JP5028658B2 - Probing adapter and probe apparatus using the same - Google Patents

Description

  The present invention relates to an adapter and a probe device used when measuring a power line serving as a transmission path when installing a power line communication apparatus used for, for example, power line communication (PLC).

In recent years, communication devices that use a power line as a transmission line and superimpose a communication signal frequency on a power frequency that is commercial power for transmission are becoming widespread, and cases of measuring the state of the power line as a transmission line are increasing. .
In the transmission of high-frequency signals using a power line, the transmission side and the reception side are not directly connected by a single communication cable on a one-to-one basis, but in the middle of the transmission path, branches, transformers, distribution boards, Generally, various devices such as wattmeters and home appliances are scattered.
For this reason, it is known that impedance frequently changes in the course of the transmission path, resulting in reflection and attenuation of high-frequency signals. Therefore, since transmission characteristics (line quality) are different for each transmission path, when installing a power line carrier device, transmission path characteristics are examined in advance and various measures are taken as necessary.

Usually, a measuring instrument called a network analyzer or a spectrum analyzer is used to measure transmission path characteristics.
FIG. 5 shows an example in which the transmission characteristics of the power line are acquired using a network analyzer.
In FIG. 5, the frequency sweep signal output from the network analyzer is injected into the power line via the injector and the injection coupling unit, and the frequency sweep signal propagated through the power line is extracted to the coupling unit and the extractor. The transmission characteristics of the power line are obtained by forming a closed circuit back to the network analyzer via
As an example of using a spectrum analyzer, a predetermined measurement signal is transmitted from the power line carrier communication device connected to the power line, and the measurement signal transmitted through the power line is measured by the spectrum analyzer. It will be.

As described above, when measurement is performed using the above-described measuring instrument with the electric wire as the object to be measured, it is often impossible to directly measure the measuring instrument directly to the electric wire.
This is because, as a matter of course, commercial power (for example, AC 100 V or 200 V) is always applied to the power line, and it is necessary to provide an interface in consideration of this on the measuring instrument side. That is, in power line communication, communication is performed using a band (for example, 2 to 30 MHz band) different from the above-described commercial power 50 Hz (or 60 Hz). Communication signal level is extremely low. For this reason, measurement is performed in a measurement range suitable for measuring communication signals while eliminating components of commercial power and limiting to a desired band related to communication signal frequencies. The connection must meet the interface conditions.

  When measurement is performed using a power line as an object to be measured, for example, connection is made via an adapter (a desired signal band extracting unit, a filter unit, a balanced / unbalanced converting unit) as shown in FIG. In the example shown in this figure, a signal derived from the power line 1 through the probe 3 is guided to the signal band extraction unit 10 through the coupling capacitor C in the adapter 4, and the signal band extraction unit 10 The signal from which the component has been removed is further passed through only a desired frequency band by the filter unit 20 and then matched with the input condition (for example, 50Ω unbalance) of the measuring instrument 2 via the balanced / unbalanced converting unit 30. It is an adapter that supplies a signal to the measuring instrument in a live state.

Japanese Patent Application Laid-Open No. 2005-070022 is a patent document in which an adapter is provided between such an object to be measured and the measuring instrument and is connected to the measuring instrument. The adapter (line balance measurement probe) shown in this patent document is used when measuring the balance of a line to be measured such as a power line, and includes a plurality of choke transformers and filters. According to this, a large dynamic range can be secured over a wide frequency band in the line balance measurement.
However, as described above, when the adapter is provided in the previous stage of the measuring instrument and connected to the measuring instrument, and the electric wire is measured as the object to be measured, the measuring instrument may be broken.
Prediction of the cause is that a surge has occurred in the power line and an excessive voltage is input to the measuring instrument, or an excessive potential difference exists between the GND (ground potential) of the measuring instrument and the potential of the object to be measured. This may have occurred, or when the probe portion is configured by winding a long cable, charges were accumulated in the cable portion.
Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 2005-164419, it is conceivable to provide a protective function such as a residual current circuit breaker before the input to the measuring instrument (impedance tester).
Japanese Patent Laying-Open No. 2005-070022 JP 2005-164419 A

However, when the residual current circuit breaker is incorporated in the probing adapter, there is a problem in that the size of the circuit breaker increases.
The problem to be solved by the present invention is a small-sized probing adapter that can be applied to a scene of measuring a power line as an object to be measured, and efficiently prevents damage to a measuring instrument due to an excessive voltage or the like. An object of the present invention is to provide a probing adapter configured as described above and a probe device using the same.

