JP7768810B2 - Measurement method and measurement system - Google Patents

Description

This disclosure relates to a measurement method and a measurement system.

Patent Document 1 discloses a discharge device equipped with a discharger that passes current through a second conductor when the absolute value of the voltage of the conductor, with the ground potential as the reference potential, exceeds a predetermined voltage. In this discharge device, the anodes of multiple first diodes are connected to each of multiple conductors. The cathodes of multiple second diodes are further connected to each of the multiple conductors. The second conductor is connected to the ground. The first electrode of the discharger is connected to the cathodes of the multiple first diodes. The second electrode of the discharger is connected to the anodes of the multiple second diodes.

When the voltage on the conductor is positive and the absolute value of the voltage on the conductor exceeds a predetermined voltage, the discharger passes current through the first diode, the second conductor, and ground in that order. When the voltage on the conductor is negative and the absolute value of the voltage on the conductor exceeds a predetermined voltage, the discharger passes current through ground, the second conductor, and the second diode in that order. This keeps the absolute value of the voltage on the conductor below the predetermined voltage.

Japanese Patent Application Laid-Open No. 2022-14713

In Patent Document 1, communication takes place via two conductors included in a plurality of conductors. Patent Document 1 does not consider a method for measuring the characteristics of the discharge device related to this communication. It is preferable to measure the characteristics of a discharge device in a state close to its actual use state.

This disclosure was made in light of these circumstances, and its purpose is to provide a measurement method and measurement system that can measure the characteristics of a discharge device in a state close to its actual use.

A measurement method according to one aspect of the present disclosure measures the characteristics of a discharge device including a plurality of first diodes, each having an anode connected to a plurality of conductors; a plurality of second diodes, each having a cathode connected to the plurality of conductors; and a discharger, the first electrode of which is connected to the cathodes of the plurality of first diodes and the second electrode of which is connected to the anodes of the plurality of second diodes, that causes a current to flow through a second conductor different from the plurality of conductors when the absolute value of the voltage of the conductors reaches or exceeds a predetermined voltage. The measurement method includes the steps of applying a voltage between the first electrode and the second electrode and measuring communication characteristics related to communication via two conductors included in the plurality of conductors.

A measurement system according to one aspect of the present disclosure includes a discharge device having a plurality of first diodes, each having an anode connected to a plurality of conductors; a plurality of second diodes, each having a cathode connected to the plurality of conductors; a discharger having a first electrode connected to the cathodes of the plurality of first diodes and a second electrode connected to the anodes of the plurality of second diodes, and configured to pass current through a second conductor different from the plurality of conductors when the absolute value of the voltage of the conductors reaches or exceeds a predetermined voltage; a voltage application unit that applies a voltage between the first electrode and the second electrode; and a measurement unit that measures communication characteristics related to communication through two conductors included in the plurality of conductors.

According to the above aspect, the communication characteristics of the discharge device are measured.

1 is a block diagram showing a configuration of a main part of a communication system according to a first embodiment; FIG. 10 is a diagram illustrating the relationship between a reverse bias voltage and the magnitude of a junction capacitance. FIG. 10 is an explanatory diagram of a method for measuring communication characteristics. FIG. 2 is an explanatory diagram of the contents of communication characteristics. FIG. 10 is a circuit diagram of a discharge device in use according to a second embodiment. FIG. 2 is a circuit diagram of a power supply circuit. FIG. 2 is a circuit diagram of a power receiving circuit. FIG. 10 is a circuit diagram of the discharge device in a measurement state. FIG. 11 is a circuit diagram of a discharge device in a measurement state in embodiment 3.

Hereinafter, the present disclosure will be described in detail with reference to the drawings showing embodiments thereof.
(Embodiment 1)
FIG. 1 is a block diagram showing the main configuration of a communication system 1 according to a first embodiment. The communication system 1 includes a first communication device A1, a second communication device A2, and a discharge device 12. The first communication device A1 includes a first communication circuit 10 and a power supply circuit 11. The second communication device A2 includes a power receiving circuit 13 and a second communication circuit 14. The second communication device A2 is an electrical device that communicates, such as a security camera. Two communication lines 2 and 3 are connected between the first communication circuit 10 and the second communication circuit 14. The communication line 2 includes two communication conductors 2a and 2b. The communication line 3 includes two communication conductors 3a and 3b. Each of the communication lines 2 and 3 is, for example, a twisted pair wire. In this case, the two communication conductors 2a and 2b are twisted together. The two communication conductors 3a and 3b are also twisted together.

The first communication circuit 10 transmits a differential signal to the second communication circuit 14 via communication line 2. The second communication circuit 14 transmits a differential signal to the first communication circuit 10 via communication line 3. The differential signal propagating via communication line 2 is generated by adjusting the voltage difference between communication conductors 2a and 2b to various signal levels. Similarly, the differential signal propagating via communication line 3 is generated by adjusting the voltage difference between communication conductors 3a and 3b to various signal levels.

The power supply circuit 11, discharge device 12, and power receiving circuit 13 are arranged midway along the communication lines 2 and 3. The power supply circuit 11, discharge device 12, and power receiving circuit 13 are arranged in this order from the first communication circuit 10 side (left side) to the second communication circuit 14 side (right side). Each of the communication lines 2 and 3 passes through the inside of the discharge device 12.

