JPH0416749B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention consists of two grips connected by a cable and provided with a contact tape and each containing a high resistance series resistor connected after the contact tape, One of these grips has a voltage range (e.g. 6, 12, 24, 50,
110, 220, 380, 660 V) and an oscillator capable of driving the optical display element of the display step assigned to the display step and an optionally provided acoustic signal generator and an input current limited by both series resistors. a buffer amplifier which amplifies the voltage and switches on the built-in battery and allows step display of the voltage under test and possibly its polarity as well as switching on of the acoustic signal generator by means of the display current from the battery. and a test device for its polarity display and continuity test.

Such a test device is commercially available under the name "Weidmuller UlT" and is described in the Weidmuller catalog "U1T Sicherheix X7". This catalog is from the 1980 Hannover-Messe
It was distributed to the public for the first time (see also the magazine “etz”, Vol. 102 (1981), No. 14, p. 747).

This known test device displays the voltage to be tested within the above voltage range (excluding 660V) in steps. The series resistors connected after the contact tapes housed in both grips are each 5MΩ.
, or a total resistance of 10 MΩ. A buffer amplifier separates the current flowing due to the voltage under test (test current) from the current flowing through the display element for step display of the voltage under test (display current). A test current generated by the voltage under test and limited by both series resistors is applied to the buffer amplifier. The display current flowing through the display element is supplied from a battery (12V) built into the test equipment, and is switched on by a transistor in a buffer amplifier.

A known test device includes a signal generator as described in German Patent Application No. 3013788 (identical to European Patent Application No. 0038043) of April 10, 1980. This signal generator (buzzer) includes a piezoceramic plate with three electrodes. An excitation voltage is applied to the two excitation electrodes, and a generated signal is acoustically extracted at the third electrode (return electrode) and applied to the input side of the amplifier via a resistor. An audio frequency signal generator with electro-acoustic feedback is thus constructed, the fundamental frequency of which is determined by the vibration parameters of the piezoceramic plate. A coil connected to this signal generator serves to increase the intensity of the sound.

In the known test device, the individual display steps are
divided into two groups. The display step for displaying the test voltage of 6V or more and less than 12V also serves to display the polarity of the DC voltage. In the case of AC voltage, both the light emitting diode for negative polarity display and the light emitting diode for positive polarity display emit light at the same time.

12V or more, less than 24V; display steps for voltage ranges of 24V or more, less than 50V and 50V or more, less than 110V constitute one cascade circuit, and 110V
220V or more, less than 220V; 220V or more, less than 380V and
The display step for voltage ranges above 380V constitutes another cascade circuit.

Voltage dividers, transistors and light-emitting diodes are included in these cascade circuits for voltage indication as described in German Patent Application No. 2846675 (U.S. Patent Application No.
4301407 and European Patent Application No. 0011711). In this case, the individual voltage dividing points of the voltage divider consisting of a plurality of resistors are connected to the base of the transistor associated with each display step,
The emitters of these transistors are connected to the emitters of adjacent transistors via a light display element configured as a light emitting diode, and the collectors of these transistors are collectively connected to a common voltage source.

The known test device has one pushbutton switch, in which the test device serves as a voltage test. When this pushbutton switch is switched to the operating position, it is
2,756,830 (see also FIGS. 7 and 8 of U.S. Pat. No. 4,210,862), the battery is switched on when placed in a case, so that the battery is switched on when the conductor under test is present between the contact tapes. can be tested for continuity. Furthermore, when both contact tapes are brought into direct contact with each other, the testing device can be inspected for the health of the battery (rated voltage is 12V), signal generator, and polarity display element. Self-checks regarding the soundness of other functions are not possible with known test equipment.

Test devices of the type mentioned at the outset, i.e. high-resistance test devices consisting of two grips, require, firstly, the safety of the user of the test device and, secondly, a unique marking and ease of handling. For this to happen, a number of requirements must be met, such as:

(1) The internal resistance of the test device shall be sufficiently high (500 kΩ or more) so that it is safe for the user to touch one of the contact tapes.
For test equipment with an internal resistance of 500kΩ or more,
When the AC voltage to ground is 220 V, the advantage is that it is safe for the user to touch one contact tape while the other contact tape is energized (touch safety).

(2) If the internal resistance is increased, the test current becomes minute, but the presence of voltage can be clearly and clearly displayed regardless of this. The high internal resistance ensures that there are almost no measurement errors even when the voltage source has high resistance, and also guarantees the contact safety listed in (1).

(3) Since the internal resistance of the test equipment is high, a voltage source separate from the voltage to be tested must be provided for the front element, that is, the test current itself must not be used as the display current.

(4) Resistors with high internal resistance and, in some cases, high withstand voltage, are used so that even if a peak voltage occurs in the circuit under test, the user will not be endangered by dielectric breakdown.

(5) High-resistance series resistors are placed in both the grip containing the display element and other grips to ensure the safety of the user even if the cable connecting both grips breaks for some reason. What can be guaranteed.

(6) Display with sufficiently bright light and sufficiently loud sound.

(7) Be safe against possible erroneous operation.
As mentioned in (1) above, an erroneous operation may occur when a user contacts one contact tape while voltage is being applied to the other contact tape. Even in such a case, as described above, the internal resistance of the test device must be high so as to maintain the safety of the user. Furthermore, an erroneous operation may occur when a push button switch for continuity testing or self-inspection is pressed while a high voltage (eg, power distribution voltage) is being applied to the contact tape. Even in such a case, it must be possible to unambiguously display the applied voltage without posing any danger to the test equipment or the user.

