Detection signal input converter and detection signal input system

Abstract

To provide a detection signal input converter that can automatically take noise countermeasures against shielded cables connected to a detector in environments where strong radiation noise is generated.SOLUTION: A detection signal input converter for accepting input of a detection signal detected by a detector through a shielded cable protected from noise by a shield includes: a noise detection unit that detects noise superimposed on a signal line from the detection signal; and a shield connection destination switching unit that switches a connection destination of the shield of the shielded cable when the noise detection unit detects noise.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present application relates to a detection signal input converter and a detection signal input system that input a detection signal detected by a detector via a shielded cable. [Background technology]

[0002] In a detector for monitoring the operating status of the turbine and generator of a turbine power generation facility, it is necessary to protect the detection signal from radiation noise generated by the power generation facility. For this reason, a shielded cable is used to connect the detection signal detected by the detector to a detection signal input converter that inputs the detection signal to a monitoring device. The shielded cable is used to protect the detection signal from noise by covering the signal line with a shield.

[0003] It is standard practice to connect the shield of the shielded cable from the detector to the common terminal of the detection signal input converter. In a detector for a device that monitors the operating status of the turbine and generator of a turbine power generation facility, if there is no strong radiation noise on the shielded cable, the input of the detection signal input converter will be normal when connected to the common terminal. However, when the shield of the shielded cable is induced by strong radiation noise from surrounding power facilities, the shield of the shielded cable acts as an antenna, and the radiation noise from the shield is mixed into the signal line, causing the input of the detection signal input converter to suddenly change. In addition, the radiation noise from the shield is mixed in through the common terminal, causing the output from the detection signal input converter to suddenly become unstable. For example, the detector circuit for monitoring the operating state of the turbine and generator of a conventional turbine power generating facility shown in Patent Document 1 is provided with a relay circuit that disconnects the shield from the common terminal to create a floating state. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2005-249673 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the circuit of Patent Document 1 does not have a noise detection means for detecting noise, and cannot automatically take measures when radiation noise occurs. In addition, since the state of radiation noise generation changes over time, there is a problem in that it is not possible to take measures according to the occurrence state of noise superposition.

[0006] The present application discloses technology for solving such problems, and aims to provide a detection signal input converter that can automatically perform noise countermeasures by using a shielded cable connected to a detector in an environment where strong radiation noise is generated. [Means for solving the problem]

[0007] The detection signal input converter of the present application is a detection signal input converter that inputs a detection signal detected by a detector via a shielded cable that protects the detection signal from noise by a shield, and is equipped with a noise detection unit that detects noise superimposed on a signal line from the detection signal, and a shield connection destination switching unit that switches the connection destination of the shield of the shielded cable when the noise detection unit detects noise. Effect of the Invention

[0008] According to the present application, there is provided a noise detection unit that detects noise superimposed on a signal line from a detection signal, and a shield connection destination switching unit that switches the connection destination of the shield of the shielded cable by the noise detection unit detecting noise. Therefore, when the noise detection unit detects noise superimposed on the signal line, the connection destination of the shield can be automatically switched, thereby reducing the effects of radiated noise. [Brief description of the drawings]

[0009] [Figure 1] 1 is a configuration diagram showing an overall configuration including a detection signal input converter, a detector, and a shielded cable according to a first embodiment. [Figure 2A] 4 is a characteristic diagram showing a detection signal in normal operation of the detection signal input converter according to the first embodiment. FIG. [Figure 2B] 4 is a characteristic diagram showing the appearance and disappearance of a detection signal having a large rate of change in detection value when noise is generated in the detection signal input converter according to the first embodiment. FIG. [Figure 2C] 4 is a characteristic diagram showing the occurrence and disappearance of a detection signal whose detection value is outside a range when noise occurs in the detection signal input converter according to the first embodiment. FIG. [Diagram 3] 5 is a flowchart showing an operation accompanying noise detection of the detection signal input converter according to the first embodiment. [Figure 4] 4 is a schematic diagram showing a control unit that controls a noise detection unit of the detection signal input converter according to the first embodiment. FIG. [Diagram 5] FIG. 11 is a configuration diagram showing an overall configuration including a detection signal input converter, a detector, and a shielded cable according to a second embodiment. [Figure 6] FIG. 11 is a configuration diagram showing an overall configuration including a detection signal input converter, a detector, and a shielded cable according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Embodiment 1 Fig. 1 is a diagram showing an overall configuration including a detection signal input converter, a detector, and a shielded cable according to a first embodiment of the present invention. In Fig. 1, the detector 1 is provided on the equipment side for a monitoring device (not shown) that monitors the operating conditions of the turbine and generator of the turbine power generation facility. The detection signal input converter 3 is provided on the monitoring device side, and converts the detection signal input from the detector 1 via the shielded cable 2 into a digital signal or the like and outputs it to the monitoring device.