The power supply circuit 11 of the first communication device A1 has a DC power supply 41 and two communication transformers 42, 43. The communication transformer 42 has two windings 42a, 42b. Each of the two windings 42a, 42b is wound around, for example, an annular iron core. The iron core is made of a magnetic material. One end of each of the two windings 42a, 42b is connected to the communication conductor 2a. The other end of each of the two windings 42a, 42b is connected to the communication conductor 2b. Therefore, the communication transformer 42 is located midway along the communication line 2.

Similarly, the communication transformer 43 has two windings 43a and 43b. The two windings 43a and 43b are wound around, for example, a ring-shaped iron core. One end of each of the two windings 43a and 43b is connected to the communication conductor 3a. The other end of each of the two windings 43a and 43b is connected to the communication conductor 3b. Therefore, the communication transformer 43 is located midway along the communication line 3.

The positive terminal of DC power supply 41 is connected midway through winding 42b. The negative terminal of DC power supply 41 is connected midway through winding 43b. Windings 42a and 43a are connected to the first communication circuit 10 via communication lines 2 and 3, respectively.

The power receiving circuit 13 of the second communication device A2 has a DC-DC converter 51 and two communication transformers 52, 53. The communication transformer 52 has two windings 52a, 52b. Each of the two windings 52a, 52b is wound around, for example, a ring-shaped iron core. One end of each of the two windings 52a, 52b is connected to the communication conductor 2a. The other end of each of the two windings 52a, 52b is connected to the communication conductor 2b. Therefore, the communication transformer 52 is located midway along the communication line 2.

Similarly, the communication transformer 53 has two windings 53a and 53b. The two windings 53a and 53b are wound around, for example, a ring-shaped iron core. One end of each of the two windings 53a and 53b is connected to the communication conductor 3a. The other end of each of the two windings 53a and 53b is connected to the communication conductor 3b. Therefore, the communication transformer 53 is located midway along the communication line 3.

The DC-DC converter 51 has a first input terminal, a second input terminal, and a first output terminal and a second output terminal. The first input terminal and the second input terminal of the DC-DC converter 51 are connected midway through the windings 52a and 53a, respectively. The first output terminal and the second output terminal of the DC-DC converter 51 are each connected to the second communication circuit 14. The windings 52b and 53b are connected to the second communication circuit 14 via the communication lines 2 and 3, respectively.

The DC power supply 41 of the power supply circuit 11 sends power to the power receiving circuit 13 via the communication lines 2 and 3. The power receiving circuit 13 receives the power sent by the DC power supply 41 of the power supply circuit 11 and supplies the received power to the second communication circuit 14. Current flows from the positive pole of the DC power supply 41 via the two communication conductors 2a and 2b to the first input terminal of the DCDC converter 51. In each of the communication conductors 2a and 2b, current flows from the power supply circuit 11 toward the power receiving circuit 13. From the second input terminal of the DCDC converter 51, current flows via the two communication conductors 3a and 3b to the negative pole of the DC power supply 41. In each of the communication conductors 3a and 3b, current flows from the power receiving circuit 13 toward the power supply circuit 11.

As a result, the output voltage of the DC power supply 41 is input to the first input terminal and second input terminal of the DCDC converter 51. The DCDC converter 51 transforms the input output voltage of the DC power supply 41 to a constant target voltage and applies the target voltage to the second communication circuit 14 from the first output terminal and second output terminal. As a result, power is supplied from the DC power supply 41 to the second communication circuit 14. The DC power supply 41 generates an output voltage using, for example, an AC voltage output from a commercial power supply. Specifically, the DC power supply 41 rectifies the AC voltage output from the commercial power supply to a DC voltage and smooths the rectified DC voltage. The DC power supply 41 outputs the smoothed DC voltage as an output voltage.

The power supply provided by the power supply circuit 11 is, for example, PoE power supply. PoE is an abbreviation for Power over Ethernet. Ethernet is a registered trademark. PoE power supply is power supply via a LAN cable. LAN is an abbreviation for Local Area Network.

As described above, the first communication circuit 10 transmits a differential signal via the communication line 2. When a differential signal is input to the winding 42a of the communication transformer 42, the winding 42b outputs the differential signal to the winding 52a of the communication transformer 52 via the communication line 2. When a differential signal is input to the winding 52a, the winding 52b outputs the differential signal to the second communication circuit 14 via the communication line 2. As a result, the second communication circuit 14 receives the differential signal. The communication transformers 42 and 52 are each insulated.

As mentioned above, the second communication circuit 14 transmits a differential signal via the communication line 3. When a differential signal is input to the winding 53b of the communication transformer 53, the winding 53a outputs the differential signal to the winding 43b of the communication transformer 43 via the communication line 3. When a differential signal is input to the winding 43b, the winding 43a outputs the differential signal to the first communication circuit 10 via the communication line 3. As a result, the first communication circuit 10 receives the differential signal. Each of the communication transformers 43, 53 is insulated. Each of the communication transformers 42, 43, 52, 53 is a so-called pulse transformer.

The discharge device 12 has four first diodes Da, four second diodes Db, a discharger F, and two terminals T1 and T2. The discharger F has a first electrode and a second electrode. A discharge conductor B is connected to the discharger F. The discharge conductor B is different from the communication conductors 2a, 2b, 3a, and 3b, and functions as a second conductor.

The anodes of the four first diodes Da are connected to the four communication conductors 2a, 2b, 3a, and 3b. The cathodes of the four second diodes Db are connected to the four communication conductors 2a, 2b, 3a, and 3b. The cathodes of the four first diodes Da are connected to the first electrode of the discharger F. The anodes of the four second diodes Db are connected to the second electrode of the discharger F. Terminals T1 and T2 are connected to the first and second electrodes of the discharger F, respectively. The discharge conductor B is grounded. Grounding is achieved, for example, by connection to earth.