(8) Test equipment with a built-in battery must be capable of self-checking the battery voltage.

(9) In addition to self-checking the battery voltage, it is also possible to check the health of the polarity display element and the voltage display element corresponding to the battery voltage by bringing both contact tapes into direct contact with each other in continuity test mode.

(10) The battery is automatically switched on to avoid the risk of the user forgetting to switch it on and using the test equipment.

(11) It shall be possible to check the functionality of each display step before or during the voltage test.

(12) In addition to checking the display function (light step display and sound signal generation), it is also possible to check the integrity of the cable connecting both grips and the integrity of the avoidance in the test grip without display function. thing.

(13) It is possible to display another voltage range, for example 660V, above the voltage range of 380V.

(14) It must be possible to temporarily lower the high (600kΩ or more) input internal resistance.

From the specifications of British Patent No. 1562578, US Patent No. 4210862 and German Patent No. 2734833, etc., in a low resistance test device for voltage and continuity testing, voltage testing in the rest device or continuity testing in the operating position It is known to connect a Zena diode in parallel with a pushbutton switch to enable Safety against is guaranteed.

In addition, among the above requirements (1) to (4) and
(8) to (10) are patent applications of the Federal Republic of Germany.
This is also satisfied by the test device in the form of a screwdriver, as described in document No. 3004734. but,
This test device is monopolar, not suitable for step display, and does not meet other requirements.

The above and known test equipment meet the requirements (1) above.
I am only satisfied with (10). In other words, it is impossible to satisfy requirement (13) (adding a display step above the voltage range of 380V).
Also, it is not suitable to satisfy requirements (11), (12), and (14).

The aim of the invention is to improve a test device of the type mentioned at the outset in such a way that it is able to meet all of the above requirements.

According to the invention, this purpose is achieved by providing the test device mentioned at the beginning, (a) a step-up circuit that is supplied with power by the oscillator and serves to increase the oscillator voltage limited by the battery; An energy storage device, in particular in the form of a capacitor, is provided which is connected via an element to the output side of the booster circuit and which is charged by the output voltage of the booster circuit while this switching element is in the rest position. (c) The switching element, which is in the rest position during charging of the energy storage device, transfers the charge present in the energy storage device to the input side of the buffer amplifier, thereby sequentially verifying the integrity of all display functions of the test device. (d) The display current that the oscillator gives to the display element of the voltage under test within the upper voltage range (110 V or more) also falls within the lower voltage measurement range (6 V or more, less than 110 V). The display current applied to the display element of the voltage under test is also connected to the base of a transistor that switches (that is, chops) intermittently for a short period of time. A switching element is provided, and with this switching element switched to the operating position, a continuity test is performed on the conductor to be tested, if present, by switching on the battery between the two contact tapes;
Or, if both contact tapes are brought into direct contact with each other, inspection of the test equipment for the health of the battery, acoustic signal generator, optical display element for polarity indication, and optical display element for voltage indication corresponding to the battery voltage, and the energy storage device. This is achieved by a test device for displaying the voltage and its polarity and for continuity testing, characterized in that the charging of the capacitor within is carried out.

One preferred embodiment of the test device according to the present invention is as follows: (a) Two high-resistance, high-withstand-voltage series resistors are connected in front of a buffer amplifier serving as an input circuit, one of which is Housed in one grip and the other separated by a shielded cable, both series resistors limit the current produced by the voltage under test and A buffer amplifier is provided that includes an emitter follower and an input voltage divider, the transistor being rendered conductive via a full-wave rectifier circuit formed by the transistor and a Zener diode depending on the polarity of the voltage under test. Therefore, depending on the polarity, the polarity display transistor becomes conductive, and the current circuit of the optical display element for positive polarity display or the optical display element for negative polarity display, or in the case of alternating current voltage, the current circuit of both optical display elements. is formed, and at the same time, as the polarity display transistor becomes conductive, the base of the battery circuit switching transistor obtains a potential difference with respect to the positive potential of the battery, and the battery circuit is switched on, causing the polarity display light display element to emit light. (b) The oscillator is composed of an oscillation transistor, a resistor, an inductance, and an acoustic signal generator consisting of a three-electrode ceramic resonator as is well known, and (c) the voltage is boosted. The circuit is a voltage amplification circuit (Villard type) consisting of four diodes, three coupling capacitors, and one inductance, and is supplied with power via an oscillator, and (d) the energy storage device functions as a capacitor and peak value rectifier. It consists of a diode and a switching element that interconnects these capacitors and diodes in the rest position, and the voltage pulse from the booster circuit is stored in the capacitor through peak value rectification, so that the capacitor is charged to the peak value of the voltage pulse. (e) A protection diode and a current control resistor are provided in the connection path between the operation position side terminal of the switching element of the energy storage device and one input terminal of the buffer amplifier.

A further preferred embodiment of the test device according to the invention is characterized in that the voltage display circuit for step displaying the individual voltage ranges is divided into two voltage display cascade circuits which are supplied with mutually separate display currents, The cascade circuit for the side voltage range (above 6V, below 110V) is powered from the battery via the switching transistor, the cascade circuit for the top voltage range (above 110V) is powered by the boost circuit, and both cascade circuits Therefore, it is characterized by being intermittently opened and closed (ie, chopped) at the frequency of the oscillator.

