in FIG.
It can be used in both the Hz region and the 60 Hz region.

[1-4. Melody activation circuit] The melody activation circuit plays a predetermined melody when the cable is a live line, and has the following elements (FIG. 2).

[1-4-1. Diodes D3 and D4] The diodes D3 and D4 form an OR circuit. That is, as shown in FIG.
In any case, since only one of r2 is conductive (on) in any case, even when any one of them is conductive, the transistor Tr3 is made conductive to flow the melody. Assume that diodes D3 and D4
When the transistor Tr1 is turned on and the transistor Tr2 is inactive, the wraparound circuit of the path 172 also turns on the light emitting diode LED2.

[1-4-2. Capacitor C2] The capacitor C2 is used for waveform smoothing during AC input. Unlike the case of DC input, the points A shown in FIG.
19 are as shown in FIG. 19. If the capacitor C2 is not used, the waveform at the point E is intermittent, so that the transistor Tr3 is repeatedly turned on and off. As a result, the relay X is turned on and off. The turning off is repeated (FIG. 19D). Therefore, the capacitor C2
Smoothes the waveform by the action of charging and discharging of the capacitor ("e" in FIG. 19). Regarding the capacity of the capacitor C2, if the capacity is too small, the required discharge time is too short, and the relay X causes chattering (repetition of ON / OFF),
On the other hand, if it is too large, there is a disadvantage that the melody continues to sound even when the input voltage is extinguished due to the discharge time being too long. Therefore, the capacitance of the capacitor C2 is desirably about 10 μF.

[1-4-3. Resistance R9] The resistance R9 is obtained by pulling (adjusting) the base voltage of the transistor Tr3 to the emitter voltage.
This makes it possible to set the collector current of the transistor Tr3 to 0 at normal time (when not in use). For this reason, installation of a power switch can be omitted. Note that the resistors R3 and R4 also
It has a similar role. The resistor R9 also forms a discharge circuit (FIG. 20) for the capacitor C2.

[1-4-4. Resistor R10] The resistor R10 is for controlling the base current of the transistor Tr3. When the resistance value of the resistor R10 is reduced, a large current can flow through the collector of the transistor Tr3. Here, the resistance R10 is 1 kΩ.

[1-4-5. Relay X] The relay X activates a melody circuit by one b-contact and locks the continuity check circuit by another b-contact when a voltage equal to or more than a predetermined value is applied to the coil-side input terminal. As the relay X, for example, the following ratings can be considered. Rated voltage: DC5V Number of contacts: 2a, 2b Coil resistance: 126Ω Minimum operating voltage (current): 2.46V (20mA) Minimum holding voltage (current): 1.30V (10.6mA)

Although the type and rating of the relay X can be changed as appropriate, a relay having 2 V and 2 B contacts at DC 5 V is particularly desirable. However, depending on the rating of the relay, the resistance R1
It is necessary to adjust 0 and R11.

Further, as a general property of the relay, even when the rating is 5 V as described above, the relay actually operates when 2.46 V is applied. This voltage is called the minimum operating voltage. Further, the relay that has operated once keeps operating up to a predetermined voltage even if the voltage is lowered from the minimum operating voltage. This voltage is called the minimum holding voltage, and is the minimum operating voltage (2.46).
V) (about 1.30 V).

In the present embodiment, as shown in FIG.
Assuming the minimum holding voltage of the relay, contact b and resistor R1
1 is used to prevent the consumption of the battery during use.
That is, in FIG. 21, when the transistor Tr3 is not conducting (on), the contact b of the relay X is closed, and the resistor R11 is short-circuited by the contact b.
Therefore, the rated voltage of 5 V is applied to the relay X at the moment when the transistor Tr3 is turned on. Then, the contact b is opened at the moment when the relay is turned on.
Are connected, and while the operation of the relay X is maintained, the current value is reduced to about half of the value at the time of starting. In the present embodiment, the current value at the time of startup is 39.6 mA, while the current value during holding is 20.9 mA.