In order to solve the above problems, the invention according to the probing adapter of the present invention includes a probe connection terminal to which a probe for taking out a signal to be measured from an object to be measured is connected, a measuring instrument connection terminal connected to a measuring instrument, Is a probing adapter for adding a power line to an object to be measured, a signal extraction circuit that blocks frequencies below the power supply frequency band and passes signals in a higher frequency band, and a desired frequency A filter circuit that passes only a band; a balanced / unbalanced conversion circuit that uses the output of the filter circuit as a balanced input; a fuse that is connected in series between the probe connection terminal and the signal extraction circuit; and the signal extraction two-way Zener diode formed by joining anodes connected in parallel between the circuit and the filter circuit, complaining of the balanced / unbalanced conversion circuit Characterized in that and a PCT thermistor connected in series between the output and the measuring instrument connection terminal.

Further, the invention according to the probe device of the present invention is characterized in that in the probe device comprising the probing adapter of the present invention and a probe, the probe is provided with an outlet plug at a tip portion coupled to the object to be measured. To do.
Further, the invention according to the probe device of the present invention is characterized in that in the probe device comprising the probing adapter of the present invention and a probe, the probe comprises a ferrite core at a tip portion coupled to the object to be measured. To do.

  The probing adapter according to the present invention and the probe device using the same are obtained by arranging the first protection element, the second protection element, and the third protection element having different characteristics at appropriate positions in the adapter. By adopting a small protection element while efficiently preventing damage to the measuring instrument due to excessive voltage or the like, a small probing adapter and a probe device using the same can be realized. This is particularly convenient when measuring transmission line characteristics (for example, 2 to 30 MHz band in a power line) in a PLC.

Embodiments according to the present invention will be described below with reference to the drawings.
FIG. 1 is a functional block diagram showing a configuration of a probing adapter according to the present invention. Note that functional blocks that are the same as the configuration shown in FIG. 6 as a conventional example are assigned the same reference numerals, and descriptions thereof are omitted.
The probing adapter 4 shown in this figure includes an input connector terminal 5 and an output connector terminal 6 on the exterior of the main body case. Further, a first protective element connected to the input connector terminal 5 is provided inside the main body case. 7, a signal band extraction unit 10 connected to the first protection element 4, a second protection element 8 connected to the signal band extraction unit 10, a filter unit 20 connected to the second protection element 8, and a filter The balance / unbalance conversion unit 30 connected to the unit 20 and the third protection element 9 connected to the balance / unbalance conversion unit 30 are provided. The third protection element 9 is connected to the output connector terminal 6.
The input connector terminal 5 can be connected and fixed to a probe 3 for deriving a signal to be measured by bringing an electrode into contact with a measurement location. For example, a measurement signal is input to the input connector terminal 5 via the probe 3 when the lamp line 1 is the object to be measured. On the other hand, the output connector terminal 6 can be connected and fixed to the measuring instrument 2 such as a spectrum analyzer, and the measurement signal processed by the adapter 4 is output to the measuring instrument 2.

FIG. 2 is a diagram illustrating a specific circuit configuration example of the main components illustrated in FIG. 1.
In the example of this figure, the probe 3 whose tip electrode part is an outlet plug is connected to the input connector terminal 5 of the probing adapter 4, and the output connector terminal 6 serves as a measuring instrument 2 as a handy tester. This shows a scene connected to a type of spectrum analyzer.
Hereinafter, the internal configuration of the adapter 4 will be described.
The first protection element 4 is a fuse F, and is inserted in series in either one of the two wires between the input connector terminal 5 and the signal band extraction unit 10. Although the illustrated example is one of the two lines, it may be inserted in series in both lines.
The signal band extraction unit 10 includes a coupling capacitor C and a transformer T1, and the coupling capacitor C is inserted in series in each of the two wires, and the ends thereof are connected to both ends of the primary winding of the transformer T1 and terminated. Circuit configuration.
The second protection element 8 is a bidirectional Zener diode ZD having anodes joined together, and is inserted in parallel between two wires extending from both ends of the secondary winding of the transformer T1 of the signal band extraction unit 10.
The filter unit 20 is a band-pass filter including a high pass filter (HPF) and a low pass filter (LPF). Here, since it becomes complicated, a specific circuit is not shown, but various general filter circuits can be applied. In this example, both HPF and LPF are composed only of passive elements.
The balanced / unbalanced conversion unit 30 includes a transformer T2, and terminates by connecting two wires extending from the filter unit 20 to both ends of the primary winding of the transformer T2.
The third protection element 9 is a polymer-based PTC (Positive Temperature Coefficient) thermistor Th. One of the terminals of the secondary side winding of the transformer T2 of the balanced / unbalanced converter 30 and the output connector terminal 6 is one of the third protective elements 9. Inserted in series with the wire.

