JP2007309731A - Clamp type ammeter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clamp type ammeter capable of simultaneously reducing electric power consumption in measuring work and improving convenience. <P>SOLUTION: The clamp type ammeter includes both a clamp sensor 2 for detecting a current flowing through a clamped electric wire 200 and outputting detection signals and a control part for computing a value of the current on the basis of detection signals output from the clamp sensor 2 and executing the processing of halting power supply that halts power supply for a display part 42, an operating part 44, etc. by controlling a power supply part when the state of the computed value of the current equal to a prescribed value or less has continued for a prescribed time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a clamp-type ammeter equipped with a clamp sensor that detects a current flowing in a clamped measurement object and outputs a detection signal.

As this type of clamp-type ammeter, a clamp-type leakage ammeter disclosed in Japanese Patent Application Laid-Open No. 2004-361248 is known. This clamp type leak current meter is provided with a clamp part that clamps a measured electric wire as a measurement object, and is configured to be able to detect a leakage current by clamping the measured electric wire at the clamp part. In this case, this type of clamp-type ammeter generally employs a configuration including a power switch for starting and stopping power supply. Therefore, by turning on / off the power switch, power supply can be started at the start of current measurement, and power supply can be stopped at the end of current measurement.
JP-A-2004-361248 (pages 7-13 and 17-18)

  However, the clamp-type ammeter has the following problems. That is, in this clamp type ammeter, the power supply is stopped when the power switch is turned off. For this reason, when the clamp-type ammeter is left in a state where the power supply is maintained, there is a problem that power is wasted as a result of the power supply being continued. In addition, when the power supply is stopped, the power switch must be operated, and the operation is complicated. Therefore, improvement of this point is desired in order to improve convenience during measurement work. In this case, for example, it may be possible to adopt a configuration in which power supply is automatically stopped when a certain time has elapsed since the last operation of the various operation switches including the power switch. In this configuration, even when the power switch is forgotten to be turned off, it is possible to reliably avoid a situation where power is wasted. However, when a certain time has elapsed since the last operation of the operation switch, the power supply is forcibly stopped regardless of whether or not current measurement is being performed. Therefore, there is still a problem that power is wasted because a certain time must be set in advance to avoid a situation where the power supply is suddenly stopped during the measurement operation.

  The present invention has been made in view of such problems, and a main object of the present invention is to provide a clamp-type ammeter that can simultaneously reduce power consumption and improve convenience during measurement work.

  In order to achieve the above object, a clamp type ammeter according to claim 1 is based on a clamp sensor that detects a current flowing through a clamped measurement object and outputs a detection signal, and the detection signal output by the clamp sensor. The power supply is stopped by controlling the power supply unit and stopping the power supply to a predetermined circuit when the state where the calculated current value is equal to or less than the predetermined value continues for a predetermined time. And a control unit that executes processing.

  A clamp-type ammeter according to claim 2 is the clamp-type ammeter according to claim 1, further comprising a first operation unit for setting the predetermined value.

  According to a third aspect of the present invention, there is provided a clamp type ammeter according to the first or second aspect, further comprising a second operation unit for setting the predetermined time.

  A clamp type ammeter according to claim 4 is the clamp type ammeter according to any one of claims 1 to 3, further comprising a detection unit that detects an open state of the clamp sensor, and the control unit includes When the open state of the clamp sensor is detected by the detection unit in a state where power supply to the predetermined circuit by the power supply unit is stopped, the predetermined circuit is controlled by controlling the power supply unit. The power supply to is started.