In addition to the advantages obtained with known test devices, the test device according to the invention has the advantage that above 380V, another voltage range, for example 660V, is displayed. Furthermore, as a particular advantage, the test device according to the invention makes it possible to check the functionality of all display steps before or during the voltage test. For example, assume that during a voltage test, display elements of all display steps below 220V emit light, and display elements of 380V and display steps do not emit light. In this case, in order to confirm that 380V or 66V is not applied, it is sufficient to switch the opening/closing element S2 to the operating position and confirm that the display elements for displaying 380V and 660V emit light. That is, if the opening/closing element S2 is switched to the operating position,
These display elements should emit light as the energy storage device discharges and the discharge current is amplified by the buffer amplifier to switch on the display elements for the 380V and 660V displays. If 380V and
If one or both of the display elements for 660V display does not emit light, that display element is malfunctioning.
In other words, it is known that the voltage to be displayed by the display element may actually be applied.

In this way, with the test device according to the invention, the possibility of erroneous operation and erroneous display is completely avoided.

Further, in the test device according to the present invention, the internal resistance of the test device can be temporarily lowered so that it can be determined whether the voltage source is low resistance or high resistance during a voltage test.

In general, it is necessary to avoid measurement errors even when the circuit under test has high resistance, and to prevent the user from touching one contact tape while a high voltage is applied to the other. The internal resistance of the test device must be of a sufficiently high value so that
It is selected to be 600kΩ or more. Input internal resistance
If it is 660 kΩ, the relationship between the applied voltage and the current flowing therefrom is 110 220 380 660 [V _eff ] 0.17 0.33 0.58 1 [mA _eff ], so the above contact safety is maintained.

On the other hand, when the test equipment is used, for example, to test opening/closing cubicles or the wiring of large-scale equipment, the internal resistance of the test equipment is high, so that the test equipment is lowered by the voltage under test due to electrostatic induction or electromagnetic induction. Problems can arise in that they are sensitive to voltage sources other than the voltage source.

Whether the internal resistance of the voltage source is high or low can be determined by the presence or absence of a difference between the display voltage when the internal resistance of the test device is high and the display voltage when it is low, as will be explained in detail later. In making this discrimination, it is desirable that the internal resistance of the test device is temporarily lowered and then raised again after a period of time necessary for the discrimination.

In one embodiment of the invention, the entire circuit in one grip and a high resistance series resistor in both grips are connected to 200Ω and 5kΩ in order to temporarily reduce the high internal resistance. A PTC resistor is selectively switchable in parallel and has a rated resistance R _N between 1 and 2 and guarantees a self-heating time constant (deactivation time t _aB ) of at least 1 second. Further detailed embodiments in this case are given in claims 6 to 8.

Thereby, a test device with a high internal resistance can be selectively connected in parallel, for example by actuation of a push button, with a low resistance, for example a resistance of 2 to 10 kΩ.

Lowering the internal resistance increases the power consumption of the test equipment. For example, if the applied voltage is 500V and the internal resistance is 4kΩ, the power consumption will be 63W. This creates a problem in that the temperature inside the test device, ie, the grip containing the circuit, increases. It is also possible to connect a reactance in parallel instead of a resistor, but for safety reasons, the use of reactance is not allowed by the VDE standard.

Using a PTC resistor according to the invention avoids the problem of temperature rise, since the resistance automatically increases after a certain time due to self-heating, limiting the current and thus also the power.

The characteristics of PTC resistors, such as the rated resistance value R _N and self-heating time constant t _aB, are determined by the German standard VDE44080 (1976
(December 2015).

In order to appropriately set the time constant of the self-heating process,
It is advantageous to connect in series with the PTC resistor a resistor having a constant resistance, ie a resistance value which is virtually independent of temperature. As a result, power is distributed between the PTC resistor and the constant resistor at the moment of switch-on,
You can change the time it takes for the PTC resistor to self-heat and become highly resistant and reduce the current.

The time constant of the self-heating process is influenced by the volume of the PTC resistor. To obtain the desired time constant, the PTC resistor must be relatively large, eg, 10 mm in diameter and 20 mm thick.

Small volume (for example, 5 mm in diameter and 1 mm in thickness)
Commercially available PTC resistors are cheap and of good quality, but they build up a high resistance so quickly (within a few milliseconds) that the user has not had enough time to determine whether the internal resistance of the voltage source is high or low. I can't do it. In an advantageous embodiment of the invention, by connecting a constant resistor in series with the PTC resistor, the time constant of the self-heating process can be set to give the user a reading time of several seconds.

In order to further reduce the value of a load resistor consisting only of a PTC resistor or a load resistor in which a PTC resistor and a constant resistor are connected in series, several such load resistors may be connected in parallel.

In one preferred embodiment of the invention, if the internal resistance is 600 or 660 kΩ, the rated resistance (R _N )
A PTC resistor of 1.5 kΩ and at least one constant resistor connected in series for a total resistance of 12 kΩ is used.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

In FIG. 1, grip 1 and grip 2 are connected by a cable 3. Grip 1 has a contact tape 4 and grip 2 has a contact tape 5. In FIG. 3, grips 1 and 2 are shown within a dashed box. The cable 3 is provided with a shield 6.

Grip 1 contains only a high-resistance series resistor R30 connected after contact tape 4 and will be referred to below as test grip 1. On the other hand,
The grip 2 with the contact tape 5 contains in its interior a high-resistance series resistor R0 and the overall circuit 18 and is also provided with display elements LED1 to LED9 and two pushbutton switches S1 and S2, as follows: Let's call it display grip 2. The display grip 2 further includes a battery B1.
Contains case G containing . This case is described in German Patent No. 2756830 (see also US Pat. No. 4,210,862).