In discharger F, when the voltage between the first electrode and discharge conductor B exceeds a certain threshold voltage, an arc occurs between the first electrode and discharge conductor B. As a result, current flows through the first electrode and discharge conductor B, and the absolute value of the voltage of the first electrode, with ground potential as the reference potential, is maintained below the threshold voltage. When the voltage between the second electrode and discharge conductor B exceeds the threshold voltage, an arc occurs between the second electrode and discharge conductor B. As a result, current flows through the second electrode and discharge conductor B, and the absolute value of the voltage of the second electrode, with ground potential as the reference potential, is maintained below the threshold voltage.

In the following, one of the conductors included in the communication conductors 2a, 2b, 3a, and 3b will be referred to as the target conductor. The target conductor may be any of the communication conductors 2a, 2b, 3a, and 3b. When the voltage of the target conductor is positive relative to the ground potential as the reference potential, and the voltage of the target conductor exceeds a predetermined voltage, the voltage between the first electrode and discharge conductor B exceeds a certain threshold voltage. As a result, in the discharger F, an arc is generated between the first electrode and discharge conductor B. Current flows in the following order: target conductor, first diode Da, discharger F, discharge conductor B, and ground.

When the voltage of the target conductor is negative relative to the ground potential, and the absolute value of the voltage of the target conductor exceeds a predetermined voltage, the voltage between the second electrode and discharge conductor B exceeds a certain threshold voltage. As a result, an arc occurs between the second electrode and discharge conductor B in discharger F. Current flows in this order: ground, discharge conductor B, discharger F, second diode Db, and the target conductor.

As described above, discharger F passes current through discharge conductor B when the absolute value of the voltage of the target conductor exceeds a predetermined voltage. This maintains the absolute value of the voltage of the four communication conductors 2a, 2b, 3a, and 3b, which have ground potential as their reference potential, below the predetermined voltage. For example, the two communication lines 2 and 3 between the power supply circuit 11 and discharge device 12 are located outdoors. In this case, when lightning strikes, the absolute value of the voltage of the target conductor, which has ground potential as its reference potential, may rise. Discharge device 12 maintains the absolute value of the voltage of the target conductor, which has ground potential as its reference potential, below the predetermined voltage, thereby protecting the power receiving circuit 13 from the application of overvoltage whose absolute value exceeds the predetermined voltage. Discharge device 12 is, for example, an SPD (Surge Protective Device).

Figure 1 shows the discharge device 12 in use. With respect to the output voltage of the DC power supply 41, the potential of the communication conductors 2a and 2b is higher than the potential of the communication conductors 3a and 3b. Therefore, a reverse bias voltage is applied to the two second diodes Db connected to each of the communication conductors 2a and 2b, and the two first diodes Da connected to each of the communication conductors 3a and 3b. No reverse bias voltage is applied to the remaining first diodes Da and second diodes Db.

In Figure 1, diodes to which a reverse bias voltage is applied are shown as black diodes. Diodes to which no reverse bias voltage is applied are shown as white diodes. Note that in Figures 3, 5, 8, and 9 described below, diodes to which a reverse bias voltage is applied are shown as black diodes, and diodes to which no reverse bias voltage is applied are shown as white diodes. Diodes have junction capacitance and also function as capacitors. The magnitude of the junction capacitance varies depending on the reverse bias voltage.

Figure 2 is an explanatory diagram of the relationship between reverse bias voltage and the magnitude of junction capacitance. When a positive voltage is applied to the cathode of a diode, with the anode potential as the reference potential, a reverse bias voltage is applied to the diode. In a diode, an N-type semiconductor and a P-type semiconductor are connected. When a reverse bias voltage is applied to the diode, electrons and holes move to the cathode and anode sides, respectively. As a result, a depletion layer, where no electrons or holes exist, is formed in the center of the diode. The depletion layer functions as an insulating layer, and junction capacitance is formed.

The greater the reverse bias voltage, the greater the width of the depletion layer. The width of the depletion layer is the horizontal length in Figure 2. The greater the width of the depletion layer, the smaller the junction capacitance. As a result, as shown in the upper part of Figure 2, the greater the reverse bias voltage, the smaller the junction capacitance. Frequency is represented by f. The magnitude of the junction capacitance is represented by C. The absolute value of the impedance of the junction capacitance is expressed as 1/(2 π f C). "・" represents the product. Therefore, the absolute value of the impedance is smaller as the frequency is higher, and the larger the junction capacitance is, the smaller it is.

As shown in FIG. 1, a first series circuit including two first diodes Da and a second series circuit including two second diodes Db are connected between two communication conductors 2a and 2b. A first series circuit and a second series circuit are also connected between two communication conductors 3a and 3b. Therefore, the communication characteristics for communication via communication line 2 depend on the magnitude of the junction capacitance of the two first diodes Da included in the first series circuit between the two communication conductors 2a and 2b and the magnitude of the junction capacitance of the two second diodes Db included in the second series circuit between the two communication conductors 2a and 2b. The communication characteristics for communication via communication line 3 depend on the magnitude of the junction capacitance of the two first diodes Da included in the first series circuit between the two communication conductors 3a and 3b and the magnitude of the junction capacitance of the two second diodes Db included in the second series circuit between the two communication conductors 3a and 3b.