Here, the current for holding the operation of the relay X is set to be much larger than the original minimum holding current (10.6 mA).
Is stable even if the voltage drops from the rated 6 V to, for example, 3.6 V, which is 60%, due to wear. When the battery is further consumed and drops to 3.6 V or less, the relay X enters a state of chattering (repeatedly turning on and off). To prevent this, a battery check circuit is used.

[1-4-6. Resistance R11] As described above, the resistance R11 is for limiting the holding current of the relay X by being combined with the contact b of the relay X. Here, the resistance R11 is set to 120Ω. In addition, the current (20.9 m
A) is used as a power source for starting the melody IC. In addition, as the melody IC 26, 1.5 V or more and 0.5 m
A ready-made product that operates at about A can be used (FIG. 2).
2).

[1-4-7. Diode D5] The diode D5 is for absorbing the back electromotive force when the relay X is off.

[1-5. Continuity Check Circuit] The continuity check circuit 22 is a circuit for confirming cable continuity when the voltage is “absent”, and has the following components (FIG. 2).

[1-5-1. Fuse F] The fuse F is a fuse that operates when the voltage circuit is checked while the push button PB1 is pressed by mistake.
It also has a role of protecting the continuity check circuit, but its main purpose is to promptly shut off the circuit under test.

[1-5-2. Push Button Switch PB1] There are generally various types of switches, for example, a snap type, a rotary type, a slide type, and a push button type which is turned on when pressed once and turned off when pressed again. is there. In the present embodiment, an automatic reset type push button switch which is turned on only while the switch is being pressed is used, so that the switch need only be pressed while the switch is being used, thereby preventing forgetting to switch off.

[1-5-3. Slide switch S. SW] slide switch S. SW is a short changeover switch for changing the polarity of the battery BAT2. As a type of the switch, a desired type such as a snap type or a rotary type may be selected. Also, always decided 2
If one set is used, the battery B must be
The polarity of AT2 is reversed from the beginning, one for A-end,
By setting the other for the B-end, the slide switch S. SW can also be omitted (FIG. 23).
In this way, the circuit is simplified, the number of components is reduced, and the possibility of failure is reduced. In the present embodiment, when there are three or more devices, each of the slide switches S. and S. is used so that any combination can be used. S
By providing W, it is possible to switch to either A or B.

[1-5-4. Buzzer BZ] The buzzer BZ is for sounding the presence or absence of continuity by sounding when the continuity is checked, by sounding the presence of continuity. In addition, in order to indicate conduction “with” or “without”, it is conceivable to use light such as a light emitting diode at the same time as sound, but in this embodiment, the light emitting diode is used in the voltage checker unit. Therefore, in order to avoid confusion, it is expressed only by a buzzer. Further, if the melody and the battery of the voltage checker unit are used to generate sound, the number of components can be reduced. However, a buzzer is used to avoid confusion with the melody at the time of voltage check and to make a clear distinction.

[1-5-5. Battery BAT2] The battery BAT2 is a power supply for sounding the buzzer BZ, and is independent of a voltage check circuit.

[1-6. Battery Check Circuit] The battery check circuit is a circuit for checking the consumption of the battery BAT1, and has the following components (FIG. 2).

[1-6-1. Push Button Switch PB2] The push button switch PB2 has a double connection. One of the contacts measures the voltage of the battery BAT1, and the other contact connects the resistor R12 to the battery BAT1 as a dummy load (simulated load). It is for connecting in parallel. As this push button switch PB2, an automatic reset type switch is used. By pressing the push button switch PB2, a circuit as shown in FIG. 24 can be constructed by simplification.
The basic circuit of the battery check as shown in FIG.

[1-6-2. Resistance R12] The resistance R12 is a dummy load (simulated load) at the time of battery check.

[2. Operation and Effect of Embodiment] The present embodiment having the above configuration has the following operation. That is, by using the present apparatus as a pair, the voltage check and the continuity check can be continuously performed. First, prior to use, one slide switch is set to “A” and the other slide switch is set to “B”. Next, one of the clips of each device is connected to both ends of the cable, and the other of the clips of each device is connected to the ground terminal (FIG. 26).