[0011] The shielded cable 2 has a signal line 21 carrying a detection signal that becomes a voltage or current signal of the detector 1, and a shield 22 that covers the signal line 21 to protect the detection signal from noise. The signal line 21 is connected to a signal input unit 31 of the detection signal input converter 3 by a signal input terminal 311. The shield 22 of the shielded cable 2 is connected at its end as a ground line 221 to a common terminal 312 of the signal input unit 31 via a relay contact 331 of a shield connection destination switching unit 33 of the detection signal input converter 3. The common terminal 312 is connected to the frame ground of the detection signal input converter 3.

[0012] In addition, the detection signal input converter 3 has a signal input unit 31 that converts the detection signal input from the signal input terminal 311 and outputs it to the monitoring device, a noise detection unit 32 that detects the presence or absence of noise based on data sampled from the detection signal, and a shield connection destination switching unit 33 that switches the connection destination of the shield 22 of the shielded cable 2 when the noise detection unit 32 detects noise due to radiated noise 4.

[0013] 2A is a characteristic diagram showing changes in the detection signal of signal line 21 under normal conditions with little noise. Under normal conditions, no noise detection signal is output from noise detection unit 32, relay contact 331 of shield connection destination switching unit 33 is closed, and shield 22 of shielded cable 2 is connected to common terminal 312 of signal input unit 31. 2B and 2C are characteristic diagrams showing the change in the detection signal of the signal line 21 when noise occurs. FIG. 2B shows an example in which the rate of change of the detection signal suddenly increases due to the superposition of noise, and it is determined that there is noise when the rate of change of the detection signal under normal conditions is greater than a preset rate of change. In the generation zone Z1 shown by the dashed line in the figure, the data of the detection signal changes significantly up and down. In addition, in the end zone Z2, the change returns to normal. Specifically, it can be determined that noise has been detected when the absolute value of the difference Sd between the sampling data value of the detection signal and the previous sampling data value exceeds a preset difference value Ls. In addition, it can be determined that there is no noise if the absolute value of the difference Sd is within the preset difference value Ls. The sampling period is set to a time interval that allows the change due to noise to be detected.

[0014] FIG. 2C shows an example in which the data value of the detection signal suddenly increases or decreases due to the superposition of noise, and it is determined that noise is present when the amount of change in the detection signal data under normal conditions increases or decreases beyond a preset threshold. In the occurrence zone Z3 shown by the dashed line in the figure, the detection signal data changes significantly up and down and exceeds the preset value range. In the end zone Z4, it returns to the normal value range. Specifically, it can be determined that noise has been detected when the value of the detection signal detection data falls outside the preset maximum value Lmax and minimum value Lmin range. When noise occurs, the noise detection unit 32 outputs a noise detection signal, the relay contact 331 of the shield connection destination switching unit 33 opens, and the shield 22 of the shielded cable 2 is disconnected from the common terminal 312 of the signal input unit 31 and enters a floating state.

[0015] 3 is a flow chart showing the operation of the detection signal input converter 3 in detecting noise as described above. In FIG. 3, first, in step S1, the noise detection unit 32 acquires the sampling value Si of the detection signal input from the signal input terminal 311 to the signal input unit 31 at that time. In step S2, the noise detection unit 32 calculates the difference Sd from the previous sampling value Si-1. In step S3, the absolute value of the difference Sd is compared with a preset difference value Ls, and if it exceeds the difference value Ls, it is determined that there is noise and the process proceeds to step S7. Otherwise, in step S4, it is compared whether the sampling value Si is within a range between a preset maximum value Lmax and a minimum value Lmin, and if it is outside the range, it is determined that there is noise and the process proceeds to step S7. Otherwise, in step S5, it is determined that there is no noise and the process proceeds to step S6, where the relay contact 331 of the shield connection destination switching unit 33 is closed and the shield 22 of the shielded cable 2 is connected to the common terminal 312 of the signal input unit 31.