The state in which the power supply circuit 11 is transmitting power is referred to as the "usage state." In the discharge device 12 in the usage state, a reverse bias voltage is applied to the two first diodes Da and the two second diodes Db. The communication characteristics of the discharge device 12 in the usage state differ from the communication characteristics of the discharge device 12 in a state in which a reverse bias voltage is not applied to all of the first diodes Da and all of the second diodes Db. It is preferable for the designer of the communication system 1 to understand the communication characteristics of the discharge device 12 in a state close to the usage state. The following describes a method for measuring the communication characteristics of the discharge device 12 in a state close to the usage state.

Figure 3 is an explanatory diagram of a method for measuring communication characteristics. In this method, the person measuring first connects a capacitor C between two terminals T1 and T2, as shown in the upper part of Figure 3. In this state, the person measuring connects a first communication device A1 and a second communication device A2 to communication lines 2 and 3 of the discharge device 12. After the connection is made, the power supply circuit 11 sends power to the power receiving circuit 13 via the discharge device 12, and the capacitor C is charged.

Current flows from one of the communication conductors 2a, 2b through the first diode Da, terminal T1, capacitor C, terminal T2, second diode Db, and one of the communication conductors 3a, 3b in this order. After capacitor C is charged, the measurer removes first communication device A1 and second communication device A2 from the discharge device 12. In this state, as shown in the lower part of Figure 3, capacitor C applies a reverse bias voltage to the four first diodes Da. Capacitor C applies a voltage between the two terminals T1 and T2. Capacitor C functions as a voltage application unit.

After disconnecting the first communication device A1 and the second communication device A2 from the discharge device 12, the measurer connects the first measuring device 61 and the second measuring device 62 to the communication lines 2 and 3 of the discharge device 12. The first measuring device 61 and the second measuring device 62 send and receive differential signals via the communication lines 2 and 3 that run inside the discharge device 12, and measure the communication characteristics related to the communication via each of the communication lines 2 and 3. The first measuring device 61 and the second measuring device 62 together function as a measurement unit.

The state in which the communication characteristics are measured is referred to as the measurement state. The upper and lower parts of Figure 3 show the discharge device 12 in use and measurement states, respectively. In the use state of the discharge device 12, a reverse bias voltage is applied to the two diodes in one of the first and second series circuits for each of the communication lines 2 and 3, while no reverse bias voltage is applied to the two diodes in the other series circuit. In the measurement state of the discharge device 12, a reverse bias voltage is also applied to the two diodes in one of the first and second series circuits for each of the communication lines 2 and 3, while no reverse bias voltage is applied to the two diodes in the other series circuit. Therefore, the measurement state for each of the communication lines 2 and 3 is close to the use state. Therefore, the communication characteristics measured by the first meter 61 and the second meter 62 are the communication characteristics of the discharge device 12 in a state close to the use state.

Figure 4 is an explanatory diagram of the contents of the communication characteristics. The first measuring instrument 61 and the second measuring instrument 62 measure the loss caused by propagation for each of the multiple frequency components that make up the differential signal propagating through the communication line 2. Similarly, the first measuring instrument 61 and the second measuring instrument 62 measure the loss caused by propagation for each of the multiple frequency components that make up the differential signal propagating through the communication line 3. The first measuring instrument 61 or the second measuring instrument 62 creates a graph showing the relationship between frequency and loss, as shown on the left side of Figure 4, and displays the created graph.

The first measuring device 61 and the second measuring device 62 measure the reflectivity of each of the multiple frequency components that make up the differential signal propagating through the communication line 2. The reflectivity of one frequency component is a value obtained by dividing the intensity of the wave propagating in the transmission direction by the intensity of the wave propagating in the opposite direction. With respect to the communication line 2, the transmission direction is the direction from the first communication device A1 to the second communication device A2, i.e., the rightward direction in Figure 3. The reverse direction is the direction from the second communication device A2 to the first communication device A1, i.e., the leftward direction in Figure 3.

The first measuring device 61 and the second measuring device 62 measure the reflectivity of each of the multiple frequency components that make up the differential signal propagating through the communication line 3. With respect to the communication line 3, the direction from the second communication device A2 to the first communication device A1 is the transmission direction. The reverse direction is the direction from the first communication device A1 to the second communication device A2. The first measuring device 61 or the second measuring device 62 creates a graph showing the relationship between frequency and reflectivity, as shown on the right side of Figure 4, and displays the created graph.

As described above, loss and reflectance are each a type of communication characteristic. The first measuring device 61 and the second measuring device 62 may further measure crosstalk as a communication characteristic. A differential signal is transmitted via communication line 2 while no signal is being transmitted via communication line 3. At this time, the intensity of the noise generated on communication line 3 is the crosstalk. When a differential signal is transmitted via communication line 2, electromagnetic waves generated from communication line 2 interfere with communication line 3, generating noise on communication line 3. Regarding crosstalk, the intensity of the noise for each of multiple frequency components may be indicated. Similarly, a differential signal is transmitted via communication line 3 while no signal is being transmitted via communication line 2. In this case, the first measuring device 61 and the second measuring device 62 may further measure crosstalk, which is the intensity of the noise generated on communication line 2.

Note that for each of communication lines 2 and 3, the direction in which differential signals are transmitted is not limited to one direction, and differential signals may be transmitted in both directions. Therefore, for communication line 2, first measuring device 61 and second measuring device 62 may measure not only the communication characteristics when differential signals are transmitted in the transmission direction, but also the communication characteristics when differential signals are transmitted in the reverse direction. Similarly, for communication line 3, first measuring device 61 and second measuring device 62 may measure not only the communication characteristics when differential signals are transmitted in the transmission direction, but also the communication characteristics when differential signals are transmitted in the reverse direction.

