Test method and test system

Abstract

To provide a test method capable of confirming whether or not a protection device is operated normally, and a test system.SOLUTION: A first protection device 12 and a second protection device 13 are respectively connected in the middle of a communication line which is connected between a feeder (first electric apparatus) 11 and a camera (second electric apparatus) 14. Each of the first protection device 12 and the second protection device 13 causes a current to flow via a lead wire B2 for discharge in a case where an absolute value of the voltage of a lead wire for communication included in the communication line is equal to or higher than a predetermined voltage. Thus, the feeder 11 and the camera 14 are protected from application of overvoltage. In a test of the second protection device 13, a surge generation device 15 applies a surge voltage to the lead wire B2 for discharge of the second protection device 13. During an application period in which the surge voltage is applied, an information processing terminal 10 receives data transmitted from the camera 14 toward the feeder 11 via at least one of communication lines 2 and 3.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a testing method and a testing system. [Background technology]

[0002] Patent Document 1 discloses a protection device that protects communication equipment from the application of an overvoltage whose absolute value exceeds a predetermined voltage. Two communication conductors are connected to the communication equipment. In the protection device, discharge tubes are connected to each of the two conductors. The discharge tubes are further connected to the ground. For example, if a surge voltage is applied to a conductor located outdoors due to lightning, the absolute value of the voltage of the conductor increases. If the absolute value of the voltage of the conductor exceeds a predetermined voltage, current flows through the discharge tube and the ground. As a result, the absolute value of the voltage of the conductor is maintained at a voltage below the predetermined voltage. The communication equipment is protected from the application of an overvoltage. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2-55524 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 does not consider a test method for checking whether the protection device is operating normally.

[0005] The present disclosure has been made in consideration of the above circumstances, and its purpose is to provide a test method and test system that can confirm whether a protection device is operating normally. [Means for solving the problem]

[0006] A testing method according to one aspect of the present disclosure includes the steps of applying a surge voltage whose absolute value exceeds a predetermined voltage to the discharge conductor of one of a first protection device and a second protection device, which are arranged midway along a communication line connected between a first electrical device and a second electrical device and which protect the first electrical device and the second electrical device, respectively, from the application of an overvoltage whose absolute value exceeds a predetermined voltage by passing a current through a discharge conductor different from the communication conductor when the absolute value of the voltage of the communication conductor included in the communication line becomes equal to or greater than a predetermined voltage; and receiving a signal transmitted from the second electrical device via the communication line to the first electrical device during an application period in which the surge voltage is applied, or transmitting a signal to the second electrical device via the communication line during the application period.

[0007] A test system according to one embodiment of the present disclosure includes a first electrical device, a second electrical device connected to the first electrical device by a communication line, a first protection device and a second protection device arranged midway along the communication line, which protect the first electrical device and the second electrical device, respectively, from application of an overvoltage whose absolute value exceeds a predetermined voltage by passing a current through a discharge conductor different from the communication conductor when the absolute value of the voltage of the communication conductor included in the communication line becomes equal to or greater than a predetermined voltage, a surge generating device that applies a surge voltage whose absolute value exceeds the predetermined voltage to the discharge conductor of one of the first protection device and the second protection device, and an information processing terminal that receives a signal transmitted from the second electrical device via the communication line to the first electrical device during an application period in which the surge generating device is applying the surge voltage, or transmits a signal to the second electrical device via the communication line during the application period. [Effects of the Invention]

[0008] According to the above aspect, it is possible to check whether the protection device is operating normally. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a configuration of a main part of a test system according to a first embodiment. [Figure 2] FIG. 2 is a circuit diagram of a first protection device and a second protection device. [Figure 3] FIG. 10 is a block diagram showing the configuration of a main part of a test system according to a second embodiment. [Figure 4] FIG. 11 is a block diagram showing the configuration of a main part of a test system according to a third embodiment. [Figure 5] FIG. 10 is a block diagram showing the configuration of a main part of a test system according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the present disclosure will be described in detail with reference to the drawings showing embodiments thereof. (Embodiment 1) 1 is a block diagram showing the main configuration of a test system 1 in embodiment 1. The test system 1 includes an information processing terminal 10, a power supply device 11, a first protection device 12, a second protection device 13, a camera 14, a surge generator 15, and four communication cables A1, A2, A3, and A4. The information processing terminal 10 is, for example, a personal computer. The information processing terminal 10, the power supply device 11, and the camera 14 are electrical devices. Each of the communication cables A1, A2, A3, and A4 is, for example, a LAN cable. LAN is an abbreviation for Local Area Network.

