JP2009068883A - Clamp tester - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a clamp tester capable of recognizing a heavy current instantly by another means, even if it is not recognized by a display means. <P>SOLUTION: This clamp tester 30 for measuring a leakage current of a wire, by clamping the wire is equipped with a measuring means 46 for measuring the leakage current; a vibrating motor 48; and a control means 50 for comparing a leakage current value, measured by the measuring means 46 with a threshold, set beforehand and controlling, so as to drive the vibrating motor 46, when the measured leakage current value exceeds the threshold. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a clamp tester that can clamp a wire and measure the leakage current of the wire.

2. Description of the Related Art Conventionally, a clamp tester that can measure a leakage current of an electric wire while keeping the state of a live wire without connecting or disconnecting the electric wire is known (see, for example, Patent Document 1 and Patent Document 2).
The clamp tester is measured by a magnetic field detection unit that detects a magnetic field generated around the electric wire, a current value measurement unit that measures the current value of leakage current based on the strength of the magnetic field detected by the magnetic field detection unit, and a current value measurement unit. Display means for displaying the current value of the leaked current.

In addition, the clamp tester includes a main body portion to be gripped by hand and a clamp portion formed in a ring shape at the tip of the main body portion. The clamp part is provided so that a ring-shaped part is opened and opened and closed, and a lever for opening and closing the clamp part is provided on the main body part.
Further, display means for displaying the measured current value is provided on the surface of the main body.

JP-A-6-235735 JP 2000-131343 A

  In the conventional clamp tester as described above, the measured result is only displayed on the display means. If the measurement work is performed in a relatively dark place or a narrow place, it is difficult to confirm the measurement result. There was a problem that it was difficult to perform a proper measurement work.

  In particular, when measuring the leakage current, there is a risk that the risk is high when the current value is large. In the case of a large current value, the current value is not confirmed visually but by another method. It is thought that it is necessary to make an operator instantly recognize that the value is large.

  Accordingly, the present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a clamp tester that can instantly recognize a large current by other means without being recognized by display means. There is to do.

According to the clamp tester according to the present invention, in the clamp tester for measuring the leakage current of the electric wire by clamping the electric wire, the leakage current value measured by the measurement means for measuring the leakage current, the vibration motor, and the measurement means And a preset threshold value, and when the measured leakage current value exceeds the threshold value, there is provided control means for controlling to drive the vibration motor.
By adopting this configuration, when the leakage current exceeds a threshold value, vibration is generated by the vibration motor. For this reason, the worker using the clamp tester can recognize that the leakage current is instantaneously large. In particular, since the clamp tester performs measurement while the operator holds the main body, the vibration is reliably recognized by the operator.

Further, a display means for displaying the leakage current value measured by the measurement means is provided, and a comparison mode for controlling the vibration motor by executing a comparison operation between the measured leakage current value and the threshold in the control means, There may be provided switching means for switching between a normal mode in which the leakage current value is simply displayed on the display means without comparing the measured leakage current value and the threshold value.
According to this configuration, when there is no great influence when the threshold value is exceeded, it can be used by switching to the normal mode in which the leakage current value is simply measured and displayed.

  Moreover, it is good also as providing the change means to change the value of the said threshold value. Thereby, it is possible to recognize the magnitude of the leakage current value at various values depending on the difference in the measurement site.

Further, a warning sound output means for outputting a warning sound is provided, and the control means controls to drive the vibration motor when the leakage current value measured by the measuring means exceeds a threshold value, and the warning sound. Control may be made to output a warning sound from the generator.
According to this configuration, since the sound is generated in addition to the vibration, the operator can surely recognize the magnitude of the leakage current value.

Further, the control means controls to drive the vibration motor when the leakage current value measured by the measuring means exceeds a threshold value, and the leakage current value displayed on the display means is blinked. It is good also as controlling.
According to this configuration, since it can be visually confirmed in addition to the vibration, the operator can surely recognize the magnitude of the leakage current value.

  According to the clamp tester of the present invention, the operator can be surely recognized the magnitude of the leakage current value.

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings.
First, the external appearance structure of the clamp tester of this embodiment is shown in FIGS.
The clamp tester 30 is configured by providing a ring-shaped clamp portion 32 at the tip of a substantially rectangular parallelepiped body portion 31. The clamp part 32 is divided in a semicircular shape in the middle part, and one of the divided parts rotates on the main body part 31 side, so that the clamp part 32 opens in a C shape.
The main body 31 is large enough to be gripped by the operator's hand, and has a display 34 (display means in the claims), an operation key 36 of the display 34, a mode changeover switch 38 on the surface. Is arranged. The mode changeover switch 38 is for switching on / off the power source and the current level to be measured, and is different from the switching means in the claims.

  The display unit 34 uses an LCD. However, the configuration of the display unit 34 is not particularly limited to the LCD. The operation key 36 of the display unit 34 has a COMP key 39 and a DH key 40. The function of these keys will be described later.