Both the test grip 1 and the display grip 2 are provided with collars 7 and 8 in accordance with the specifications of the test equipment.
These collars are intended to prevent the user of the test equipment from coming into contact with the circuit under test. The recess 9 of the display grip 2 is provided at a position where the user can easily view the display while grasping the display grip with this recess.

The pushbuttons of the switches S1 and S2 are arranged at positions where they can be easily operated with the thumb when the display grip 2 is grasped with the right hand. In addition, the display element
LED1 to LED9 are on the surface of display grip 2,
It is placed so that it is not covered by the fingers or the balls of the fingers.

The display grip 2 is shown in its wide side in FIG. The display grip 2 is flat and its thickness is only about 1/3 of its width.

The test grip 1 may be constructed as a round bar (FIG. 1), or, like the display grip 2, may be flat, especially if it incorporates components according to the circuit of FIG.

FIG. 2 shows a block circuit diagram of the test device, in which the contact tapes 4 and 5 forming the inputs are each connected to a buffer amplifier D via one high resistance series resistor R30 and R0. The buffer amplifier block also includes circuitry for polarity and lowest voltage range indication.

Series resistor with high resistance caused by the voltage under test
The current limited by R30 and R0 is amplified by a buffer amplifier to switch on battery circuit B and provide polarity and minimum voltage range indication. Buffer amplifier D is connected to voltage display cascade circuits E and F, and battery circuit B is connected to voltage display cascade circuit E.
and an oscillator C (possibly including an acoustic signal generator). Oscillator C supplies power to booster circuit A1. From the booster circuit A1, the energy storage device A2 is charged while the intermediate switch S2 is in the rest position shown in FIG.

When the switch S2 is switched from the rest position to the operating position, the charge stored in the energy storage device A2 is applied to the input of the buffer amplifier D via the diode D14. As a result, a current flows at the input of the buffer amplifier D that is greater than the current caused by the maximum value voltage that the test device is to display, so that all display steps illuminate and disappear one after another as the discharge current decays.

Circuit portion A3 includes switch S1. Switch S1 is a zener diode in the rest position shown.
It bridges D18. When switch S1 is switched from the rest position to the operating position, battery circuit B is switched on. In this state, both contact step 4
If a conductor to be tested is present between The test equipment is inspected for the health of the optical display element for voltage display corresponding to the element and battery voltage, and the capacitor C1 in the energy storage device is charged. By returning switch S1 from the operating position to the rest position and then switching switch S2 from the rest position to the operating position, all display steps are again checked for health. It is an important advantage of the test device according to the invention that a complete self-check can be carried out in this way.

FIG. 3 shows the overall circuit of a preferred embodiment of the test device according to the invention. A test grip 1 and a display grip 2 are each shown within a dashed box, and a cable 3 with a shield 6
are connected to each other by. The circuits of the display grip 2 are divided into partial circuits A to F shown within the dashed lines. Subcircuit A is further divided into three subcircuits A1, A2 and A3 in FIG.

High-resistance and high-withstand series resistors R30 and B0 are connected as input circuits after the contact tape 4 of the test grip 1 and after the contact tape 5 of the display grip 2, respectively.

The current produced by the voltage under test is limited by high resistance series resistors R30 and R0. This current is applied to buffer amplifier D. Buffer amplifier D includes transistors T1 and T2 connected as emitter followers. A current limited by high-resistance series resistors R30 and R0 is applied to these emitter followers via input voltage divider resistors R1 and R2 or R3 and R4, so that depending on the polarity of the voltage under test, transistors T1 or
T2 conducts through a full-wave rectifier circuit consisting of transistors T1 and T2 and Zena diodes D1 and D2.

As a result, transistor T3 or T4 becomes conductive depending on the polarity of the voltage to be tested, and the current circuit of +6V display light emitting diode LED2 or -6V display light emitting diode LED1, or for AC voltage, the current circuit of both light emitting diodes. At the same time, as the transistor T3 or T4 becomes conductive, the base of the battery circuit switching transistor T6 obtains a potential difference with respect to the positive potential of the battery B1, so that the battery circuit B is switched on, and the light emitting diodes LED1 and LED2 are switched on. The current necessary for light emission is supplied from battery B1.

The base of transistor T6 is connected to battery B1 through resistor R7 and to the light emitting diode through resistor R8.
Connected to LED1 and LED2. transistor
Resistors R5 and R6 are connected in front of the bases of T3 and T4, respectively.

Transistor, limited by buffer amplifier
Transistor conducts at the same time as T3 or T4 conducts
Via T6 and resistors R9 and R10, the oscillator transistor T5 is switched on, and the energy stored in the inductance of the circuit part A1 during the switching process is released via the transistor T5 towards ground.

The piezoelectric ceramic diaphragm 10 of the acoustic signal generator Bu (buzzer) is excited via the excitation electrodes 11 and 12 by the voltage pulses generated at this time. Due to the elastic return of the piezoceramic diaphragm, the base of the oscillator transistor T5 is blocked again via the acoustic return electrode 13.

Oscillator C is an active four-terminal circuit (transistor T5)
acts non-linearly on the electrodes 11 and 12 of the piezoceramic diaphragm 10, and due to the electro-acoustic feedback the oscillator C operates at the natural frequency of the piezoceramic diaphragm 10, with the inductance L acting as an energy storage device. play the role of

An acoustic signal generator of the type described here is the subject of German Patent Application No. 3013788.