[0011] The information processing terminal 10 is connected to a power supply device 11 via a communication cable A1. The power supply device 11 is connected to a first protection device 12 via a communication cable A2. The first protection device 12 is connected to a second protection device 13 via a communication cable A3. The second protection device 13 is connected to a camera 14 via a communication cable A4. The first protection device 12 is connected to a discharge conductor B1. The discharge conductor B1 is grounded. The grounding is achieved, for example, by connection to the earth. The power supply device 11 is connected midway along the discharge conductor B1.

[0012] The second protection device 13 is connected to the surge generator 15 by a discharge conductor B2. The camera 14 is connected midway along the discharge conductor B2. The surge generator 15 is grounded. The power supply 11 is further connected to a power source 16. The power source 16 is, for example, an outlet. The power source 16 supplies AC power to the power supply 11.

[0013] The information processing terminal 10 is connected to the camera 14 by two communication lines 2 and 3 (see FIG. 2). The communication lines 2 and 3 each pass through the interior of the communication cable A1, the power supply device 11, the communication cable A2, the first protection device 12, the communication cable A3, the second protection device 13, and the communication cable A4. Therefore, the power supply device 11 is connected to the camera 14 by the two communication lines 2 and 3. The first protection device 12 and the second protection device 13 are disposed midway along the two communication lines 2 and 3 disposed between the power supply device 11 and the camera 14. The information processing terminal 10 communicates with the camera 14 via the communication lines 2 and 3.

[0014] The communication line 2 includes two communication conductors 2a and 2b. One of the information processing terminal 10 and the camera 14 transmits a signal via the communication line 2. The other of the information processing terminal 10 and the camera 14 receives the signal via the communication line 2. Similarly, the communication line 3 includes two communication conductors 3a and 3b. One of the information processing terminal 10 and the camera 14 transmits a signal via the communication line 3. The other of the information processing terminal 10 and the camera 14 receives the signal via the communication line 3. The communication conductors 2a, 2b, 3a, and 3b are different from the discharge conductors B1 and B2.

[0015] A transmitter that transmits a signal via communication line 2 applies a voltage to communication conductors 2a and 2b and adjusts the voltage difference between communication conductors 2a and 2b to various signal levels. This causes a differential signal to be transmitted from the transmitter to a receiver that receives the signal. Similarly, a transmitter that transmits a signal via communication line 3 applies a voltage to communication conductors 3a and 3b and adjusts the voltage difference between communication conductors 3a and 3b to various signal levels. This causes a differential signal to be transmitted from the transmitter to the receiver.

[0016] The camera 14 is, for example, a security camera. The camera 14 is installed, for example, outdoors. The camera 14 periodically captures images of the outdoors. The images captured by the camera 14 are still images or moving images. Every time the camera 14 captures an image, it transmits a differential signal containing image data of the captured image to the information processing terminal 10 via the communication line 2 or the communication line 3. The information processing terminal 10 has a display. Every time the information processing terminal 10 receives a differential signal from the camera 14, it displays an image of the image data contained in the received differential signal on the display.

[0017] Power supply device 11 converts AC power supplied from power source 16 into DC power and supplies the converted DC power to camera 14 via communication lines 2 and 3. When power is being supplied to camera 14, current flows from power supply device 11 to camera 14 via communication conductors 2a and 2b, and returns from camera 14 to power supply device 11 via communication conductors 3a and 3b. Each of communication conductors 2a, 2b, 3a, and 3b functions not only as a conductor for communication but also as a power supply conductor for supplying power to camera 14.

[0018] The power supply device 11 supplies power via, for example, PoE. PoE is an abbreviation for Power over Ethernet. Ethernet is a registered trademark. PoE power supply is power supply via a LAN cable.

[0019] 2 is a circuit diagram of the first protection device 12 and the second protection device 13. As described above, the communication lines 2 and 3 pass through the first protection device 12, the communication cable A3, and the second protection device 13, respectively. The second protection device 13 has the same configuration as the first protection device 12. Each of the first protection device 12 and the second protection device 13 is, for example, an SPD (Surge Protective Device).