[2-1. Voltage Check] In a state where the push button switch PB1 is not pressed, each device functions as a voltage checker, and by the operation of the voltage discriminating circuit 21, the light emitting diodes LED1 and LED1 correspond to the polarity of the current.
The LED 2 is turned on, and the voltage is immediately displayed on the analog meter M by the operation of the meter circuit 23. For this reason, the presence or absence of a voltage can be visually and intuitively and quickly confirmed, and the safety and reliability of the operation are improved. In the voltage check of the cable, the main purpose is to determine the presence or absence of a voltage. Therefore, it is not necessary to use a digital meter to ensure display accuracy.

The full scale of direct current and alternating current in the display pointer of the analog meter M is adjusted to the same amplitude by the meter circuit 23, so that the display can be easily understood. Further, in the analog meter M of the present apparatus, since the pointer of the meter always swings in the forward direction due to the operation of the meter circuit 23 and there is no reverse swing, it is easy to understand the numerical value. In addition, since the light emitting diode is illuminated in red when the direct current is positive, green when the direct current is negative, and both in the case of alternating current, the polarity can be easily determined visually.

When the cable connected to the present apparatus is a live line, the transistor Tr3 is turned on, so that a current starts flowing through the path 271 in FIG. At the time when this current starts to flow, each contact of the relay X is turned on because it is connected to the terminal b, but as a result of the current passing through the coil-side input terminal of the relay X, each contact is turned off. .

As a result, first, the continuity check circuit 2
In 2, the continuity check function is locked by shutting off the circuit, and the danger of conducting a continuity check on a live line is avoided. In this state, the push button switch PB
Even if 1 is pressed, the continuity check cannot be performed. As described above, according to the present embodiment, the continuity check can be performed only when the voltage is “absent”, so that a trouble such as a mistrip accident due to a ground fault or a short circuit does not occur.

In the melody starting circuit 24,
Current flows through path 272 and, according to Ohm's law,
On both ends of the resistor R11

E = I · R11 (approximately 2.2 V) is generated, and this voltage causes the melody IC 26 to sound. By playing a predetermined melody in this way (FIG. 28), attention is called through hearing, and work safety is improved. In particular, compared to a case where the presence or absence of a voltage is notified by whether the buzzer is continuous or intermittent, the presence of the voltage is effectively notified by the characteristic sound of the melody, thereby improving work safety.

[2-2. Continuity Check] When the voltage is “none”, the hand of the analog meter M does not swing, the light emitting diode does not turn on, and no melody flows.
When the voltage of the cable is "nothing", by pressing the push button switch PB1 (FIG. 29), a circuit is formed by the continuity check circuit 22 of each device, the cable and the ground, and the buzzer BZ of each device is simultaneously turned on. Sound
Continuity can be confirmed.

That is, when the circuit is turned on by the cable W being checked, the continuity check circuit 22 of each device in a pair constitutes the circuit shown in FIG. Sound.
The conduction path of the current at this time is shown by a broken line in FIG. As described above, in the present embodiment, the buzzer BZ sounds at both the devices connected to both ends of the cable, so that the workers at both ends simultaneously check the continuity without having to communicate with each other via a telephone device or the like. Work efficiency is improved.
As a result, it is not necessary to provide a communication function in the cable checker, so that the cable checker is reduced in size and weight, and is easily transported and stored.

It is assumed that the push button switch PB
Even if this device is connected to the AC current cable and the ground while pressing 1 from the beginning, the fuse F of the continuity check circuit 22 is activated and the circuit is immediately cut off, so that a fault such as a mistrip due to a ground fault current may occur. It does not occur.

Further, when only one device is used alone, the continuity check can be performed by connecting the device to one end of a cable and connecting a conventional fuse clip to the other end. . In this case, the slide switch S. SW may be set to either “A” or “B”.

[2-3. Battery Check] In the present device, a battery check can be performed as follows. First, to check the battery BAT1, a push button switch PB2 for battery check is pressed. At this time, if the pointer of the meter is within the predetermined range, the battery BAT1 has not been consumed. The path through which the current is conducted when the push button switch PB2 is pressed is indicated by a thick line in FIG.