In the above-described method for measuring communication characteristics, the charged capacitor C applies a reverse bias voltage to the four first diodes Da, so that the first measuring instrument 61 and the second measuring instrument 62 can measure the communication characteristics of the discharge device 12 when the state is close to the usage state.
The system including the discharge device 12, the first measuring device 61, the second measuring device 62 and the capacitor C functions as a measuring system.

(Embodiment 2)
In the first embodiment, the power supply circuit 11 of the first communication device A1 sends power to the power receiving circuit 13 of the second communication device A2 via four communication conductors 2a, 2b, 3a, and 3b. However, the power supply circuit 11 may send power to the power receiving circuit 13 via four conductors other than the four communication conductors 2a, 2b, 3a, and 3b.
The following describes the differences between embodiment 2 and embodiment 1. Except for the configuration described below, the other configurations are common to embodiment 1, and therefore the same reference numerals as in embodiment 1 are used for the components common to embodiment 1, and the description thereof will be omitted.

Figure 5 is a circuit diagram of the discharge device 12 in use in embodiment 2. Figure 6 is a circuit diagram of the power supply circuit 11. Figure 7 is a circuit diagram of the power receiving circuit 13. In embodiment 2, in addition to the two communication lines 2 and 3, two power supply lines 7 and 8 used for power supply run through the discharge device 12. As shown in Figures 5 to 7, the first communication circuit 10 is connected to the second communication circuit 14 via the two communication lines 2 and 3, as in embodiment 1. The power supply circuit 11 in embodiment 2 is further connected to the power receiving circuit 13 via the two power supply lines 7 and 8. The power supply line 7 includes two power supply conductors 7a and 7b. The power supply line 8 includes two power supply conductors 8a and 8b. Each of the power supply lines 7 and 8 is, for example, a twisted pair wire. In this case, the two power supply conductors 7a and 7b are twisted together. The two power supply conductors 8a and 8b are also twisted together.

As shown in FIG. 6, one end of power supply conductor 7a is connected to one end of power supply conductor 7b. The positive terminal of DC power supply 41 is connected midway to the connecting line connecting one ends of the two power supply conductors 7a and 7b. One end of power supply conductor 8a is connected to one end of power supply conductor 8b. The negative terminal of DC power supply 41 is connected midway to the connecting line connecting one ends of the two power supply conductors 8a and 8b. The DC power supply 41 is not connected to communication transformers 42 and 43.

As shown in FIG. 7, the power receiving circuit 13 includes a DC-DC converter 51 and two communication transformers 52 and 53, similar to the first embodiment. The power receiving circuit 13 in the second embodiment further includes a first bridge circuit G1 and a second bridge circuit G2. The first bridge circuit G1 and the second bridge circuit G2 each include four circuit diodes H1, H2, H3, and H4. In the first bridge circuit G1 and the second bridge circuit G2, the anode of the circuit diode H1 is connected to the cathode of the circuit diode H2. The cathode of the circuit diode H1 is connected to the cathode of the circuit diode H3. The anode of the circuit diode H2 is connected to the anode of the circuit diode H4. The anode of the circuit diode H3 is connected to the cathode of the circuit diode H4. The first bridge circuit G1 and the second bridge circuit G2 are each configured similarly to a diode bridge circuit that performs full-wave rectification of AC voltage. FIG. 7 does not indicate whether a reverse bias voltage is applied to the circuit diodes H1, H2, H3, and H4.

With regard to the first bridge circuit G1, the connection node between the circuit diodes H1 and H2 is connected midway through the winding 52a of the communication transformer 52. The connection node between the circuit diodes H3 and H4 is connected midway through the winding 53a of the communication transformer 53. The connection node between the circuit diodes H1 and H3 is connected to the first input terminal of the DCDC converter 51. The connection node between the circuit diodes H2 and H4 is connected to the second input terminal of the DCDC converter 51.

The other end of power supply conductor 7a is connected to the other end of power supply conductor 7b. Similarly, the other end of power supply conductor 8a is connected to the other end of power supply conductor 8b. For the second bridge circuit G2, the connection node between circuit diodes H1 and H2 is connected midway along the connection line connecting the other ends of the two power supply conductors 7a and 7b. The connection node between circuit diodes H3 and H4 is connected midway along the connection line connecting the other ends of the two power supply conductors 8a and 8b. The connection node between circuit diodes H1 and H3 is connected to the first input terminal of the DCDC converter 51. The connection node between circuit diodes H2 and H4 is connected to the second input terminal of the DCDC converter 51.

As in embodiment 1, assume that a DC power supply 41 is connected between windings 42b and 43b of the power supply circuit 11. When the potential of communication conductors 2a and 2b is higher than the potential of communication conductors 3a and 3b, current flows through circuit diode H1, DCDC converter 51, and circuit diode H4 in that order. Therefore, with respect to DCDC converter 51, the potential of the first input terminal is higher than the potential of the second input terminal. When the potential of communication conductors 3a and 3b is higher than the potential of communication conductors 2a and 2b, current flows through circuit diode H3, DCDC converter 51, and circuit diode H2 in that order. Even in this case, with respect to DCDC converter 51, the potential of the first input terminal is higher than the potential of the second input terminal. Therefore, regardless of whether the electrode of DC power supply 41 connected to winding 42b is positive, the voltage at the first input terminal is positive, with the potential at the second input terminal as the reference potential. The DC-DC converter 51 operates normally regardless of whether the electrode of the DC power supply 41 connected to the winding 42b is positive or not.