[0020] Each of the first protection device 12 and the second protection device 13 has four first diodes Da, four second diodes Db, and a discharger F. The discharger F is a so-called arrester. A discharge conductor B1 is connected to the discharger F of the first protection device 12. A discharge conductor B2 is connected to the discharger F of the second protection device 13. Each discharger F has a first electrode and a second electrode.

[0021] In the first protection device 12, the anodes of the four first diodes Da are connected to the middle of 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 cathodes of the four second diodes Db are connected to the middle of the four communication conductors 2a, 2b, 3a, and 3b. The anodes of the four second diodes Db are connected to the second electrode of the discharger F. The connections of the four first diodes Da, the four second diodes Db, and the discharger F in the second protection device 13 are similar to the connections of the four first diodes Da, the four second diodes Db, and the discharger F in the first protection device 12.

[0022] In the discharger F of the first protection device 12, when the absolute value of the voltage between the first electrode and the discharge conductor B1 exceeds a certain voltage threshold, an arc is generated between the first electrode and the discharge conductor B1, and a current flows through the first electrode and the discharge conductor B1. When the absolute value of the voltage between the second electrode and the discharge conductor B1 exceeds the voltage threshold, an arc is generated between the second electrode and the discharge conductor B1, and a current flows through the second electrode and the discharge conductor B1.

[0023] Similarly, in discharger F of second protection device 13, when the absolute value of the voltage between the first electrode and discharge conductor B2 is equal to or greater than the voltage threshold, an arc is generated between the first electrode and discharge conductor B2, and current flows through the first electrode and discharge conductor B2. When the absolute value of the voltage between the second electrode and discharge conductor B2 is equal to or greater than the voltage threshold, an arc is generated between the second electrode and discharge conductor B2, and current flows through the second electrode and discharge conductor B1.

[0024] Assume that the voltage of one target conductor among the four communication conductors 2a, 2b, 3a, and 3b increases. The voltage of the target conductor is a voltage with the ground potential as the reference potential. If grounding is achieved by connecting to the ground, the ground potential is the potential of the earth. If the voltage of the target conductor increases near the first protection device 12, and the absolute value of the voltage of the target conductor exceeds a predetermined voltage, the absolute value of the voltage between the discharge conductor B1 and the first electrode of the discharger F in the first protection device 12 exceeds a voltage threshold. As a result, current flows from the target conductor to the first diode Da, the discharger F, and the discharge conductor B1 in this order. As a result, the absolute value of the voltage of the target conductor is maintained below the predetermined voltage.

[0025] Assume that the voltage of one target conductor among the four communication conductors 2a, 2b, 3a, and 3b drops to a voltage below 0 V. In this case, when the absolute value of the voltage of the target conductor becomes equal to or greater than a predetermined voltage, the absolute value of the voltage between the discharge conductor B1 and the second electrode of the discharger F in the first protection device 12 becomes equal to or greater than the voltage threshold. As a result, current flows in the order of discharge conductor B1, discharger F, second diode Db, and the target conductor. As a result, the absolute value of the voltage of the target conductor is maintained below the predetermined voltage. As described above, first protection device 12 protects power supply device 11 from application of an overvoltage exceeding a predetermined voltage. Power supply device 11 functions as a first electric device.

[0026] Similarly, when the voltage of the target conductor increases near the second protection device 13, and the absolute value of the voltage of the target conductor exceeds a predetermined voltage, the absolute value of the voltage between the discharge conductor B2 and the first electrode of the discharger F in the second protection device 13 exceeds the voltage threshold. As a result, current flows from the target conductor to the first diode Da, the discharger F, and the discharge conductor B1 in that order. As a result, the absolute value of the voltage of the target conductor is maintained below the predetermined voltage.

[0027] When the voltage of one target conductor included in the four communication conductors 2a, 2b, 3a, 3b drops to a voltage below 0 V, and the absolute value of the voltage of the target conductor becomes equal to or greater than a predetermined voltage, the absolute value of the voltage between the discharge conductor B2 and the second electrode of the discharger F in the second protection device 13 becomes equal to or greater than the voltage threshold. As a result, current flows in the order of discharge conductor B1, discharger F, second diode Db, and the target conductor. As a result, the absolute value of the voltage of the target conductor is maintained below the predetermined voltage. As described above, second protection device 13 protects camera 14 from application of an overvoltage whose absolute value exceeds a predetermined voltage. Camera 14 functions as a second electrical device.

