JPH11295345A - Clamp ammeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a clamp ammeter in which the operating procedure of current measurement is reduced. SOLUTION: A clamp ammeter 10 for measuring a current flowing through a wire by passing the wire through an annular opening/closing core 20 is provided with a power supply control means for turn on power when the core 20 is opened to pass a wire and turns off power when the core 20 is opened to remove the wire after measurement. The power supply control means switches the state where power is turned on or off alternately every time when the core 20 is opened and holds the state of power supply until the core 20 is opened next. Consequently, power is turned on when the core is opened to pass a wire and turned off when the core is opened again to remove the wire after measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a clamp-type ammeter for measuring a current without opening a circuit.

[0002]

2. Description of the Related Art As a method of measuring a current in a wiring state without opening a circuit, a clamp-type ammeter for measuring a magnetic field generated from a current of the circuit and obtaining the current is often used. This clamp-type ammeter can be briefly described as follows: For example, a coil is wound around a circular iron core that can be opened and closed, and when the opening and closing part is opened, an electric wire is passed through. Since a voltage is generated at this point, the current can be obtained by reading this voltage with a meter. Then, for example, when the measured value is digitally displayed, as shown in FIG. 3, the voltage generated in the coil 42 is amplified by the amplifier 60, then converted into a digital signal by the A / D converter 62, and the digital display is performed. The current value is displayed by the heater 64.

[0003]

However, a separate power supply 52 is required to perform signal amplification and signal display, and it is necessary to close the power switch 50 and turn on the power during measurement. When the measurement is completed, the power switch 5
It is necessary to open 0 and return to the power-off state. That is, at the time of measurement by the clamp-type ammeter, an operation for turning on the power and an operation for turning off the power are separately required. For this reason, the number of operations required for the measurement increases, and the work efficiency of the measurement deteriorates. In addition, there arises a problem that the power supply is forgotten after the measurement and power is wasted.

The inventor of the present invention has conducted intensive studies to solve such problems, and as a result, has arrived at the present invention.

[0005]

The gist of the clamp-type ammeter according to the present invention is to provide a clamp-type ammeter for measuring a current flowing through an electric wire through an electric wire in an openable and closable iron core. Power supply control means for turning on the power when the annular core is opened in the closed state, and for turning off the power when the annular core is opened while the power is on.

The gist of the clamp-type ammeter according to the present invention is as follows. The power control means detects that the annular core has been opened, and the detector has opened the annular core. And a switch unit that alternately switches between a power-on state and a power-off state each time the power supply is detected.

The gist of the clamp-type ammeter according to the present invention resides in that the power supply control means keeps the state of the power supply until the annular core is next opened.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a clamp type ammeter according to the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a clamp type ammeter 10 according to the present invention.
A main unit 4 having a display unit 16 for displaying measured values and the like, a range changeover switch 6 for changing over a measurement range, function setting switches 7 and 8 for changing over various settings and functions, and a ring that can be opened and closed. And an iron core 20. As shown in FIG. 2, the annular core portion 20 includes a fixed core portion 22 fixed to the main body portion 4 and an opening / closing operation portion 12.
Is pressed, the movable core 24 rotates about the rotation shaft 26.
The opening / closing section 14 can be freely opened (closed) by holding down (stopping holding down) the opening / closing operation section 12.

A power supply control means 30 is provided in the annular core 20 and its peripheral portion for alternately switching between a power-on state and a power-off state each time the opening / closing section 14 is opened. Therefore, when the annular core 20 is opened and the electric wire to be measured is inserted, the power is turned on and the annular core 20
Can be returned to the power-off state by reopening and taking out the electric wire. For example, as shown in FIG. 2, the power supply control unit 30 can be provided so as to come into contact with the opened and closed operation unit 12 when the annular core unit 20 is opened.

The power supply control means 30 includes the annular core 20
Is a switch for turning on / off the power by contact with the open / close operation unit 12 when the switch is opened, and furthermore, the state of the power supply until the annular core portion 20 is opened and contacts the open / close operation unit 12 again. It has a function to hold. That is, when the annular core portion 20 is opened (the opening / closing operation portion 12 comes into contact with the power supply control means 30) and the power is turned on,
Even if the annular core part 20 is closed (the opening / closing operation part 12 is separated from the power control means 30), the power supply state is maintained, and then the annular core part 20 is opened (the opening / closing operation part 12 is connected to the power control means 30). Until the contact is made, the power-on state is maintained.