If the input voltage applied to the contact tapes 4 and 5 is 6V or more and less than 12V, the voltage polarity indicating light emitting diodes LED1 and LED2 are switched on, and accordingly the battery circuit B and the acoustic signal generator Bu are switched on. Ru.

Diodes D10 and D11 are for reducing the voltage division ratio of the input voltage divider consisting of resistors R1 and R2 or R3 and R4 at low input voltages.

For high input voltages, transistors T1 and T2 as emitter followers and diodes serve to increase the blocking voltage of these transistors.
Current flows through D12 and D13 to a voltage divider consisting of resistors R13, R14 and R15.

The current proportional to this input voltage is the transistor
Transistor T10 is a constant current source at the base of T10
Consider the potential sufficient to cause conduction through T15.

To save current, a voltage pulse taken from the oscillator C via the supply capacitor C4 and limited in amplitude by the zener diode D4 is applied to the base of a constant current source T15, thereby providing a constant voltage pulse at the same frequency as the oscillator C. A pulsed current of amplitude is formed,
Transistor T10, respectively switched on,
T9 or T8 (e.g. transistor at 12V)
Light emitting diode LED3, LED4 via T10)
or LED5 (e.g. light emitting diode at 12V)
It is also possible to cause the LED3) to emit light intermittently.

For higher input voltages, divider resistor R15
The voltage drop at the transistor increases
T9 is switched on and transistors T9 and T10
The transistor T10 is switched off again due to the differential amplification effect between the light emitting diode
LED4 is switched on.

The switching on of the transistor T8, which, like the transistors T9 and 10, is a transistor for voltage indication is likewise effected via the resistor R14 at higher input voltages.

Zena diodes D1 and D2 in the full-wave rectifier circuit also serve as voltage limiting.

The zener diode D5 or D6 prevents the voltage drop from increasing with increasing input voltage after the base of the corresponding transistor T9 or T10 reaches the threshold voltage, respectively, and limits the operating range of the transistor to as many indications as possible. It serves to make it available for the display step (in the example shown, the display step by transistors T8, T9 and T10).

The 12V, 24V and 50V display steps are combined into one cascade E and are powered by battery B1.

The 110V, 220V, 380V and 660V display steps are combined in another cascade F.

Light emitting diode of each display step of cascade circuit F
When the input voltage is 110 or more, LED6 to LED9 are connected through a full-wave rectifier circuit consisting of diodes D8 and D9 and Zena diodes D1 and D2, and a threshold circuit consisting of Zena diode D3, similar to the cascade circuit E. In principle, they are switched on when the input voltage reaches the respective voltage range.

The voltage divider of cascade circuit F is voltage dividing resistors R16, R17,
Consists of R18 and R19.

The function of Zena diode D7 is Zena diode D5
and functions equivalent to D6.

Capacitors C3, C5 and C6 are smoothing capacitors required in case of AC voltage testing.

Resistor R20 is connected to the emitter of constant current source T16 and the base of transistor T14.

Resistor R21 is connected in front of the base of constant current source T16.

In the cascade circuit F, the current necessary for the light emitting diode to emit light is supplied from the booster circuit A1 with a voltage higher than the battery voltage, and is intermittent at the frequency of the oscillator C.

Thus, oscillator C also acts as a chopper oscillator to conserve the current drawn from the battery to make the light emitting diode emit light.

Furthermore, oscillator C feeds a voltage multiplier circuit consisting of diodes D16, D17, D19 and D20 and capacitors C7 and C8 via coupling capacitor C2 to
It plays the role of generating 50V voltage. The thus boosted voltage is applied to capacitor C1 within energy storage device A2. When switch S2 is switched from the rest position to the operating position, the capacitor
The charge stored in C1 is transferred to resistor R12 and diode
It is applied to the input side of buffer amplifier D via D14.

The resistor R12 shown within the dashed box in FIG. 4 may be replaced by the circuit shown in FIG. In this case, the charge stored in the capacitor C1 is applied via the coupling capacitor C9 to the input of the buffer amplifier D via the transistor T7 which is chopped at its frequency by the oscillator C. This extends the time it takes for capacitor C1 to complete discharging.

In either case, a current greater than the current flowing into the input side of the buffer amplifier due to the voltage applied across the contact tapes corresponding to the maximum display step will flow into the capacitor.
Due to the discharge of C1, it flows to the input side of the buffer amplifier.
Therefore, the functional soundness of all the display steps can be checked from when the discharge is started by switching the switch S2 until the discharge is completed. During this inspection, a sound is emitted by an acoustic signal generator.

Resistors R22 and R23 are connected after the cascade E or F.

Switch S1 is a Zena diode in the rest position
Bridged by D18. In this state the test device is in voltage test mode.

When the switch S1 is switched from the inactive terminal 16 to the active terminal 17, the battery B1 is switched on via the protection diode D15. If a conductor is present between contact tapes 4 and 5, that conductor is tested.

If the contact tapes 4 and 5 are brought into direct contact with each other, a self-inspection is carried out as described above. The energy storage device is also charged during this self-check.

To reduce the discharge time constant, switch S2 connects resistor R11 in parallel to capacitor C1.

In Fig. 4, partial circuit A is further divided into three parts surrounded by dashed lines, and it also shows which part of the other circuits the input/output terminals of partial circuit A are connected to. has been done.