[0016] If it is determined in step S7 that there is noise, in step S8 the noise detection unit 32 outputs a noise detection signal to open the relay contact 331 of the shield connection destination switching unit 33, and the shield 22 of the shielded cable 2 is disconnected from the common terminal 312 of the signal input unit 31 and becomes in a floating state. Then, in step S9, the floating state is maintained for the duration of the continuation timer T. The continuation timer T prevents the change state of the detection signal with the noise superimposed thereon from settling down and immediately switching to a noise-free state after the noise is detected. The value of the continuation timer T may be changed depending on the noise state, or may be a value previously set according to the installation environment of the detector 1. After the time is up, in step S6 the shield 22 is returned to the common terminal 312 of the signal input unit 31. After step S6, the process returns to step S1 and the series of operations is repeated.

[0017] The above-mentioned operation is controlled by a control unit provided inside the noise detection unit 32. FIG. 4 is a schematic diagram showing the configuration of the control unit of the noise detection unit 32, which is composed of a processor 321 and a storage device 322. Although not shown, the storage device 322 includes a volatile storage device such as a random access memory and a non-volatile auxiliary storage device such as a flash memory. Also, instead of the flash memory, a hard disk auxiliary storage device may be included. The processor 321 executes a program input from the storage device 322, and performs part or all of the operations of the flowchart described in FIG. 3. In this case, the program is input from the auxiliary storage device to the processor 321 via the volatile storage device. Also, the processor 321 may output data such as input / output signals, intermediate values ​​of the calculation, and the calculation results to the volatile storage device of the storage device 322, or may store data in the auxiliary storage device via the volatile storage device. Also, in addition to the processor 321 and the storage device 322, a logic circuit and an analog circuit may be used in combination. Also, the noise detection unit 32 performs part or all of the operations described in the second and third embodiments described later.

[0018] As described above, when the noise detection unit 32 detects noise superimposed on the signal line 21 from the detection signal, the detection signal input converter 3 automatically switches the connection destination of the shield 22 of the shielded cable 2 from the common terminal 312 to a floating state by the shield connection destination switching unit 33, thereby reducing the influence of the radiation noise 4 on the signal line 21 of the shielded cable 2. This allows the detection signal input converter 3 to reduce the level of noise due to the radiation noise 4 superimposed on the detection signal from the signal input terminal 311 of the detection signal input converter 3. In addition, since the noise mixed in from the common terminal 312 of the detection signal input converter 3 is blocked, the detection signal input converter 3 can prevent the output from becoming unstable due to the mixing in of noise from the common terminal 312. Furthermore, during normal times when there is no noise or the noise level is low, the connection destination of the shield 22 of the shielded cable 2 is connected to the common terminal 312 by the shield connection destination switching unit 33, so that a stable detection signal can be obtained. Furthermore, since the noise detection section 32 is configured to detect the occurrence of noise from the detection signal itself, there is no need to install a separate device for noise detection.

[0019] Embodiment 2 Fig. 5 is a configuration diagram showing an overall configuration including a detection signal input converter 3 according to embodiment 2, a detector 1, and a shielded cable 2. Differences from embodiment 1 will be described with reference to Fig. 5. Note that parts corresponding to the components of embodiment 1 are indicated by the same reference numerals, and detailed description will be omitted. 5, shield connection destination switching unit 33 of detection signal input converter 3 is provided with relay contact 331 connected to common terminal 312 and relay contact 332 connected to earth 5. In embodiment 2, when noise occurs, noise detection unit 32 outputs a noise detection signal, and relay contact 331 of shield connection destination switching unit 33 opens and relay contact 332 closes, so that shield 22 of shielded cable 2 is disconnected from common terminal 312 of signal input unit 31 and connected to earth 5. In this way, the influence of noise can be reduced by switching the connection of shield 22 to earth 5 when noise occurs. If a sufficient noise reduction effect cannot be obtained in the first embodiment, in which shield 22 is switched to a floating state when noise occurs, a more effective noise reduction effect may be obtained in the second embodiment, in which shield 22 is switched to earth 5.