In embodiment 2, the DC power supply 41 is not connected between the windings 42b and 43b of the power supply circuit 11. However, when the DC power supply 41 is connected between the windings 42b and 43b of the power supply circuit 11, the DCDC converter 51 supplies power to the second communication circuit 14, as in embodiment 1.

In embodiment 2, the potential of power supply conductors 7a and 7b is higher than the potential of power supply conductors 8a and 8b. Therefore, current flows through circuit diode H1, DCDC converter 51, and circuit diode H4 in that order. Therefore, with respect to DCDC converter 51, the potential of the first input terminal is higher than the potential of the second input terminal. Assume that the positive electrode of DC power supply 41 is connected to the connection node between one end of power supply conductors 8a and 8b, and the negative electrode of DC power supply 41 is connected to the connection node between one end of power supply conductors 7a and 7b.

In this case, the potential of the power supply conductors 8a and 8b is higher than the potential of the power supply conductors 7a and 7b. In this case, current flows through the circuit diode H3, the DCDC converter 51, and the circuit diode H2 in that order. Even in this case, the potential of the first input terminal of the DCDC converter 51 is higher than the potential of the second input terminal. Therefore, regardless of the connection of the positive and negative terminals of the DC power supply 41, the voltage of the first input terminal is a positive voltage, with the potential of the second input terminal as the reference potential. The DCDC converter 51 operates normally regardless of the connection of the positive and negative terminals of the DC power supply 41.

The DC-DC converter 51 transforms the voltage applied between the first input terminal and the second input terminal into a target voltage and applies the target voltage to the second communication circuit 14. This supplies power to the second communication circuit 14.

In the first embodiment, the power supply circuit 11 transmits power via the communication lines 2 and 3. In the second embodiment, the power supply circuit 11 transmits power to the power receiving circuit 13 via the power supply lines 7 and 8, similar to the power supply via the communication lines 2 and 3 in the first embodiment. Current flows from the positive pole of the DC power supply 41 to the DCDC converter 51 via two power supply conductors 7a and 7b. In each of the power supply conductors 7a and 7b, current flows from the power supply circuit 11 toward the power receiving circuit 13. From the DCDC converter 51, current flows to the negative pole of the DC power supply 41 via two power supply conductors 8a and 8b. In each of the power supply conductors 8a and 8b, current flows from the power receiving circuit 13 toward the power supply circuit 11. As a result, the output voltage of the DC power supply 41 is input to the DCDC converter 51.

Let's assume that the positive electrode of the DC power supply 41 is connected to the connection node between one end of the power supply conductors 8a and 8b, and the negative electrode of the DC power supply 41 is connected to the connection node between one end of the power supply conductors 7a and 7b. In this case, current flows from the positive electrode of the DC power supply 41 to the DCDC converter 51 via the two power supply conductors 8a and 8b. In each of the power supply conductors 8a and 8b, current flows from the power supply circuit 11 toward the power receiving circuit 13. From the DCDC converter 51, current flows to the negative electrode of the DC power supply 41 via the two power supply conductors 7a and 7b. In each of the power supply conductors 7a and 7b, current flows from the power receiving circuit 13 toward the power supply circuit 11. As a result, the output voltage of the DC power supply 41 is input to the DCDC converter 51.

As shown in FIG. 5, the discharge device 12 has eight first diodes Da and eight second diodes Db. The discharge conductor B is different from the communication conductors 2a, 2b, 3a, and 3b and the power supply conductors 7a, 7b, 8a, and 8b. The anodes of the eight first diodes Da are connected to four communication conductors 2a, 2b, 3a, and 3b and four power supply conductors 7a, 7b, 8a, and 8b. The cathodes of the eight second diodes Db are connected to four communication conductors 2a, 2b, 3a, and 3b and four power supply conductors 7a, 7b, 8a, and 8b. The cathodes of the eight first diodes Da are connected to the first electrode of the discharger F. The anodes of the eight second diodes Db are connected to the second electrode of the discharger F.

In embodiment 2, one of the conductors included in the communication conductors 2a, 2b, 3a, and 3b and the power supply conductors 7a, 7b, 8a, and 8b is referred to as the target conductor. The target conductor may be any of the communication conductors 2a, 2b, 3a, and 3b and the power supply conductors 7a, 7b, 8a, and 8b. As in embodiment 1, when the absolute value of the voltage of the target conductor exceeds a predetermined voltage, the discharger F passes current through the discharge conductor B. As a result, the absolute values of the voltages of the four communication conductors 2a, 2b, 3a, and 3b and the four power supply conductors 7a, 7b, 8a, and 8b, with the ground potential as the reference potential, are maintained below the predetermined voltage.

For example, the two communication lines 2 and 3 and the two power supply lines 7 and 8 between the power supply circuit 11 and the discharge device 12 are located outdoors. In this case, when lightning strikes, there is a possibility that the absolute value of the voltage of the target conductor, with the ground potential as the reference potential, will rise. The discharge device 12 maintains the absolute value of the voltage of the target conductor, with the ground potential as the reference potential, below a predetermined voltage, thereby protecting the second communication device A2 from the application of an overvoltage whose absolute value exceeds the predetermined voltage.