[0028] For example, communication cable A3 is placed outdoors. If lightning occurs near communication cable A3, the absolute value of the voltage of the target conductor within communication cable A3 may increase. If the absolute value of the voltage of each of communication conductors 2a, 2b, 3a, and 3b is less than a predetermined voltage, first protection device 12 or second protection device 13 does not reduce the voltage of communication conductors 2a, 2b, 3a, and 3b, but maintains the voltage of communication conductors 2a, 2b, 3a, and 3b.

[0029] In the test system 1, the surge generator 15 applies a positive or negative surge voltage to the discharge conductor B2. FIG. 1 shows waveforms of the positive and negative surge voltages. For these waveforms, the vertical axis represents the voltage with the reference potential at ground potential. The horizontal axis represents time. In each of the positive and negative surge voltage waveforms, the absolute value of the voltage rises rapidly from 0 V and then gradually decreases. The absolute values ​​of the positive and negative surge voltages exceed a predetermined voltage. The surge voltages used are voltages whose absolute values ​​are within the range allowed by the first and second protection devices 12 and 13. For example, the surge voltages used are voltages whose maximum absolute value is 10 kV or less. Voltages whose maximum absolute value is 10 kV or more may also be used as long as they are within the allowed range.

[0030] The surge generator 15 applies a positive or negative surge voltage to the discharge conductor B2. This creates a state in which a surge voltage is applied to at least one of the communication conductors 2a, 2b, 3a, and 3b. When the surge generator 15 applies a positive surge voltage to the discharge conductor B2, current flows from the surge generator 15 to the discharger F of the second protector 13, the second diode Db of the second protector 13, the communication conductor 2a, the first diode Da of the first protector 12, the discharger F of the first protector 12, and the ground, as shown by the solid arrows in FIG. 2. FIG. 2 shows the current flowing through the communication conductor 2a. When the surge generator 15 applies a positive surge voltage to the discharge conductor B2, current flows through each of the communication conductors 2b, 3a, and 3b, similar to the current flowing through the communication conductor 2a.

[0031] When surge generator 15 applies a negative surge voltage to discharge conductor B2, as shown by the dashed arrow in Fig. 2, current flows from the ground through discharger F of first protector 12, second diode Db of first protector 12, communication conductor 2a, first diode Da of second protector 13, discharger F of second protector 13, and surge generator 15 in this order. Fig. 2 shows the current flowing through communication conductor 2a. When surge generator 15 applies a negative surge voltage to discharge conductor B2, current flows through each of communication conductors 2b, 3a, and 3b, similar to the current flowing through communication conductor 2a.

[0032] The tester performs a test to confirm whether second protection device 13 is operating normally. First, the tester connects power supply 11 to power source 16. This causes power supply 11 to supply power to camera 14 via communication lines 2 and 3. The tester operates information processing terminal 10 to instruct the information processing terminal 10 to perform various operations. After connecting power supply 11 to power source 16, the tester instructs information processing terminal 10 to receive a differential signal transmitted from camera 14 to power supply 11 via at least one of communication lines 2 and 3. The tester further instructs information processing terminal 10 to display an image of the image data included in the received differential signal on the display.

[0033] The tester operates surge generator 15 to instruct it to perform various operations. With the information processing terminal 10 displaying an image of the image data included in the differential signal received from camera 14, the tester instructs surge generator 15 to apply a positive or negative surge voltage to discharge conductor B2. Therefore, during the application period in which the positive or negative surge voltage is being applied, information processing terminal 10 receives the differential signal transmitted from camera 14 to power feeder 11 via at least one of communication lines 2 and 3.

[0034] The tester determines which of four criteria the operation of the camera 14 meets. The first criterion indicates that the operation is normal. In the test system 1, if the image displayed by the information processing terminal 10 is not distorted, the operation of the camera 14 meets the first criterion.

[0035] The second criterion indicates a temporary loss of functionality that does not require operator operation, or a temporary degradation of performance that does not require operator operation. In the test system 1, updating of the image displayed by the information processing terminal 10 is temporarily stopped. However, if the information processing terminal 10 resumes updating the image before the tester operates the information processing terminal 10 or the camera 14, the operation of the camera 14 meets the second criterion.

[0036] The third criterion indicates a temporary loss of a function that requires operator operation, or a temporary degradation of performance that requires operator operation. In the test system 1, the information processing terminal 10 stops updating the image displayed. However, if the tester operates the information processing terminal 10 or the camera 14, the information processing terminal 10 resumes updating the image. In this case, the operation of the camera 14 corresponds to the third criterion.