Components used in circuits (inductance, resistance, capacitor, diode, Zena diode,
The choice of transistor (transistor, light emitting diode) depends on the desired voltage range. Its selection can be made without difficulty by a person skilled in the art based on the disclosure of the present invention.

Next, a circuit for temporarily lowering the input resistance will be explained with reference to FIG. Test grip 1 with contact tape 4 and display grip 2 with contact tape 5 are connected to each other by a shielded cable 6. The high resistance series resistor R30 in the test grip, the high resistance series resistor R0 in the display grip and the overall circuit 18 form a high resistance series circuit.

When the voltage under test is applied between the contact tapes and the pushbutton switch 27 is pressed, at least one PTC resistor 19 is connected in parallel to the series circuit described above. A constant resistor 23 is connected in series with this PTC resistor 19, thereby determining the time constant of the self-heating process.

In order to lower the load resistance even further if necessary, other PTC resistors 20, 21 and 22 are connected in parallel to the PTC resistor 19, and other constant resistors 24, 25 and 26 are connected in parallel to the constant resistor 23. Connected.

FIG. 7 shows the relationship between load current I and time t at various applied voltages.

Curve X is when the applied voltage is 380V, and PTC
It shows that the effective time of the resistance is about 4 seconds. That is, pushbutton switch 27 (FIG. 6)
When pressed, a 4.2 kΩ resistor is switched on for approximately 4 seconds and is therefore active, thereby
A current of 89mA flows. A resistance of 4.2 kΩ can be obtained, for example, by connecting three resistors in parallel.

Curve Y is for an applied voltage of 220 V and shows that the effective time is 18 seconds when the same 4.2 kΩ resistor is switched on.

Curve Z is for an applied voltage of 110 V and shows that the effective time is more than 20 seconds when the same 4.2 kΩ resistor is switched on.

Generally, when measuring the starting force U _O of a voltage source with a voltmeter, if the internal resistance of the voltage source is R _I and the internal resistance of the voltmeter is R _E , the voltmeter will indicate U _O instead of U _O.・_RE /( _RI + _RE ). If the internal resistance R _I of the voltage source is sufficiently smaller than the internal resistance R _E of the voltmeter, the voltage indicated by the voltmeter will be approximately equal to U _O and will not change significantly even if the value of R _E differs. do not have. That is, such a voltage source can be considered to be a substantially constant voltage source. On the other hand, if the internal resistance R _I of the voltage source is not sufficiently small compared to the internal resistance R _E of the voltmeter, the voltage indicated by the voltmeter will be less than U _O , for example, if R _I = R _E U _O /2, and it changes greatly depending on the value of R _E . Further, it can be considered that the voltage source to be measured generally has a low internal resistance. On the other hand, a voltage source (voltage source other than the object to be measured) that causes a voltmeter to respond due to electrostatic induction or electromagnetic induction can generally be considered to have a significantly high internal resistance. Therefore, depending on whether the difference between the voltage indicated when the internal resistance of the voltmeter is high and the voltage indicated when the internal resistance of the voltmeter is low is small or large, it can be determined whether the indicated voltage is due to the voltage source being measured. It is possible to determine whether the voltage source is present or due to some other voltage source. This is utilized in the test device according to the invention. That is, the voltage source is determined in the following process.

For example, when testing 220V AC distribution voltage,
All light emitting diodes up to 220V will emit light.
If the above-mentioned light emitting diode continues to emit light when the pushbutton switch 27 is pressed to temporarily lower the internal resistance of the test device, it is determined that the 220V voltage is actually due to the AC power distribution system. On the other hand, although 220V was initially displayed, when pushbutton switch 27 was pressed, for example,
If only light emitting diodes up to 24V emit light, it is determined that the voltage of 220V is caused by a voltage source with high internal resistance, that is, a voltage source other than the AC power distribution system.