The probe device (the probe 3 and the probing adapter 4 combined) shown in this figure functions as follows, that is, the measurement signal introduced into the probing adapter 4 via the probe 3 is PLC transmitted to commercial power The signal is superimposed. When this signal is given to the closed circuit of the fuse F, the coupling capacitor C, and the transformer T1 (primary side), a high-frequency AC component including a PLC transmission signal appears at both ends of the secondary side of the transformer T1. Here, the fuse F is blown and closed when a current exceeding the predetermined rated current of the fuse flows due to an excessive input coming from the lamp line as the object to be measured or a short mode failure in the probing adapter 4. And the signal function to the subsequent stage in the probing adapter 4 is cut off. Most of the commercial power is removed from the signal generated on the secondary side of the transformer T1, and the signal voltage level (low frequency band near 50 Hz) related to the commercial power is remarkably small.
The Zener diode ZD functions to prevent transmission of a high voltage to the subsequent stage by flowing a current across the secondary side of the transformer T1 when a voltage exceeding a predetermined rated voltage of the Zener diode is applied. In order to reduce noise generated from the Zener diode, it is preferable to use a multistage connection type Zener diode with a low voltage rating. Further, a varistor having equivalent functional characteristics may be used in place of the Zener diode ZD.

In the filter unit 20, first, the high-pass filter (HPF) blocks a band of less than about 1 MHz, passes the frequency component exceeding the band, and the low-pass filter (LPF) uses a high frequency exceeding about 30 M. It functions to obtain only a desired PLC transmission signal band by blocking the passage of the components and allowing the frequency components below the components to pass. Note that a filter circuit called an anti-aliasing filter is preferably applied as the low-pass filter used here.
Then, the measurement signal (desired PLC transmission signal band) output from the filter unit 20 is transmitted through a transformer T2 with a relative reference potential separated between the primary side winding and the secondary side winding. Is done. That is, the transformer T2 is provided to perform balanced / unbalanced conversion, and the secondary side of the transformer T2 is set to the reference potential of the measuring instrument 2 to which the output connector 6 is connected. For example, when the input terminal interface of the measuring instrument 2 is a general 50Ω imbalance, the transformer T2 is set to provide an interface that matches this.
The PCT thermistor Th functions to increase the internal resistance value in proportion to the temperature rise caused by the flowing current. That is, the resistance value increases between the probing adapter 4 that outputs the measurement signal and the measuring device 2 that receives the measurement signal due to an overcurrent or the like, so that the resistance value increases and the circuit current is limited to be reduced. The function of current protection is exhibited and the influence on the measuring instrument 2 is reduced. Since the PCT thermistor Th is a self-recovering type in which the resistance value decreases as the temperature decreases, replacement after operation like a fuse is unnecessary.

  According to the probe apparatus configured as in the above-described embodiment, the first protection element, the second protection element, and the like, which prevent excessive transmission of current or voltage at the appropriate place in the probing adapter 4; Since the third protection element is provided, in the case where measurement is performed using a power line to which commercial power is applied as an object to be measured, only a desired PLC transmission signal band is used as a measurement signal to the measuring instrument. A small probe device that can prevent the influence on the measuring instrument due to an excessive input from the lamp line or a relative reference potential difference with the measuring instrument can be realized.

Next, another embodiment of the probing adapter and probe device according to the present invention will be described.
FIG. 3 is a diagram showing a circuit configuration example in which a power supply unit and an amplification unit are added to the components shown in FIG. Note that the same functional blocks as those in the configuration shown in FIG.
In this example, when the filter circuit 20 is configured using an active element such as a transistor, it is possible to obtain a higher level of filter characteristics than when only the passive element is configured, but it is necessary to supply operating power.
Therefore, a power supply unit 40 including an AC / DC converter and a built-in battery is provided in the probing adapter 4, and a constant voltage direct current is supplied as operating power Vcc by the power supply unit 40. The AC / DC converter of the power supply unit 40 uses the commercial power of the lamp line 1 by branching and inputting the two lines input to the signal band extraction unit 10. The built-in battery is a secondary battery having a charging function, and can be charged when a direct current is supplied from the AC / DC converter.
Furthermore, an amplifier (AMP) having a signal amplification characteristic that compensates for the attenuation characteristic of the probing adapter 4 when supplying the measurement signal from the object to be measured (lamp line 1) to the measuring instrument 2 through the probing adapter 4 50 is provided after the filter circuit 20.
In the probe apparatus configured as described above, when the measurement object is a power line, the operating power Vcc in the probing adapter 4 is obtained by connecting the probe 3 whose tip is an outlet plug to the outlet. As a result, power can be supplied to the filter circuit 20 and the amplifier 50 having active elements, and a measurement signal with excellent filter characteristics and attenuation loss compensation can be supplied to the measuring instrument 2.