[0037] The fourth criterion indicates a loss of functionality that results in permanent damage to the equipment. In the test system 1, the information processing terminal 10 stops displaying images. Furthermore, even if the tester operates the information processing terminal 10 or the camera 14, the information processing terminal 10 does not resume displaying images. In this case, the operation of the camera 14 corresponds to the fourth criterion.

[0038] For example, if the operation of the camera 14 satisfies one of the first to third criteria, the tester determines that the second protection device 13 is operating normally. If the operation of the camera 14 satisfies one of the fourth criteria, the tester determines that the second protection device 13 is operating normally.

[0039] As described above, the tester can check whether the second protection device 13 is operating normally based on the image data contained in the differential signal received by the information processing terminal 10 from the camera 14 during the period in which the positive or negative surge voltage is applied.

[0040] (Embodiment 2) In the first embodiment, the test is performed by applying a positive or negative surge voltage to the discharge conductor B2. However, the test may also be performed by applying a positive or negative surge voltage to the discharge conductor B1. 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.

[0041] FIG. 3 is a block diagram showing the main configuration of the test system 1 in the second embodiment. Comparing the first and second embodiments, the connection location of the surge generator 15 is different. In the second embodiment, the first protection device 12 is connected to the surge generator 15 by a discharge conductor B1. The power supply 11 is connected midway through the discharge conductor B1. The surge generator 15 is grounded. The discharge conductor B2 connected to the second protection device 13 is grounded. The camera 14 is connected midway through the discharge conductor B2.

[0042] In the second embodiment, surge generator 15 applies a positive or negative surge voltage to discharge conductor B1. In the second embodiment, the current that flows when a positive surge voltage is applied to discharge conductor B1 is the same as the current that flows when a negative surge voltage is applied to discharge conductor B2 in the first embodiment. In the second embodiment, the current that flows when a negative surge voltage is applied to discharge conductor B1 is the same as the current that flows when a positive surge voltage is applied to discharge conductor B2 in the first embodiment.

[0043] In the second embodiment, a tester performs a test to confirm whether the first protection device 12 is operating normally. The test method of the second embodiment is the same as that of the first embodiment. Accordingly, the tester connects the power supply 11 to the power source 16. Next, the tester instructs the information processing terminal 10 to receive a differential signal transmitted from the camera 14 toward the power supply 11 via at least one of the communication lines 2 and 3. The tester further instructs the information processing terminal 10 to display an image of the image data included in the received differential signal on the display. While the information processing terminal 10 is displaying the image of the image data included in the differential signal received from the camera 14, the tester instructs the surge generator 15 to apply a positive or negative surge voltage to the discharge conductor B1. Accordingly, during the application period in which the positive or negative surge voltage is applied, the information processing terminal 10 receives the differential signal transmitted from the camera 14 toward the power supply 11 via at least one of the communication lines 2 and 3.

[0044] The tester determines which of the four criteria applies to the operation of the information processing terminal 10. The four criteria are as described in the first embodiment.

[0045] As described above, the tester can check whether the first protection device 12 is operating normally based on the image data contained in the differential signal received by the information processing terminal 10 from the camera 14 during the period in which a positive or negative surge voltage is applied.

[0046] (Embodiment 3) In the first embodiment, the electrical device connected to the second protection device 13 is the camera 14. However, the electrical device connected to the second protection device 13 is not limited to the camera 14. The following describes the differences between embodiment 3 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.

[0047] FIG. 4 is a block diagram showing the main configuration of a test system 1 according to a third embodiment. Comparing the first and third embodiments, the electrical devices connected to the first and second protection devices 12 and 13 are different. The test system 1 according to the third embodiment includes an amplifier 17 instead of the power supply 11 and a speaker 18 instead of the camera 14. The amplifier 17 and the speaker 18 are electrical devices. The information processing terminal 10 is connected to the amplifier 17 via a communication cable A1. The amplifier 17 is connected to the first protection device 12 via a communication cable A2. The amplifier 17 is connected to the middle of the discharge conductor B1. The second protection device 13 is connected to the speaker 18 via a communication cable A4. The speaker 18 is connected to the middle of the discharge conductor B2. The speaker 18 is installed outdoors, for example. The speaker 18 outputs, for example, sounds related to disaster prevention. The first protection device 12 and the second protection device 13 protect the amplifier 17 and the speaker 18 from the application of overvoltage. The amplifier 17 and the speaker 18 function as a first electric device and a second electric device, respectively.