[0020] Embodiment 3 Fig. 6 is a configuration diagram showing an overall configuration including a detection signal input converter 3 according to embodiment 3, a detector 1, and a shielded cable 2. Differences from embodiments 1 and 2 will be described with reference to Fig. 6. Note that parts corresponding to the components of embodiments 1 and 2 are indicated by the same reference numerals, and detailed descriptions will be omitted. In Fig. 6, the shield 22 of the shielded cable 2 also has a ground wire 222 at the end on the detector 1 side, and is connected to the earth 5 via a relay contact 61 of a shield connection destination switch 6 provided on the detector 1 side. The relay contact 61 is normally open, so that the shield 22 of the shielded cable 2 is connected to the common terminal 312 only on the detection signal input converter 3 side. When noise occurs, a noise detection signal is output from the noise detection unit 32 to the shield connection destination switch 6 provided on the detector 1 side, closing the relay contact 61, and the shield 22 of the shielded cable 2 is connected to the earth 5. At the same time, the noise detection signal output from the noise detection unit 32 opens the relay contact 331 and closes the relay contact 332 of the shield connection destination switch 33 of the detection signal input converter 3, so that the shield 22 of the shielded cable 2 is disconnected from the common terminal 312 of the signal input unit 31 and connected to the earth 5. In this way, when noise occurs, the shield 22 of the shielded cable 2 is connected to the earth 5 at both ends of the cable.

[0021] In the third embodiment, when noise occurs, multi-point grounding can be performed by connecting the shield 22 of the shielded cable 2 to the earth 5 at both ends of the cable, thereby reducing the effects of noise. If a sufficient noise reduction effect cannot be obtained in the first embodiment in which the shield 22 is switched to a floating state when noise occurs, or in the second embodiment in which the shield 22 is switched to the earth 5, a more effective noise reduction effect may be obtained by using the configuration of the third embodiment in which the shield 22 is grounded to the earth 5 at multiple points.

[0022] In the first to third embodiments, the signal input unit 31, the noise detection unit 32 and the shield connection destination switching unit 33 have been described as parts of the components of the detection signal input converter 3, but each of them may be an independent device, and the same effect can be obtained even if they are configured as a detection signal input system including each device.

[0023] Although various exemplary embodiments and examples are described in this application, various features, aspects, and functions described in one or more embodiments are not limited to the application of a specific embodiment, but can be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are expected within the scope of the technology disclosed in this specification. For example, the following are included: when at least one component is modified, added, or omitted, and further, when at least one component is extracted and combined with a component of another embodiment. [Explanation of symbols]

[0024] 1 detector, 2 shielded cable, 21 signal line, 22 shield, 221, 222 ground line, 3 detection signal input converter, 31 signal input section, 311 signal input terminal, 312 common terminal, 32 noise detection section, 321 processor, 322 storage device, 33 shield connection destination switching section, 331, 332 relay contact, 4 radiation noise, 5 earth, 6 shield connection destination switch, 61 relay contact.

Claims

1. A detection signal input converter that inputs a detection signal detected by a detector via a shielded cable that protects the detection signal from noise by a shield, a noise detection unit that detects noise superimposed on a signal line from the detection signal; a shield connection destination switching unit that switches a connection destination of the shield of the shielded cable when the noise detection unit detects noise; A detection signal input converter comprising:

2. 2. The detection signal input converter according to claim 1, wherein the shield connection switching unit disconnects the connection destination of the shield of the shielded cable from the common terminal and maintains it in a floating state during a period when the noise detection unit is detecting noise.

3. 2. The detection signal input converter according to claim 1, wherein the shield connection switching section switches the connection destination of the shield of the shielded cable from a common terminal to earth during a period in which the noise detection section detects noise.

4. 2. The detection signal input converter according to claim 1, wherein the noise detection unit determines that noise has been detected when an absolute value of a difference between a sampling data value of the detection signal and a previous sampling data value exceeds a preset difference value.

5. 5. The detection signal input converter according to claim 1, wherein the noise detection unit determines that noise has been detected when a value of the detection data of the detection signal falls outside a preset range.

6. a detection signal input converter that inputs a detection signal detected by the detector via a shielded cable that protects the detection signal from noise by a shield; a noise detector that detects noise superimposed on a signal line from detection data of the detection signal; a shield connection switch that switches a connection destination of the shield of the shielded cable when the noise detector detects noise; A detection signal input system comprising:

7. the shield of the shielded cable is connected to both the detector and the detection signal input converter; 7. The detection signal input system according to claim 6, wherein a shield connection switch for switching the connection destination of the shield is provided on the side of the detector and on the side of the detection signal input converter.

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