  According to the clamp-type ammeter according to claim 1, when the state where the calculated current value is equal to or less than a predetermined value (for example, zero ampere) continues for a predetermined time, the power supply to a predetermined circuit By stopping the supply, the power supply is automatically stopped when a predetermined time has elapsed without performing the measurement work, so that the operation of stopping the power supply can be made unnecessary. Convenience can be improved. Further, since the power supply is continued when the calculated current value exceeds a predetermined value, it is possible to reliably avoid a situation where the power supply is suddenly stopped during the measurement operation. For this reason, the predetermined time until the power supply is stopped can be set shorter than the configuration in which the power supply is forcibly stopped when a certain time has elapsed since the operation switch was last operated. As a result, it is possible to avoid a situation where power is continuously supplied and power is wasted even though current measurement is not performed. Therefore, according to this clamp-type ammeter, it is possible to simultaneously improve convenience and reduce power consumption during measurement work.

  Further, in the clamp type ammeter according to claim 2, when the state in which the calculated current value is equal to or less than a predetermined value set by the operation of the first operation unit continues for a predetermined time, the control unit Execute. Therefore, according to this clamp type ammeter, the magnitude | size of the predetermined value can be arbitrarily set by operating the 1st operation part.

  Further, in the clamp type ammeter according to claim 3, when the state where the calculated current value is equal to or less than the predetermined value continues for a predetermined time set by the operation of the second operation unit, the power supply stop process Execute. Therefore, according to this clamp type ammeter, the time length of the predetermined time can be arbitrarily set by operating the second operation unit.

  According to the clamp type ammeter of claim 4, when the control unit detects the open state of the clamp sensor in the state where the power supply is stopped, the control unit applies the predetermined amount to the predetermined circuit. By starting power supply, power supply can be started simply by opening the clamp sensor. This eliminates the need for switch operation to start power supply. Can be improved with certainty.

  Hereinafter, the best mode of a clamp type ammeter according to the present invention will be described with reference to the accompanying drawings.

  First, the configuration of the clamp-type ammeter 1 will be described with reference to the drawings. A clamp-type ammeter 1 shown in FIG. 1 includes a clamp sensor 2 and a main body 4, and is configured to be able to measure a current I flowing in a clamped electric wire 200 (measurement object in the present invention) without contact, for example. Has been. As shown in FIGS. 1 and 3, the clamp sensor 2 includes a first sensor 3 a and a second sensor 3 b (hereinafter also referred to as “sensor 3” when they are not distinguished from each other). It is comprised so that mutual contact is possible.

  As shown in FIGS. 1 and 3, the first sensor 3 a includes a case 11 a having a substantially arc shape in plan view, and a current detection coil 12 housed in the case 11 a. 4 is rotatably attached and is urged in the direction of arrow A shown in FIG. 3 by a spring not shown. The case 11a constitutes a coil housing part 21 having a substantially arc shape in plan view for housing the coil 12, and a lever 22 for rotating the first sensor 3a when the clamp-type ammeter 1 is used.

  As shown in FIGS. 1 and 3, the second sensor 3b includes a case 11b having a substantially arc shape in plan view, and a coil 12 for current detection accommodated in the case 11b. 4 is rotatably attached and is urged in the direction of arrow B shown in FIG. The case 11b constitutes the coil housing portion 21 and the lever 22 in the same manner as the case 11a described above.

  In this case, as shown in FIG. 1, the first sensor 3 a and the second sensor 3 b form an annular body in which the tip portions 31 approach each other in a state where the first sensor 3 a and the second sensor 3 b are not urged by the lever 22. In this state, the coil 12 detects a current flowing in the electric wire 200 clamped by the clamp sensor 2 and outputs a detection signal Sd.

  As shown in FIG. 2, the main unit 4 includes an A / D conversion unit 41, a display unit 42, a storage unit 43, an operation unit 44, a detection unit 45, a power supply unit 46, a timer 47, a control unit 48, and each of these. A case 49 (see FIG. 1) in which components are accommodated or disposed is provided. The A / D converter 41 performs analog-digital conversion on the detection signal Sd output from the coil 12 of the clamp sensor 2 and outputs current data Di. The display unit 42 is composed of a liquid crystal panel, for example, and is disposed on the front panel of the case 49. The display unit 42 displays various measurement values and the like according to the control of the control unit 48.