[0048] In the third embodiment, the communication line 3 is not provided, and the information processing terminal 10 is connected to the speaker 18 via the communication line 2. The communication line 2 passes through the communication cable A1, the amplifier 17, the communication cable A2, the first protection device 12, the communication cable A3, the second protection device 13, and the communication cable A4. Therefore, the amplifier 17 is connected to the speaker 18 via the communication line 2. The information processing terminal 10 continuously transmits an audio signal to the speaker 18 via the communication line 2. The audio signal is, for example, an analog signal. The communication conductor 2b applies a voltage at a reference potential to the communication conductor 2a. As a result, the audio signal is transmitted via the communication line 2. The voltage waveform applied to the communication conductor 2a corresponds to the audio.

[0049] The number of speakers 18 included in the test system 1 is not limited to one and may be two or more. When the number of speakers 18 included in the test system 1 is two, the information processing terminal 10 is connected to the second speaker 18 via the communication line 3 described in the first embodiment. The communication line 3 passes through the communication cable A1, the amplifier 17, the communication cable A2, the first protection device 12, the communication cable A3, the second protection device 13, and the communication cable A4. Therefore, the amplifier 17 is connected to the second speaker 18 via the communication line 3. The communication conductor 3b applies a voltage that is a reference potential to the communication conductor 3a. As a result, an audio signal is transmitted via the communication line 3. The voltage waveform applied to the communication conductor 3a corresponds to audio.

[0050] When the number of communication lines is one, the first protection device 12 and the second protection device 13 each have two first diodes Da and two second diodes Db. Two first diodes Da are connected to the communication conductors 2a and 2b, respectively, and two second diodes Db are connected to the communication conductors 2a and 2b, respectively. When the number of communication lines is two, the first protection device 12 and the second protection device 13 are each configured similarly to the first embodiment. Note that the number of communication conductors included in each of the communication lines 2 and 3 is not limited to two and may be three or more.

[0051] The amplifier 17 amplifies the intensity of the audio signal input from the information processing terminal 10 via the communication line 2, and transmits the amplified audio signal to the speaker 18 via the communication line 2. When the number of communication lines is two, the amplifier 17 similarly amplifies the intensity of the audio signal input from the information processing terminal 10 via the communication line 3, and transmits the amplified audio signal to the second speaker 18 via the communication line 3. When the speaker 18 receives an audio signal from the information processing terminal 10, it outputs the audio of the received audio signal. The information processing terminal 10 has, for example, a microphone. The information processing terminal 10 transmits, for example, an audio signal of audio collected by the microphone to the speaker 18 via the amplifier 17.

[0052] The tester performs a test to confirm whether the second protection device 13 is operating normally. First, the tester instructs the information processing terminal 10 to continuously transmit an audio signal to the speaker 18. As described above, when the speaker 18 receives an audio signal, it outputs the sound of the audio signal.

[0053] While the information processing terminal 10 is continuously transmitting an audio signal to the speaker 18, the tester instructs the surge generator 15 to apply a positive or negative surge voltage to the discharge conductor B2. Therefore, the information processing terminal 10 continuously transmits an audio signal to the speaker 18 via at least one of the communication lines 2 and 3 during the application period in which the positive or negative surge voltage is being applied.

[0054] As in the first embodiment, the tester determines which of the four criteria applies to the operation of the speaker 18. In the test system 1, if the sound output from the speaker 18 is not interrupted, the operation of the speaker 18 applies to the first criterion.

[0055] In the test system 1, the output of sound from the speaker 18 is temporarily stopped. However, if the speaker 18 resumes output of sound before the tester operates the information processing terminal 10 or the speaker 18, the operation of the speaker 18 satisfies the second criterion.

[0056] In the test system 1, the output of sound from the speaker 18 stops. However, if the tester operates the information processing terminal 10 or the speaker 18, the speaker 18 resumes output of sound. In this case, the operation of the speaker 18 satisfies the third criterion.

[0057] In the test system 1, the speaker 18 stops outputting sound. Furthermore, even if the tester operates the information processing terminal 10 or the speaker 18, the speaker 18 does not resume outputting sound. In this case, the operation of the speaker 18 satisfies the fourth criterion.