  The mode switch 38 is a rotary switch that also serves as a power switch. The mode changeover switch 38 is assigned with each mode of power off, current mA, current A, and voltage V. The mode changeover switch 38 is formed in a circular shape in plan view, and is arranged so that a part 38 a of the end face slightly protrudes outward from the side face of the main body 31. With this arrangement, the operator can easily operate the mode changeover switch 38 with one finger.

Further, a lever 42 for opening and closing the clamp portion 32 is provided on the side surface on the distal end side of the main body portion 31. The lever 42 is provided so as to have a position and size that can be operated by a hand held by an operator.
When the lever 42 is operated in the direction of the broken line arrow in FIG. 1, either one of the divided clamp portions 32 rotates about the main body 31 side as an axis, and the divided portion opens (broken line in FIG. 1). In this way, the electric wire can be accommodated inside the circle of the clamp portion 32 while being a live wire.

The end surface of the rear end side of the main body portion 31, an input terminal 44 of the AC voltage measurement is provided. Thus, when measuring an alternating voltage with the clamp tester 30 of this embodiment, without using the clamp part 32, it connects with an electric wire directly and performs a measurement.

Next, the schematic internal configuration of the present embodiment will be described with reference to FIG.
Inside the clamp tester 30, a measuring means 46 for measuring a leakage current, a vibration motor 48, a vibration motor drive circuit 49 for driving the vibration motor 48, and a control signal a is output to the vibration motor drive circuit 49 for vibration. A control unit 50 that controls driving of the motor 48 and a display unit 51 that displays a leakage current value measured by the measurement unit 46 are provided.

Specifically, the measuring unit 46 includes a head core 53 disposed inside the clamp portion 32 and a current measuring circuit 54 that measures a current value generated by a magnetic field passing through the head core 53.
The head core 53 includes two magnetic cores 55 formed in a substantially semicircular shape, and a coil 56 wound around the magnetic cores 55.
The head core 53 is disposed on both of the divided clamp portions 32, and is magnetically coupled to form a ring-shaped core when the clamp portion 32 is closed.
And by arranging the electric wire which is a live wire inside the circle of the clamp part 32 when measuring the leakage current, a magnetic field accompanying the leakage current of the electric wire is generated along the circumference of the clamp part 32. The magnetic core 55 of the head core 53 forms a magnetic path through which the magnetic lines of magnetic field pass, and a current flows through the coil 56.
This current is input to the current measurement circuit 54, and the current value is measured.

The control unit 50 includes a CPU 58 and a storage unit 59 including a ROM, a RAM, and the like. In the storage unit 59, a current value threshold value for driving the vibration motor 48 is stored in advance.
Note that the current value input to the control means 50 is the current value of the head core 53 and is different from the actual leakage current value. Since the current value is caused by the number of turns of the coil of the head core 53, the control means 50 converts the input current value of the head core 53 into an actual leakage current value based on the number of turns of the head core 53. It has a function.
The current value input to the control means 50 is an analog value. The control means 50 has an A / D converter function, and converts the current value input as an analog value into a digital value.

The control unit 50 has a comparison function (comparator) that compares the measured leakage current value with the threshold value stored in the storage unit 59. If the measured leakage current value is larger than the threshold value stored in the storage means 59 as a result of comparison by the comparison function of the control means 50, the vibration motor drive circuit 49 is driven to drive the vibration motor 48. A drive signal is output.
Note that the control means 50 of the present embodiment uses the vibration motor drive circuit 49 to drive the vibration motor 48 when the measured leakage current value is 0.01 mA or more larger than the threshold value stored in the storage means 59. A drive signal is output with respect to.

Here, an example of the structure of the vibration motor will be described (not shown).
The vibration motor includes a motor body and a weight attached eccentrically with respect to the rotation shaft of the motor body. The vibration motor rotates the rotating shaft when a drive current is input by the vibration motor drive circuit. Then, vibration is generated by the weight eccentrically attached to the rotating shaft of the motor body.
However, the vibration motor is not limited to such a structure.

  The vibration of the vibration motor 48 may be controlled to be intermittent. For example, the state of 1 second vibration and 1 second vibration is repeatedly performed. This control can be performed by controlling the output timing of the control signal from the control means 50 to the vibration motor drive circuit 49.

  Further, the mode changeover switch 38 and the operation key 36 of the display unit 34 are connected to the control means 50. The control means 50 switches the measurement mode based on a switching signal from the mode switch 38.

Further, the threshold value stored in the storage means 59 can be changed by the operator operating the operation key 36. This changing method will be described with reference to FIG.
First, the operator switches the mode changeover switch 38 to the current mA measurement mode. Then, the operator keeps pressing the COMP key 39 for a predetermined time (for example, 0.5 seconds). Then, the control means 50 shifts the display content on the display unit 34 to the setting mode as shown in FIG.