Components in the preferred embodiment C1 Capacitor in energy storage device A2 (22μF/50V) C2 Coupling capacitor (3.3μF/50V) C3 Smoothing capacitor (1μF/35V) C4 Coupling capacitor (330pF/100V) C5 Smoothing capacitor (1μF/35V) ) C6 Smoothing capacitor (1.8nF) C7 Coupling capacitor (47nF) C8 Coupling capacitor (47nF) C9 Coupling capacitor (selective, see Figure 5)
(330pF) D1 Zena diode for full-wave rectifier circuit (51V) D2 Zena diode for full-wave rectifier circuit (51V) D3 Zena diode for threshold voltage formation (13V) D4 Zena diode for pulse height limitation (2.4V) D5 Voltage Zena diode for voltage drop limitation (5.1V) D6 Zena diode for voltage drop limitation (3.3V) D7 Zena diode for voltage drop limitation (6.8V) D8 Full-wave rectifier circuit diode (1N4148) D9 Full-wave rectifier circuit diode (1N4148) ) D10 Diode for reducing the voltage division ratio of R1/R2 (1N4148) D11 Diode for decreasing the voltage division ratio of R3/R4 (1N4148) D12 Diode for increasing the blocking voltage of T1 (1N4148) D13 Diode for increasing the blocking voltage of T2 Boosting diode (1N4148) D14 Diode after S2/15 (1N4148) D15 Protection diode before B1 (1N4148) D16 Diode used for boosting together with D17, D19, D20 (for example 1N4148) D17 D16, D19, D20 Diode (1N4148 for example) used for boosting together with D18 Zena diode (24V) in circuit part A3 D19 Zena diode (16V) used for boosting together with D16, D17, D20 D20 Diode (1N4148) used for boosting together with D16, D17, D19 ) L Inductance in circuit part A1 (100 mH) LED1 6V and light emitting diode for negative polarity (e.g. Siemens CQV 10-5/LD30) LED2 6V and light emitting diode for positive polarity (e.g. Siemens CQV 10-5/LD30) LED3 for 12V Light emitting diodes (e.g.
Siemens CQV 10-5/LD30) LED4 24V light emitting diode (e.g.
Siemens CQV 10-5/LD30) LED5 50V light emitting diode (e.g.
Siemens CQV 10-5/LD30) LED6 110V light emitting diode (e.g.
Siemens CQV 10-5/LD30) LED7 220V light emitting diode (e.g.
Siemens CQV 10-5/LD30) LED8 380V light emitting diode (e.g.
Siemens CQV 10-5/LD30) LED9 660V light emitting diode (e.g.
Biemens CQV 10-5/LD30) R0 High resistance series resistor (330kΩ) R1 Input voltage divider resistor (100kΩ) R2 Input voltage divider resistor (180kΩ) R3 Input voltage divider resistor (100kΩ) R4 Input voltage divider resistor (180kΩ) R5 Resistor before T3 (47kΩ) R6 Resistor before T4 (47kΩ) R7 Resistor before T6 (100kΩ) R8 Resistor before T8 (3.9kΩ) R9 Resistor before R10 of oscillator C (150kΩ) R10 Resistor before T5 of oscillator C (15kΩ) R11 Resistor (150kΩ) R12 Resistor (selective, see Figure 4) (5.6kΩ) R13 Display step 50V voltage division resistor (6.8kΩ) R14 Display step 24V voltage division Resistor (8.2kΩ) R15 Display step 12V voltage dividing resistor (100kΩ) R16 Display step 660V voltage dividing resistor (6.8kΩ) R17 Display step 380V voltage dividing resistor (2.4kΩ) R18 Display step 220V voltage dividing resistor (5.1 kΩ) R19 Display step 110V voltage division resistor (10kΩ) R20 Resistor between T14 and T16 (15kΩ) R21 Resistor before T16 (7.5kΩ) R22 Resistor (51Ω) R23 Resistor (68Ω) R30 High resistance series Resistor (330kΩ) R31 Resistor (selective, see Figure 5) (100kΩ) T1 Transistor of the emitter follower in the buffer amplifier (BC237) T2 Transistor of the emitter follower in the buffer amplifier (BC237) T3 Transistor for LED2 (BC237) T4 LED1 (BC237) T5 Oscillator transistor (BC546) T6 Switch-on transistor in battery circuit B (BC556) T7 Buffer transistor (selective, see Figure 5)
(BC556) T8 Display step 50V transistor (BC237) T9 Display step 24V transistor (BC237) T10 Display step 12V transistor (BC237) T11 Display step 660V transistor (BC546) T12 Display step 380V transistor (BC546) T13 Display Step 220V transistor (BC546) T14 Display step 110V transistor (BC546) T15 Constant current source for cascade E (BC237) T16 Constant current source for cascade F (BC237)

[Brief explanation of drawings]

Fig. 1 is a diagram showing the external appearance of the entire test equipment on an approximately 1:1 scale, Fig. 2 is a block circuit diagram for explaining the operating principle of the test equipment, and Fig. 3 is an overall view of a preferred embodiment of the test equipment. 4 is a circuit diagram showing a portion of the circuit of FIG. 3; FIG. 5 is a circuit diagram showing an alternative embodiment to the portion of the circuit of FIG. 4; FIG. 6 is a circuit diagram showing a portion of the circuit of FIG. FIG. 7 is a graph showing the relationship between load current and applied voltage when temporarily lowering the input resistance. 1...Test grip, 2...Display grip, 3
... Cable, 4, 5 ... Contact tape, 6 ...
Shield, 7, 8...Brim, 9...Dent, 10...
...Piezoelectric ceramic diaphragm, 11, 12...Excitation electrode, 13...Return electrode, 14...S2 rest side terminal, 15...S2 operating side terminal, 16...S1 rest side terminal, 17... Operating side terminal of S1, 18...
The entire circuit in the display grip, 19-22...
PTC resistance, 23-26... Constant resistance, 27...
Push button switch, A... partial circuit, B... battery circuit, C... oscillator, D... buffer amplifier, E, F
... Voltage display cascade circuit, G ... Battery case, A
1... Booster circuit, A2... Energy storage device,
A3...Continuity test and self-inspection circuit, B1...
...battery (12V), Bu...acoustic signal generator (buzzer), S1, S2...opening/closing elements.

Claims (1)