[0058] As described above, the tester can check whether the second protection device 13 is operating normally based on the operation of the speaker 18 during the period in which a positive or negative surge voltage is applied.

[0059] (Fourth embodiment) In the third embodiment, the test is performed by applying a positive or negative surge voltage to the discharge conductor B2. However, the test may also be performed by applying a positive or negative surge voltage to the discharge conductor B1. The following describes the differences between embodiment 4 and embodiment 3. Except for the configuration described below, the other configurations are common to embodiment 3, and therefore the same reference numerals as in embodiment 1 are used for the components common to embodiment 3, and the description thereof will be omitted.

[0060] FIG. 5 is a block diagram showing the main configuration of the test system 1 in embodiment 4. Comparing embodiments 3 and 4, the connection location of the surge generator 15 is different. In embodiment 4, the first protection device 12 is connected to the surge generator 15 by a discharge conductor B1. The amplifier 17 is connected midway through the discharge conductor B1. The surge generator 15 is grounded. The discharge conductor B2 connected to the second protection device 13 is grounded. The speaker 18 is connected midway through the discharge conductor B2.

[0061] In embodiment 4, surge generator 15 applies a positive or negative surge voltage to discharge conductor B1. In embodiment 4, when a positive surge voltage is applied to discharge conductor B1, current flows in the same manner as in embodiment 2. When a negative surge voltage is applied to discharge conductor B1, current flows in the same manner as in embodiment 2.

[0062] In the fourth embodiment, the tester performs a test to confirm whether the first protection device 12 is operating normally. The test method of the fourth embodiment is the same as the test method of the third embodiment. Accordingly, the tester instructs the information processing terminal 10 to continuously transmit an audio signal to the speaker 18. When the speaker 18 receives an audio signal, it outputs the audio of the received audio signal. While the speaker 18 is outputting audio, the tester instructs the surge generator 15 to apply a positive or negative surge voltage to the discharge conductor B1. Accordingly, the information processing terminal 10 continuously transmits an audio signal to the speaker 18 via the communication line 2 or the communication line 3 during the application period in which the positive or negative surge voltage is being applied.

[0063] As in the third embodiment, the tester determines which of the four criteria applies to the operation of the information processing terminal 10. The four criteria are the same as those described in the first embodiment.

[0064] As described above, the tester can check whether the first protection device 12 is operating normally based on the operation of the speaker 18 during the period when a positive or negative surge voltage is applied.

[0065] In the first and second embodiments, there is no problem as long as the second electrical device connected to the second protection device 13 is a device that transmits a signal to the information processing terminal 10. Therefore, the second electrical device connected to the second protection device 13 is not limited to the camera 14. In the third and fourth embodiments, there is no problem as long as the second electrical device connected to the second protection device 13 is a device that receives a signal from the information processing terminal 10. Therefore, the second electrical device connected to the second protection device 13 is not limited to the speaker 18. In the third and fourth embodiments, power may be supplied to the second electrical device via the communication lines 2 and 3, as in the first embodiment.

[0066] In the first to fourth embodiments, the number of communication lines connected between the information processing terminal 10 and the second electric device is not limited to 2, and may be 1 or 3 or more. The number of first diodes Da and second diodes Db matches the number of communication conductors connected between the information processing terminal 10 and the second electric device.

[0067] In the first and second embodiments, the communication conductor included in the communication line also serves as a power supply conductor. However, a power supply conductor may be connected between the power supply device 11 and the second electric device separately from the communication conductor. The power supply device 11 supplies DC power to the second electric device via the power supply conductor. In this case, for example, current flows from the power supply device 11 to the second electric device via two power supply conductors, and returns from the second electric device to the power supply device 11 via two power supply conductors different from the two power supply conductors described above.

[0068] When a power supply conductor is connected between the power supply unit 11 and the second electrical device separately from the communication conductor, the first protection device 12 and the second protection device 13 each maintain the absolute value of the voltage of the power supply conductor at or below a predetermined voltage, similar to the absolute value of the voltage of the communication conductor. In this case, the number of first diodes Da and second diodes Db is equal to the total number of communication conductors and power supply conductors connected between the information processing terminal 10 and the second electrical device. The anode of each first diode Da is connected to the communication conductor or the power supply conductor. The cathode of each second diode Db is also connected to the communication conductor or the power supply conductor.