  The storage unit 43 stores reference current data Ds indicating a reference current value Is corresponding to a predetermined value in the present invention and standby time data Dt indicating a standby time tw corresponding to a predetermined time in the present invention. Here, the reference current value Is is a current value that serves as a determination reference when determining that the current I is not flowing, and is set to an arbitrary value. The standby time tw is a time to wait between when it is determined that the current I is not flowing and until the power supply is stopped, and is set to an arbitrary length of time. The operation unit 44 corresponds to the first operation unit and the second operation unit in the present invention, and includes a numerical value setting switch for setting the reference current value Is and the standby time tw to arbitrary values. As shown in FIG. The operation unit 44 outputs an operation signal corresponding to the switch operation. The detection unit 45 is composed of, for example, a mechanical switch, and as shown in FIG. 3, when the switch unit is pushed when the lever 22 is pushed, the rotation of the first sensor 3 a, that is, the opening of the clamp sensor 2 is performed. The state is detected and a detection signal Ss is output.

  The power supply unit 46 includes a battery, and supplies power to each component of the clamp-type ammeter 1 according to the control of the control unit 48. Specifically, the power supply unit 46 supplies power to the circuits (the detection unit 45 and the control unit 48) that are at least necessary to detect the open state of the clamp sensor 2 when the power supply is stopped. Then, the power supply to the A / D conversion unit 41, the display unit 42, the operation unit 44, and the other components (predetermined circuit in the present invention) of the timer 47 is stopped. On the other hand, when supplying power to supply power, power is supplied to all circuits of the clamp-type ammeter 1 including the A / D conversion unit 41, the display unit 42, the operation unit 44, and the timer 47. Supply. The timer 47 counts the standby time tw according to the control of the control unit 48 and outputs a timer signal to the control unit 48 when the standby time tw elapses.

  The control unit 48 calculates a current value (current value in the present invention) Im based on the current data Di output from the A / D conversion unit 41 and causes the display unit 42 to display the calculated current value Im. Further, the control unit 48 controls each part of the main body unit 4 according to the operation signal output from the operation unit 44 and the detection signal Ss output from the detection unit 45. In this case, when the detection signal Ss is output from the detection unit 45, the control unit 48 executes the power supply control processing 60 shown in FIG. Further, when the reference current value Is and the standby time tw are set by the switch operation of the operation unit 44, the control unit 48 stores the reference current data Ds and the standby time data Dt corresponding to each set value in the storage unit 43. Remember me.

  Next, a method for measuring current using the clamp type ammeter 1 will be described with reference to the drawings.

  For example, when measuring the current I flowing through the electric wire 200 shown in FIG. 1, as shown in FIG. 3, the levers 22 and 22 of the first sensor 3a and the second sensor 3b are connected to the main body 4 side (same as the same). By pushing in the direction of the arrows C and D shown in the figure, the two sensors 3 are rotated in the directions of the arrows E and F shown in the figure, and the tip portions 31 and 31 of the sensors 3 are separated from each other. At this time, the detection unit 45 detects the open state of the clamp sensor 2 by the rotation of the lever 22 and outputs a detection signal Ss to the control unit 48. In response to this, the control unit 48 executes the power supply control process 60 shown in FIG. In this power supply control process 60, the control unit 48 first controls the power supply unit 46, and all circuits (A / D conversion unit 41, display unit) other than the control unit 48 and the detection unit 45 in the clamp type ammeter 1. Power supply to the unit 42, the operation unit 44, and the timer 47) is started (step 61). In this case, in the clamp type ammeter 1, unlike the conventional configuration in which power supply is started when the power switch is operated, power supply is started only by operating the lever 22 to open the clamp sensor 2. Is done.

  Subsequently, as shown in FIG. 1, the pushing of the levers 22 and 22 is released in a state where the electric wire 200 is surrounded by both sensors 3. At this time, both sensors 3 are rotated by the urging force of a spring not shown in the figure, and as shown in the figure, the tip portions 31 and 31 are connected to each other to form an annular body. Thereby, the clamp sensor 2 clamps the electric wire 200.