Moreover, the form example of the probe part used for the probing apparatus which concerns on this invention is illustrated.
FIG. 4 is a diagram showing a modification of the probe 3 used by being connected to the probing adapter 4. The probe shown in this figure includes a connector portion 101 and a cord portion 102, and (a) to (e) show different forms of tip portions that contact the object to be measured.
The probe 3 shown in (a) has a configuration in which the tip is an outlet plug 103. The probe 3 shown in (b) is a form in which the tip part is a ferrite core 104 and an induction winding 105. The ferrite core 104 may be a split type clipping type. The probe 3 shown in (c) is a form in which the tip is a clip 106. The probe 3 shown in (d) is a form in which the tip is a screw terminal 107. The probe 3 shown in (e) has a configuration in which the tip is a straight probe 108.
In particular, the probe forms shown in the above-described (a) and (b) are forms that exhibit special convenience during measurement work when the object to be measured is a power line.

  As described above, when the probe device according to the present invention (a combination of the probing adapter 4 and the probe 3) is used, the first to third protection elements are arranged at appropriate positions on the probing adapter 4. When measuring the transmission line characteristics of a wire, it is possible to provide a small, light and easy-to-operate probe device that can efficiently suppress the influence of the power line 1 on the measuring device 2.

It is a functional block diagram which shows the structural example of the probe apparatus which concerns on this invention. It is a circuit diagram (Example 1) which shows the internal structural example of the adapter for probing which concerns on this invention. It is a circuit diagram (Example 2) which shows the internal structural example of the adapter for probing which concerns on this invention. It is a figure which shows the structural example of the probe used for the probe apparatus which concerns on this invention. It is explanatory drawing which showed the example of embodiment regarding the conventional power line measurement. It is a functional block diagram which shows the structural example of the conventional probe apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric light line, 2 ... Measuring device, 3 ... Probe, 4 ... Adapter for probing, 5 ... Input connector terminal, 6 ... Output connector terminal, 7 ... 1st protection element, 8 ... 2nd protection element, 9 ... 3rd protection element, 10 ... Signal band extraction part, 20 ... Filter part, 30 ... Balance / Unbalance Conversion unit 40 ... Power supply unit 50 ... Amplification unit 101 ... Connector unit 102 ... Code unit

Claims (6)

A main body case, a probe connection terminal for connecting a probe for extracting a signal to be measured from the object to be measured, and a measuring instrument connection terminal for connecting a measuring instrument;
In the main body case,
A signal extraction means for blocking a signal below the power supply frequency flowing through the power line, and allowing a higher frequency signal to pass through;
Filter means for passing only a desired frequency band;
Balanced / unbalanced converting means using the output of the filter means as a balanced input;
A fuse connected in series between the probe connection terminal and the signal extraction means;
A bidirectional Zener diode in which anodes connected in parallel between the signal extraction means and the filter means are joined ;
A PCT thermistor connected in series between the unbalanced output of the balanced / unbalanced conversion means and the measuring instrument connection terminal;
A probing adapter for measuring a power line characterized by comprising The filter means is a band-pass filter that passes a signal having a frequency corresponding to a carrier signal of the power line carrier device, and the band-pass filter is realized by a combination of a high-pass filter and a low-pass filter. The probing adapter according to claim 1, wherein an anti-aliasing filter is used . 3. The power supply for the active filter according to claim 1, wherein the filter means is an active filter configured by an active element, and power supply means including an AC / DC converter and a battery is provided as a power supply for the active filter . Adapter for probing. The probing adapter according to any one of claims 1 to 3, wherein the Zener diode is a low-voltage rated multistage connection type Zener diode . A probe device comprising the probing adapter according to any one of claims 1 to 4 and a probe,
A probe device for measuring a power line, characterized in that the probe includes a power plug plug at a tip portion coupled to a measurement object . A probe device comprising the probing adapter according to any one of claims 1 to 4 and a probe,
  The probe device includes a ferrite core for extracting a signal from the power line, and a probe device for measuring the power line.