[0069] In the first and second embodiments, when a power source that supplies power to an electric device is located near a second electric device, the configuration of the test system 1 may be such that the power supply 11 is the first electric device as a communication interface without a power supply function, or may be such that the power supply 11 is omitted. In the configuration without the power supply 11, the information processing terminal 10 is connected to the first protection device 12 via a communication cable A1. The second electric device is supplied with power from a power source located near the second electric device. In the configuration without the power supply 11, the first protection device 12 protects the information processing terminal 10 from application of an overvoltage. In this case, the information processing terminal 10 functions not only as a device that receives signals but also as the first electric device.

[0070] In the third and fourth embodiments, if the information processing terminal 10 or the speaker 18 has a built-in amplifier, the configuration of the test system 1 may be such that the amplifier 17 is omitted. In this case, the information processing terminal 10 is connected to the first protection device 12 via the communication cable A1. In the configuration without the amplifier 17, the first protection device 12 protects the information processing terminal 10 from application of an overvoltage. In this case, the information processing terminal 10 functions not only as a device that transmits signals but also as a first electrical device.

[0071] In the first to fourth embodiments, each of the first protection device 12 and the second protection device 13 is not limited to a configuration including a first diode Da, a second diode Db, and a discharger F, as long as it is a device that causes a current to flow through the discharge conductors B1 and B2 when the absolute value of the voltage of the communication conductor or the power supply conductor exceeds a predetermined voltage.

[0072] The technical features (constituent elements) described in the first to fourth embodiments can be combined with each other, and by combining them, new technical features can be formed. The disclosed embodiments 1 to 4 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. [Explanation of symbols]

[0073] 1 Test system, 2, 3 Communication line, 2a, 2b, 3a, 3b Communication conductor (power supply conductor), 10 Information processing terminal, 11 Power supply (first electrical equipment), 12 First protection device, 13 Second protection device, 14 Camera (second electrical equipment), 15 Surge generator, 17 Amplifier (first electrical equipment), 18 Speaker (second electrical equipment), B1, B2 Discharge conductor, Da First diode, Db Second diode, F Discharger

Claims

1. a step of applying a surge voltage whose absolute value exceeds the predetermined voltage to a discharge conductor of one of a first protection device and a second protection device, the first protection device and the second protection device being arranged in the middle of a communication line connected between a first electric device and a second electric device, and protecting the first electric device and the second electric device from application of an overvoltage whose absolute value exceeds the predetermined voltage by passing a current through a discharge conductor different from the communication conductor when the absolute value of the voltage of the communication conductor included in the communication line becomes equal to or greater than a predetermined voltage; receiving a signal transmitted from the second electrical device via the communication line to the first electrical device during an application period in which the surge voltage is applied, or transmitting a signal to the second electrical device via the communication line during the application period; Test methods including:

2. supplying power to the second electrical device via a power supply conductor; The first protection device and the second protection device each pass a current through the discharge conductor when the absolute value of the voltage of the power supply conductor becomes equal to or greater than the predetermined voltage. The test method of claim 1.

3. a first electrical device; a second electrical device connected to the first electrical device by a communication line; a first protection device and a second protection device that are arranged midway along the communication line, and that, when the absolute value of a voltage of a communication conductor included in the communication line becomes equal to or greater than a predetermined voltage, protect the first electrical device and the second electrical device, respectively, from application of an overvoltage whose absolute value exceeds the predetermined voltage by causing a current to flow through a discharge conductor that is different from the communication conductor; a surge generator that applies a surge voltage having an absolute value exceeding the predetermined voltage to the discharge conductor of one of the first protection device and the second protection device; an information processing terminal that receives a signal transmitted from the second electrical device to the first electrical device via the communication line during an application period in which the surge generator applies the surge voltage, or that transmits a signal to the second electrical device via the communication line during the application period; A test system comprising:

4. Power is supplied to the second electrical device via a power supply conductor, The first protection device and the second protection device each pass a current through the discharge conductor when the absolute value of the voltage of the power supply conductor becomes equal to or greater than the predetermined voltage. The test system of claim 3 .

5. At least one of the first protection device and the second protection device is a first diode having an anode connected to the communication conductor; a second diode having a cathode connected to the communication conductor; a discharger connected to the cathode of the first diode, the anode of the second diode, and the discharge conductor, and configured to cause a current to flow through the discharge conductor when the absolute value of the voltage of the communication conductor becomes equal to or greater than the predetermined voltage; 5. The test system according to claim 3 or claim 4, comprising:

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