Claims: 1 connected by a cable 3 and comprising contact tapes 4, 5 and each including one high resistance series resistor (R30, R0) connected after the contact tapes 4, 5; Two grips 1 and 2
and one of these grips 2 has a voltage range (e.g. 6, 12, 24, 50, 110, 220, 380,
660V), an oscillator C that can drive the acoustic signal generator Bu, and an input current limited by both series resistors (R30, R0). Built-in battery B1
(a) A buffer amplifier D that is powered by an oscillator C, and a buffer amplifier D that enables step display of the voltage to be tested and its polarity as well as switch-on of an acoustic signal generator by switching on the display current from the battery. A booster circuit A1 is provided which serves to increase the oscillator voltage limited by the battery, and (b) is connected to the output side of the booster circuit A1 via a switching element S2, and this switching element S2 is An energy storage device A2 (e.g. in the form of a capacitor C1) is provided which is charged by the output voltage of the booster circuit A1 while in the rest position; The switching element S2 in the position can be switched into the operating position in order to transfer the charge present in the energy storage device A2 to the input side of the buffer amplifier D, thereby sequentially checking the health of all display functions of the test device. Yes, (d) Oscillator C connects the display element (LED6 or
The display current given to LED9) and the display current given to the display elements (LED3 to LED5) of the voltage under test within the lower voltage measurement range (6V or more, less than 110V) are switched on (that is, chopped) intermittently for short periods of time. (T15, T16)
(e) Another switching element S1 is provided which bridges the Zena diode D18 in the rest position, and when this switching element S1 is switched to the operating position, the switch of the battery B1 is switched on. Accordingly, if there is a conductor to be tested between both contact tapes 4 and 5, a continuity test is performed on it, and both contact tapes 4 and 5 are tested for continuity.
and 5 in direct contact with each other, the health of the battery B1, the acoustic signal generator Bu, the optical display element for polarity display (LED1 and LED2), and the optical display element for voltage display (LED3) corresponding to the battery voltage. A test device for displaying voltage and its polarity and for continuity testing, characterized in that the test device is inspected and a capacitor (C1) in an energy storage device is charged. 2 (a) Two high-resistance, high-withstand-voltage series resistors are connected in front of the buffer amplifier D, which serves as an input circuit, and one of them (R0)
is housed in one grip 2, and the other (R30) is housed in the other grip 1, separated by a cable 3 with a shield 6, and both series resistors (R0, R30) limits the current produced by the voltage under test and connects the input voltage divider (resistors R1 and R2 or R3 and R4)
and the following transistors (T1 and
The transistor (T1 or T2) is formed from the transistor (T1 and T2) and the Zener diode (D1 and D2) depending on the polarity of the voltage under test. The transistor (T3 or T4) for polarity display becomes conductive depending on the polarity, and the light display element (LED2) for positive polarity display or negative polarity display becomes conductive through the full-wave rectifier circuit. The current circuit of the light display element (LED1) for use, or the AC voltage for both light display elements (LED1 and
The current circuit for LED2) is formed, and at the same time the polarity display transistor (T3 or T4) is made conductive by the battery circuit switching transistor (T6).
By obtaining a potential difference between the base of the battery B1 and the positive potential of the battery B1, the battery circuit B is switched on, and the current necessary for light emission of the light display element for polarity display is supplied from the battery B1, and (b) the oscillator C is activated. Oscillation transistor (T5), resistor (R9 and R10), inductance L and 3
(c) The booster circuit A1 consists of four diodes (D16,
D17, D19, and D20), three coupling capacitors (C2, C7, and C8), and one inductance L, which is powered via an oscillator C and (d) energy Storage device A2 is a capacitor (C1)
and a diode (D17) that plays the role of peak value rectification.
and a switching element S2 that interconnects these capacitors (C1) and diodes (D17) in the rest position, and voltage pulses from the booster circuit A1 are applied to the capacitors (C1) by peak value rectification (diode D17). As a result, the capacitor (C1) is charged to the peak value of the voltage pulse, and (e) the connection path between the operating position side terminal of the switching element S2 of the energy storage device and one input terminal of the buffer amplifier D is charged. 2. The test device according to claim 1, further comprising a protection diode (D14) and a current limiting resistor (R12). 3. The voltage display circuit for step displaying the individual voltage ranges is divided into two voltage display cascade circuits E and F that are supplied with display currents separate from each other. ) is fed from the battery B1 via the switching transistor (T6), the cascade F for the upper voltage range (above 110 V) is fed from the booster circuit A1, and both cascades E and F are supplied with current saving power. 3. The test device according to claim 1, wherein the test device is intermittently opened and closed (that is, chopped) at the frequency of the oscillator C. 4 A circuit in which the current limiting resistor (R12) between the operating position side terminal of the switching element S2 of the energy storage device and the protection diode (D14) is composed of a resistor (R31), a buffer transistor (T7), and a coupling capacitor (C9). The collector of the buffer transistor (T7) is replaced by a protection diode (D14).
, its emitter and one terminal of the resistor 31 are connected to the operating position side terminal 15 of the switching element S2, and the base of the buffer transistor (T7) is connected to the other terminal of the resistor 31 and one pole of the coupling capacitor (C9), 4. The test device according to claim 2, wherein the other pole of the coupling capacitor (C9) is further connected to an acoustic signal generator Bu. 5. For the purpose of temporarily lowering the high (600 kΩ or more) input resistance, the entire circuit 18 in grip 2 and the high resistance series resistors (R0 and R30) housed in grips 2 and 1, 200Ω and 5kΩ
and guarantee a self-heating time constant (stopping time t _aB ) of at least 1 second.
5. The test device according to claim 1, wherein the PTC resistors 19, 20, 21, and 22 are connected in parallel so that they can be selectively switched on. 6. Each PTC resistor 19, 20, 21, 22 and a resistor 23, 24, 2 having a practically constant resistance value.
5. The test device according to claim 5, wherein the test devices 5 and 26 are connected in series. 7. A patent claim characterized in that the selectively switchable PTC resistors 19, 20, 21, 22 have a rated resistance value in the range from 200 kΩ to 5 kΩ when the input resistance (R0 + R30) of the test device is 660 kΩ. The test device according to the scope of item 5 or 6. 8 At least one constant resistance 23, 24, 2
8. Test device according to claim 7, characterized in that 5, 26 have a resistance value between 1 kΩ and 15 kΩ.