  At this time, the numerical value setting switch of the operation unit 44 is operated to set the reference current value Is to “0 amperes”, for example, and the standby time tw is set according to the configuration of the power supply unit 46 (for example, battery capacity). For example, “15 minutes” is set. In response to this, the control unit 48 generates the reference current data Ds corresponding to the set reference current value Is and the standby time data Dt corresponding to the set standby time tw and stores them in the storage unit 43.

  On the other hand, the coils 12 of both sensors 3 detect the current I flowing through the electric wire 200 and output a detection signal Sd. Next, the A / D conversion unit 41 performs analog-digital conversion on the detection signal Sd and outputs current data Di to the control unit 48. At this time, the control unit 48 calculates the current value Im based on the current data Di output by the A / D conversion unit 41 (step 62) and causes the display unit 42 to display the calculated current value Im. Subsequently, the control unit 48 reads the reference current data Ds from the storage unit 43 and determines whether or not the calculated current value Im is equal to or less than the reference current value Is indicated by the reference current data Ds (in this case, “0 ampere”). (Step 63). At this time, for example, when the current I is flowing through the electric wire 200, the current value Im exceeds the reference current value Is. Therefore, the control unit 48 determines that the current value Im is not less than or equal to the reference current value Is. The calculation process of the current value Im and the display process of the calculated current value Im are repeatedly executed.

  Next, for example, when the current I no longer flows through the electric wire 200, the current value Im and the reference current value Is become the same value (that is, zero amperes), so the control unit 48 determines that the current value Im is the reference value in the discrimination process of step 63. It is determined that the current value is less than or equal to Is. At this time, the control unit 48 controls the timer 47 to start counting the time t when the current value Im is equal to or less than the reference current value Is (step 64). Subsequently, the control unit 48 reads the standby time data Dt from the storage unit 43 and determines whether or not the time t at which the counting was started in step 64 has reached the standby time tw indicated by the standby time data Dt ( Step 65). At this time, when the standby time tw has not been reached, the control unit 48 calculates the current value Im in the same manner as the calculation process in step 62 (step 66) and displays the calculated current value Im. Subsequently, the control unit 48 determines whether or not the current value Im calculated in Step 66 is equal to or less than the reference current value Is (Step 67). At this time, since the current value Im and the reference current value Is are the same value (that is, zero amperes) when the current I is not flowing through the electric wire 200, the control unit 48 determines that the current value Im is determined in step 67. It is determined that the current value is equal to or less than the reference current value Is, and the processes of steps 65 and 66 are repeatedly executed.

  On the other hand, when the standby time tw is reached, the timer 47 outputs a timer signal to the control unit 48. In response to this, the control unit 48 determines that the time t has reached the standby time tw in the determination process of step 65. In this case, the control unit 48 controls the power supply unit 46 to perform power supply stop processing for stopping the power supply to the A / D conversion unit 41, the display unit 42, the operation unit 44, and the timer 47 as described above. This is executed (step 68), and the power supply control process 60 is terminated. Therefore, in this clamp type ammeter 1, since the power supply is automatically stopped when the control unit 48 reaches the standby time tw, an operation for stopping the power supply is unnecessary.

  On the other hand, when the current I starts to flow again during the execution of the processes of steps 65 to 67, the control unit 48 determines that the current value Im is not less than or equal to the reference current value Is in the determination process of step 67, and the time t Is reset (step 69), and the processing after step 62 is executed. In this case, when the current I is flowing, the control unit 48 performs the calculation process of the current value Im and the display process of the current value Im without executing the power supply stop process of step 68. Therefore, the situation where the power supply is suddenly stopped during the measurement operation of the current I is reliably avoided.