This path equivalently constitutes the circuits shown in FIGS. 24 and 25. The principle of the battery check uses a phenomenon that the internal resistance of the battery becomes larger as it is consumed. That is, when the battery is exhausted, the internal resistance increases, and the voltage at both ends of the resistor R12, which is a simulated load, decreases because the amount of current decreases. This voltage is measured with a voltmeter M
The battery consumption can be determined by comparing with the level previously written on the display panel of (1). The resistance r in FIG. 25 conceptually shows the internal resistance of the battery itself. In this check, as shown in FIG.
, The green LED 2 is turned on and a melody is played. For this reason, the operation check of the present apparatus is also possible.

In order to check the battery BAT2 of the continuity check circuit 22, the slide switch S. S
Set W to "A" or "B", connect the two clips together, and press the continuity check push button switch PB1. If the buzzer for confirming conduction sounds sufficiently clearly when pressed, the battery BAT2 is not depleted.

In the present embodiment, the power is supplied to other necessary circuits by the electronic switch according to the result of the voltage detection. However, the electronic switch is a push button switch which is an automatic reset type switch. Power is supplied only while PB1 is pressed. For this reason, when the push button switch PB1 is released, the power is turned off at the source flow, and the battery is not consumed due to forgetting to turn off the switch.

[3. Other Embodiments] The present invention is not limited to the above-described embodiment, but includes other embodiments as exemplified below. For example, details such as a specific element configuration and a rating of each circuit such as a circuit for performing a voltage check and a continuity check and a shunt circuit can be freely changed.
Further, the specific lighting mode of the light emitting diode according to the polarity is arbitrary, and for example, plus of direct current, minus of direct current, and alternating current may be indicated by one light emitting diode each. Further, it is not always necessary to notify the presence of the voltage by a melody, but may be notified by a buzzer or a light emitting element. Also, the continuity check may be notified by a melody or a light emitting element instead of the buzzer, or may be notified by only one of the pair of the present apparatus. Also, a shunt circuit for the meter, a light emitting diode indicating polarity, a fourth circuit for playing a melody, and the like are not essential and may be omitted.

[0079]

As described above, according to the present invention,
Since a cable checker and a cable check method capable of easily and quickly grasping the presence or absence of a voltage are provided, work reliability and safety are improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an appearance of a cable checker according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a cable checker according to an embodiment of the present invention.

FIG. 3 is a partial circuit diagram showing a current conduction path in the embodiment of the present invention.

FIG. 4 is a circuit diagram showing current amplification by a transistor in the embodiment of the present invention.

FIG. 5 is a circuit diagram showing current amplification by Darlington connection of transistors in the embodiment of the present invention.

FIG. 6 is a circuit diagram showing a state of a transistor Tr1 when the light emitting diode LED1 is turned on in the embodiment of the present invention.

FIG. 7 is a partial circuit diagram showing a current conduction path in the embodiment of the present invention.

FIG. 8 is a partial circuit diagram equivalently showing a current conduction path in the embodiment of the present invention.

FIG. 9 is a circuit diagram showing current amplification by a transistor in the embodiment of the present invention.

FIG. 10 is a diagram showing voltage-current characteristics of a diode in the embodiment of the present invention.

FIG. 11 is a circuit diagram conceptually showing a connection state of a voltmeter in the embodiment of the present invention.

FIG. 12 is a conceptual diagram showing a division of an input voltage in the embodiment of the present invention.

FIG. 13 is a circuit diagram conceptually showing division of an input voltage in the embodiment of the present invention.

FIG. 14 is a diagram showing a relationship between a peak value of an alternating current and an effective value in the embodiment of the present invention.

FIG. 15 is a diagram showing a display example of a voltmeter when an AC shunt circuit is not used in the embodiment of the present invention.

FIG. 16 is a diagram showing a display example of a voltmeter when an AC shunt circuit is used in the embodiment of the present invention.

FIG. 17 shows a diode D according to an embodiment of the present invention.
FIG. 3 is a diagram showing a state in which the light emitting diode LED2 malfunctions when D4 is not used.

FIG. 18 is a partial circuit diagram showing points related to a waveform at the time of AC input in the embodiment of the present invention.

FIG. 19 is a diagram showing waveforms at respective points shown in FIG. 18 in the embodiment of the present invention.