At this time, the threshold value is displayed on the display unit 34. The operator can set a new threshold value by changing the value displayed on the display unit 34 one digit at a time.
The digit selected on the display unit 34 is blinking. The operator can raise the selected digit by one by pressing the COMP key 39. The operator sets the number of digits selected on the display unit 34 to a desired number, and then presses the DH key 40 to shift the selected digit to the next digit.
After all the digits have been set, when the DH key 40 is kept pressed for a predetermined time (for example, 1 second), the set numerical value is stored in the storage means 59 as a threshold value.

The controller 50 may be connected with a buzzer 57 that is a warning sound generator.
As a result of comparison by the comparison function of the control means 50, when the measured leakage current value is larger than the threshold value stored in the storage means 59, the control means 50 outputs the output signal b to the buzzer 57. The buzzer 57 generates a warning sound according to an output signal from the control means 50. Specifically, when the measured leakage current value is 0.01 mA larger than the threshold value stored in the storage unit 59, the control unit 50 outputs the output signal b to the buzzer 57.

As described above, when the measured leakage current value is larger than the threshold value, in addition to generating vibration by the vibration motor 48 and generating a warning sound by the buzzer 57, the leakage current is less than the threshold value for the operator. Can be recognized with certainty.
The generation of the warning sound by the buzzer 57 may be controlled to be performed intermittently. For example, the generation of a 1-second warning sound and the generation stop of the 1-second warning sound are repeatedly performed.

Further, when the comparison function of the control unit 50 compares and the measured leakage current value is larger than the threshold value stored in the storage unit 59, the display of the leakage current value on the display unit 34 blinks. The control means 50 may also control.
Specifically, the control means 50 controls so that the display of the measurement result of the leakage current value on the display unit 34 is displayed by repeating lighting for 1 second and turning off for 1 second.

It should be noted that a threshold value stored in the storage unit 59 may be confirmed by operating the operation key 36.
Specifically, if the leakage current is being measured, the control unit 50 outputs the threshold value in the storage unit 59 to the display unit 34 and displays it on the display unit 34 by pressing the COMP key 39 for 0.5 seconds. .

The measured leakage current value as described above is compared with a threshold value, and control for generating vibration is set as a comparison mode. And control which only displays the measured leakage current value on the display part 34 without comparing with a threshold value is set as a normal mode.
In the present embodiment, switching means for switching between the comparison mode and the normal mode is provided.
Specifically, as a control program for operating the CPU of the control means 50, a program for executing the comparison mode and a program for executing the normal mode are stored, and these control programs are executed in accordance with instructions from the operator. Switch.

Specifically, the COMP key 39 is used as the switching means. When the operator switches between the comparison mode and the normal mode, the operator presses the COMP key 39 for a predetermined time (for example, 1 second). Then, in the control means 50, the measurement is executed based on another control program instead of the control program executed until now at the time of measurement.
Thus, the operator can easily switch between the comparison mode and the normal mode, and can engage in a more comfortable leakage current measurement operation.

  While the present invention has been described in detail with reference to a preferred embodiment, the present invention is not limited to this embodiment, and it goes without saying that many modifications can be made without departing from the spirit of the invention. .

It is a top view of the clamp tester of the present invention. It is a rear view of the clamp tester of FIG. It is a side view of the clamp tester of FIG. It is a block diagram explaining the internal structure of the clamp tester of this invention. It is explanatory drawing explaining the display state of a display part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 30 Clamp tester 31 Main part 32 Clamp part 34 Display part 36 Operation key 38 Mode changeover switch 39 COMP key 40 DH key 42 Lever 44 Input terminal 46 Measuring means 48 Vibration motor 49 Vibration motor drive circuit 50 Control means 51 Display part 53 Head core 54 Current measuring circuit 55 Magnetic core 56 Coil 57 Buzzer 59 Memory means

Claims (5)

In a clamp tester that measures the leakage current of a wire by clamping the wire,
Measuring means for measuring leakage current;
A vibration motor;
Control means for comparing the leakage current value measured by the measuring means with a preset threshold value and controlling the vibration motor to be driven when the measured leakage current value exceeds the threshold value. Clamp tester characterized by Display means for displaying the leakage current value measured by the measuring means is provided,
In the control means, a comparison mode for controlling the vibration motor by executing a comparison operation between the measured leakage current value and the threshold value, and simply displaying the leakage current value without comparing the measured leakage current value and the threshold value. 2. A clamp tester according to claim 1, further comprising switching means for switching between the normal mode displayed on the means.   3. The clamp tester according to claim 1, further comprising changing means for changing the value of the threshold value. A warning sound output means for outputting a warning sound is provided,
The control means controls to drive the vibration motor and to output a warning sound from the warning sound generator when the leakage current value measured by the measuring means exceeds a threshold value. The clamp tester according to any one of claims 1 to 3.   The control means controls to drive the vibration motor when the leakage current value measured by the measurement means exceeds a threshold value, and causes the leakage current value displayed on the display means to blink. The clamp tester according to any one of claims 2 to 4, wherein the clamp tester is controlled.

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