Figure 5 shows the discharge device 12 in use. With respect to the output voltage of the DC power supply 41, the potential of the power supply conductors 7a and 7b is higher than the potential of the power supply conductors 8a and 8b. Therefore, a reverse bias voltage is applied to the two second diodes Db connected to the power supply conductors 7a and 7b, respectively, and the two first diodes Da connected to the power supply conductors 8a and 8b, respectively.

The voltage of the power supply conductors 7a and 7b is applied as a reverse bias voltage to the four first diodes Da connected to each of the communication conductors 2a, 2b, 3a, and 3b. For each of the communication lines 2 and 3 and the power supply line 8, a reverse bias voltage is applied to the two first diodes Da included in the first series circuit. No reverse bias voltage is applied to the two second diodes Db included in the second series circuit. For the power supply line 7, a reverse bias voltage is applied to the two second diodes Db included in the second series circuit. No reverse bias voltage is applied to the two first diodes Da included in the first series circuit.

When the potential of the power supply conductors 8a and 8b is higher than the potential of the power supply conductors 7a and 7b, a reverse bias voltage is applied to the two second diodes Db connected to the power supply conductors 8a and 8b, respectively, and to the two first diodes Da connected to the power supply conductors 7a and 7b, respectively.

The voltage of the power supply conductors 8a and 8b is applied as a reverse bias voltage to the four first diodes Da connected to each of the communication conductors 2a, 2b, 3a, and 3b. For each of the communication lines 2 and 3 and the power supply line 7, a reverse bias voltage is applied to the two first diodes Da included in the first series circuit. No reverse bias voltage is applied to the two second diodes Db included in the second series circuit. For the power supply line 8, a reverse bias voltage is applied to the two second diodes Db included in the second series circuit. No reverse bias voltage is applied to the two first diodes Da included in the first series circuit.

Figure 8 is a circuit diagram of the discharge device 12 in measurement mode. In embodiment 2, the measurer also connects capacitor C between terminals T1 and T2, and connects the first communication device A1 and the second communication device A2 to the communication lines 2 and 3 and the power supply lines 7 and 8 of the discharge device 12. As a result, the power supply circuit 11 of the first communication device A1 charges capacitor C, as in embodiment 1. After capacitor C is charged, the measurer disconnects the first communication device A1 and the second communication device A2 from the discharge device 12. In this state, as shown in Figure 8, capacitor C applies a reverse bias voltage to the eight first diodes Da.

After disconnecting the first communication device A1 and the second communication device A2 from the discharge device 12, the measurer connects the first measuring device 61 and the second measuring device 62 to the communication lines 2 and 3 and the power supply lines 7 and 8 of the discharge device 12. The first measuring device 61 and the second measuring device 62 send and receive differential signals via the communication lines 2 and 3 that run inside the discharge device 12, and measure the communication characteristics related to the communication via each of the communication lines 2 and 3.

When the discharge device 12 is in use, a reverse bias voltage is applied to the two diodes in one of the first and second series circuits for the communication lines 2 and 3 and the power feed lines 7 and 8, respectively, and no reverse bias voltage is applied to the two diodes in the other series circuit. When the discharge device 12 is in the measurement state, a reverse bias voltage is applied to the two diodes in one of the first and second series circuits for the communication lines 2 and 3 and the power feed lines 7 and 8, respectively, and no reverse bias voltage is applied to the two diodes in the other series circuit. Therefore, the measurement state is close to the usage state for the communication lines 2 and 3 and the power feed lines 7 and 8, respectively. Therefore, the communication characteristics measured by the first measuring device 61 and the second measuring device 62 are the communication characteristics of the discharge device 12 in a state close to the usage state.

The method for measuring communication characteristics in embodiment 2 achieves the same effects as the method for measuring communication characteristics in embodiment 1. In embodiment 2, the system including the discharge device 12, first measuring device 61, second measuring device 62, and capacitor C also functions as a measurement system.

In addition, in embodiment 2, differential signals may be transmitted via power feeders 7 and 8. In this case, first measuring device 61 and second measuring device 62 measure the communication characteristics related to communication via communication lines 2 and 3 and power feeders 7 and 8, respectively.

(Embodiment 3)
In the first embodiment, the power supply circuit 11 charges the capacitor C. However, the device that charges the capacitor C may be a device different from the power supply circuit 11.
The following describes the differences between embodiment 3 and embodiment 1. Except for the configuration described below, the configuration is the same as embodiment 1. Therefore, the components that are the same as embodiment 1 are given the same reference numerals as embodiment 1, and the description thereof will be omitted.

Figure 9 is a circuit diagram of the discharge device 12 in a measurement state in embodiment 3. The discharge device 12 in embodiment 3 includes a charging circuit 9 in addition to the components of the discharge device 12 in embodiment 1. The charging circuit 9 includes charging diodes 91 and 92, a resistor 93, a DC power supply 94, and a switch 95. The cathode of the charging diode 91 is connected to the first electrode of the discharger F. The anode of the charging diode 91 is connected to one end of the resistor 93. The other end of the resistor 93 is connected to the positive electrode of the DC power supply 94. The negative electrode of the DC power supply 94 is connected to one end of the switch 95. The other end of the switch 95 is connected to the cathode of the charging diode 92. The anode of the charging diode 92 is connected to the second electrode of the discharger F. Note that the location where the charging circuit 9 is located is not limited to inside the discharge device 12, and it may be located outside the discharge device 12.