FIG. 20 is a diagram showing a capacitor C according to the embodiment of the present invention;
2 is a circuit diagram conceptually showing the discharge of No. 2.

FIG. 21 is a circuit diagram conceptually showing a relationship between a relay X and a contact in the embodiment of the present invention.

FIG. 22 is a circuit diagram conceptually showing a state in which a voltage for a melody IC is obtained from a current flowing through a resistor R11 in the embodiment of the present invention.

FIG. 23 is a partial circuit diagram showing another configuration example of the continuity check unit in the embodiment of the present invention.

FIG. 24 is a circuit diagram conceptually showing a simplified circuit configured at the time of battery check in the embodiment of the present invention.

FIG. 25 is a circuit diagram conceptually showing a basic principle of battery check in the embodiment of the present invention.

FIG. 26 is a diagram showing a voltage check state in the embodiment of the present invention.

FIG. 27 is a partial circuit diagram showing a conduction path of a current flowing through a relay X in the embodiment of the present invention.

FIG. 28 is a diagram showing a voltage “present” in the embodiment of the present invention;
The figure which shows the state where a melody is played in the case of.

FIG. 29 is a view showing a voltage “None” in the embodiment of the present invention;
The figure which shows the state which performs a continuity check by pushing the push button switch PB2 in the case of.

FIG. 30 is a partial circuit diagram showing a circuit configured by two cable checkers at the time of a continuity check in the embodiment of the present invention.

FIG. 31 is a circuit diagram conceptually showing a circuit configured to perform a battery check by pressing a push button switch PB2 in the embodiment of the present invention.

FIG. 32 is a diagram showing a state of voltage check according to the related art.

FIG. 33 is a diagram showing a state of a continuity check according to a conventional technique.

FIG. 34 is a diagram showing a state in which a ground fault occurs in the related art.

FIG. 35 is a diagram illustrating an example of a control circuit of a substation.

[Explanation of symbols]

 1: Case CL: Clip LED: Light emitting diode M: Analog meter (voltmeter) PB: Push button switch SW ... Slide switch 21 ... Voltage discrimination circuit 22 ... Continuity check circuit 23 ... Meter circuit 24 ... Melody start circuit 25 ... Battery check circuit 26 ... Melody IC power supply BAT ... Battery C ... Capacitor D ... Diode DB ... Diode bridge F ... Fuse Tr ... Transistor VR ... Volume R ... Resistance X ... Relay

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-208867 (JP, A) JP-A-3-18766 (JP, A) JP-A-52-96579 (JP, A) JP-A-7-97 330131 (JP, A) JP-A-9-113561 (JP, A) Motoaki Kojima, Ryuji Kobayashi, Nao Isaji, Hiroshi Inoue, Development of Control Cable Checker, Electric Field Technology, Japan, April 1996, 33- 35 (58) Field surveyed (Int.Cl. ⁷ , DB name) G01R 31/02 G01R 19/155 H02G 1/02 H02G 1/06

Claims (4)

(57) [Claims] 1. A voltage discriminating circuit for detecting the presence or absence of a voltage of a circuit to be measured of a cable, a continuity check circuit having a switch for confirming the continuity of the circuit to be measured, And a meter circuit for displaying the measured voltage on an analog meter.If the voltage discriminating circuit detects the presence of the voltage, a part of the continuity check circuit is shut off, and A relay for locking a continuity check function is provided, and in the meter circuit, when the voltage is AC, the AC is shunted from the analog meter to DC and AC in the display pointer of the analog meter. A shunt circuit for adjusting the full scale is provided. Bull checker. 2. The cable checker according to claim 1, further comprising two light-emitting diodes, each of which emits light in accordance with the polarity of the current whose voltage is detected by said voltage discriminating circuit. 3. The cable checker according to claim 1, further comprising a melody activation circuit for playing a predetermined melody when a voltage is detected by the voltage determination circuit. 4. An electronic switch for supplying power to the melody activation circuit according to the presence or absence of a voltage detected by the voltage discrimination circuit, and an automatic reset for supplying power to the continuity check circuit. The cable checker according to claim 3, further comprising a mold switch.