  Thus, according to this clamp type ammeter 1, when the state where the current value Im is equal to or lower than the reference current value Is continues for the standby time tw, the control unit 48 determines a predetermined circuit (A By stopping the power supply to the / D conversion unit 41, the display unit 42, the operation unit 44, and the timer 47), the power supply is automatically stopped when the waiting time tw elapses without performing the measurement work. Therefore, the operation for stopping the power supply can be made unnecessary, and as a result, convenience during measurement work can be improved. Further, since the control unit 48 continues the power supply when the current value Im exceeds the reference current value Is, it is possible to reliably avoid a situation where the power supply is suddenly stopped during the measurement operation. For this reason, the length of the standby time tw can be set shorter as compared with the configuration in which the power supply is forcibly stopped when a certain time has elapsed since the last operation of the operation switch. Although the measurement is not performed, it is possible to avoid a situation where power is continuously supplied and power is wasted. Therefore, according to the clamp-type ammeter 1, it is possible to simultaneously improve convenience and reduce power consumption during measurement work.

  Further, in this clamp type ammeter 1, the control unit 48 stops the power supply when the state where the current value Im is equal to or lower than the reference current value Is set by the operation of the operation unit 44 continues for the standby time tw. Execute the process. Therefore, according to this clamp type ammeter 1, by operating the operation unit 44, the magnitude of the reference current value Is can be arbitrarily set.

  In the clamp type ammeter 1, the control unit 48 stops supplying power when the state where the current value Im is equal to or less than the reference current value Is continues for the standby time tw set by the operation of the operation unit 44. Execute the process. Therefore, according to this clamp type ammeter 1, the time length of the standby time tw can be arbitrarily set by operating the operation unit 44.

  Further, according to the clamp type ammeter 1, when the control unit 48 detects the open state of the clamp sensor 2 by the detection unit 45 in a state where the power supply is stopped, a predetermined circuit (A Since the power supply to the / D conversion unit 41, the display unit 42, the operation unit 44, and the timer 47) is started, the power supply can be started simply by opening the clamp sensor 2. As a result, it is possible to improve the convenience during measurement work.

  In addition, this invention is not limited to said structure. For example, although the example in which the reference current value Is is set to “0 ampere” has been described above, the present invention is not limited to this. For example, the reference current value Is can be set to an arbitrary value according to the current value to be measured. Further, although the example in which the standby time tw is set to “15 minutes” has been described above, the present invention is not limited to this, and the standby time tw can be set to an arbitrary time length. Moreover, although the structure provided with the mechanical switch as the detection part 45 was demonstrated, the structure provided with an optical switch as the detection part 45 is also employable.

It is a front view of clamp type ammeter 1 in the state where electric wire 200 was clamped. 1 is a block diagram of a clamp-type ammeter 1. FIG. It is a front view of the clamp type ammeter 1 in a state where the first sensor 3a and the second sensor 3b are rotated (when the clamp sensor 2 is opened). 5 is a flowchart of a power supply control process 60.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Clamp type ammeter 2 Clamp sensor 22 Lever 41 A / D conversion part 44 Operation part 45 Detection part 46 Power supply part 47 Timer 48 Control part 200 Electric wire I Current Im Current value Is Reference current value tw Standby time

Claims (4)

  A clamp sensor that detects a current flowing in the clamped measurement object and outputs a detection signal; calculates a current value based on the detection signal output by the clamp sensor; and the calculated current value is predetermined. A clamp-type ammeter comprising: a control unit that executes a power supply stop process for controlling the power supply unit to stop the power supply to a predetermined circuit when a state that is equal to or less than the value continues for a predetermined time.   The clamp type ammeter according to claim 1, further comprising a first operation unit for setting the predetermined value.   The clamp type ammeter according to claim 1 or 2, further comprising a second operation unit for setting the predetermined time. A detection unit for detecting an open state of the clamp sensor;
The control unit controls the power supply unit when the detection unit detects an open state of the clamp sensor in a state where power supply to the predetermined circuit by the power supply unit is stopped. The clamp type ammeter according to any one of claims 1 to 3, wherein power supply to the predetermined circuit is started.

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