Switch 95 is normally off. When measuring communication characteristics in embodiment 3, the measurer connects capacitor C between terminals T1 and T2 and connects first measuring device 61 and second measuring device 62 to communication lines 2 and 3 of discharge device 12. Next, the measurer switches switch 95 from off to on. This causes current to flow from the positive terminal of DC power supply 94 through resistor 93, charging diode 91, terminal T1, capacitor C, terminal T2, charging diode 92, switch 95, and the negative terminal of DC power supply 94 in this order. This charges capacitor C. After capacitor C is charged, the measurer switches switch 95 off. In this state, capacitor C applies a reverse bias voltage to the four first diodes Da, as shown in Figure 9.

As in embodiment 1, the first measuring device 61 and the second measuring device 62 measure the communication characteristics of the communication on each of the communication lines 2 and 3 while the capacitor C is applying a reverse bias voltage to the four first diodes Da.

The method for measuring communication characteristics in embodiment 3 achieves the same effects as the method for measuring communication characteristics in embodiment 1. In embodiment 2, too, a system including the discharge device 12, first measuring device 61, second measuring device 62, and capacitor C functions as a measurement system.

In addition, in embodiment 3, even if capacitor C is not connected between terminals T1 and T2, the first measuring device 61 and second measuring device 62 can measure communication characteristics with a reverse bias voltage applied to the four first diodes Da. In this case, with capacitor C not connected between terminals T1 and T2, the measurer switches switch 95 from off to on. In this state, the potential of terminal T1 is higher than the potential of terminal T2. A reverse bias voltage is applied to the four first diodes Da. The first measuring device 61 and second measuring device 62 measure communication characteristics with switch 95 on.

When the switch 95 is on, the charging circuit 9 applies a voltage between the two terminals T1 and T2. In a configuration in which the capacitor C is not connected, the charging circuit 9 functions as a voltage applying section.
There is no problem with the configuration of the charging circuit 9 as long as it is configured to apply a voltage between the two terminals T1 and T2. Therefore, the switch 95 of the charging circuit 9 may be always on. Furthermore, the charging circuit 9 may be configured without the switch 95. In this case, the negative electrode of the DC power supply 41 is connected to the cathode of the charging diode 92.

In embodiment 2, the discharge device 12 may be configured to include a charging circuit 9, as in embodiment 3. In this case, as in embodiment 3, it is not necessary to connect the first communication device A1 and the second communication device A2 to charge the capacitor C. In addition, the communication characteristics may be measured without connecting the capacitor C.

In embodiments 1 to 3, the number of communication lines is not limited to two and may be one or three or more. Furthermore, in a configuration in which a capacitor C is connected, the capacitor C may be constantly connected between terminals T1 and T2. In this case, the capacitor C is included in the discharge device 12.

In embodiments 1 to 3, there is no problem if discharger F operates as follows. When the voltage between the first electrode and discharge conductor B exceeds the threshold voltage, current flows through the first electrode and discharge conductor B. When the voltage between the second electrode and discharge conductor B exceeds the threshold voltage, current flows through the second electrode and discharge conductor B. Therefore, discharger F may be configured such that a first element is connected between the first electrode and discharge conductor B, and a second element is connected between the second electrode and discharge conductor B. The first element and second element may each be a two-terminal discharge tube, Zener diode, varistor, or the like.

The technical features (constituent elements) described in the first to third embodiments can be combined with each other, and by combining them, new technical features can be formed.
The disclosed embodiments 1 to 3 are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the meaning described above, and is intended to include all modifications within the meaning and scope of the claims.

2a, 2b, 3a, 3b: communication conductor; 9: charging circuit (voltage application section); 11: power supply circuit; 12: discharge device; 13: power receiving circuit; C: capacitor (voltage application section); 61: first meter (part of the measurement section); 62: second meter (part of the measurement section); Da: first diode; Db: second diode; F: discharger

Claims (5)

A method for measuring characteristics of a discharge device including: a plurality of first diodes, each having an anode connected to a plurality of conductors; a plurality of second diodes, each having a cathode connected to the plurality of conductors; and a discharger, having a first electrode connected to the cathodes of the plurality of first diodes and a second electrode connected to the anodes of the plurality of second diodes, which causes a current to flow through a second conductor different from the plurality of conductors when an absolute value of a voltage of the conductors reaches or exceeds a predetermined voltage,
applying a voltage between the first electrode and the second electrode;
measuring communication characteristics relating to communication via two conductors included in the plurality of conductors. connecting a capacitor between the first electrode and the second electrode;
charging the capacitor;
The method of claim 1 , wherein the capacitor applies a voltage between the first electrode and the second electrode. The measurement method according to claim 1 or 2, further comprising the step of measuring a loss occurring due to propagation for each of a plurality of frequency components constituting a signal propagating through the two conductors. The measurement method according to claim 1 , further comprising the step of measuring the reflectance of each of a plurality of frequency components that constitute a signal propagating through the two conductors. a discharge device including: a plurality of first diodes, each having an anode connected to a plurality of conductors; a plurality of second diodes, each having a cathode connected to the plurality of conductors; and a discharger, each having a first electrode connected to the cathodes of the plurality of first diodes and a second electrode connected to the anodes of the plurality of second diodes, which causes a current to flow through a second conductor different from the plurality of conductors when the absolute value of the voltage of the conductors becomes equal to or greater than a predetermined voltage;
a voltage application unit that applies a voltage between the first electrode and the second electrode;
a measurement unit that measures communication characteristics related to communication via two conductors included in the plurality of conductors.