As the power control means 30, for example, a push button switch called an alternate switch or a self-lock switch, which mechanically holds a push state by one push and returns to an initial state when pushed again, may be used. it can. The switch provided with such a push button detects that the annular core portion 20 is opened when the button comes into contact with the opening / closing operation section 12 and is pressed, and each time the button is pressed, the switch is opened and closed. The state changes alternately. Therefore, for example, FIG.
When the button is pressed while the switch 50 is open (power off), the switch 50 is in a closed state while the button is pressed, as a matter of course.
After that, even if the button is released and pressed, the switch 50 is kept closed (power on). When the button is pressed again with the switch 50 closed (power on), the original switch 50 can be returned to the open state (power off).

Next, the operation of the clamp type ammeter 10 for measuring current will be described.

First, the opening / closing operation unit 12 is pushed to move the movable core 2
4 is rotated to open and close the opening / closing section 14. Then, as shown in FIG. 2, the opening / closing operation unit 12 comes into contact with the power control unit 30 and presses the button of the switch 50, and the switch 50 is closed and the power is turned on. Then, after the electric wire to be measured is put into the annular core portion 20, the opening / closing operation portion 12 is released, the movable core portion 24 is returned to the original state, and the opening / closing portion 14 is closed. In this case, the open / close operation unit 12 and the power control unit 30
Are not in contact with each other, and the button of the switch 50 is not pressed, but the switch 50 is kept closed. Therefore, the power is turned on, and the measured current value is displayed on the display unit 16.

When the measurement is completed, the opening / closing operation unit 12
Is pressed to open the opening / closing portion 14 and take out the electric wire outside the annular core portion 20. Then, as shown in FIG. 2, the opening / closing operation unit 12 comes into contact with the power supply control means 30 and presses the button of the switch 50, and the switch 50 is switched from the closed state to the open state. Become. This switch 50
Is held until the annular core 20 is opened next time and the button of the switch 50 is pressed.

Thus, the clamp-type ammeter 1 of the present invention
0 indicates that the power is switched on and off alternately each time the annular core 20 is opened, and the annular core 20
Is provided with a power supply control means 30 for maintaining the state of the power supply until it is opened next time. Therefore, when the annular core portion 20 is opened and the electric wire is put into the annular core portion 20, the power is turned on, and after the measurement, the annular core portion 20 is opened again and the power is turned off when the electric wire is taken out of the annular core portion 20. State can be returned. Thus, the operation of turning on the power before the measurement and the operation of turning off the power after the measurement can be automatically performed when the annular core portion 20 is opened. Therefore, the operation procedure is simplified, the work efficiency is improved, and at the same time, it is possible to prevent the user from forgetting to turn off the power after the work.

Since the clamp-type ammeter 10 of the present invention switches the power switch every time the annular core 20 is opened, the power is turned off when an electric wire is inserted into the annular core 20 in some cases. And the power may be turned on when the electric wire is pulled out. However, in such a case, the power may be turned on by opening and closing the annular core portion 20 again while keeping the electric wire in the annular core portion 20.

Although the embodiment of the present invention has been described above, the clamp-type ammeter according to the present invention can be implemented in other embodiments. For example, the power supply control means is not limited to an alternate switch or a self-locking switch.For example, a general push button switch that closes a switch only while a button is being pressed and a holding circuit using a flip-flop or the like are used. It is also possible to configure with. FIG. 4 shows an example of a power supply control means that combines a normal push button switch 54 and a switching holding circuit that alternately switches the power on / off state when the switch 54 is pressed and holds the power on state. is there. A microswitch or a reed switch is used as the switch 54, and a D flip-flop 56 and a transistor (Tr) 58 are used as a switching holding circuit.

In this power supply control means, Q is H (H
When (i.g., high), Qｉ (NOT Q) is L (Low), the power is turned off because Tr is off. Then, in this state, when the annular core portion 20 is opened and an electric wire is inserted, it comes into contact with the opening / closing operation portion 12 and the switch 54
Is pressed, and a signal is input to CLK. This gives Q
Since L and Q become H and Tr is turned on, the power is turned on. It should be noted that even if the switch 54 is opened with the annular core 20 closed, the D flip-flop 56
As a result, the power-on state is maintained. Then, when the annular core portion 20 is opened and the electric wire is drawn out after the measurement, the switch comes into contact with the opening / closing operation portion 12 again, the switch 54 is pressed, and a signal is input to CLK. Then, Q becomes H, Q￣ becomes L and T
Since r is turned off, the power is turned off.

As described above, it is also possible to constitute the power supply control means by combining the ordinary push button switch and the switching holding circuit (D flip-flop and transistor). Therefore, instead of the push button switch, a sensor such as a pressure sensor that can detect contact can be used to transmit a detection signal by contact with the opening / closing operation unit when the annular core is opened. That is, as the detection unit of the power supply control unit, any unit can be used as long as it can detect that the opening / closing unit (annular core unit) is opened or closed. Further, the switching holding circuit may be of any type as long as it can alternately switch between the ON state and the OFF state each time a signal is received from the outside, and can hold the state until the next switching. . Since it is necessary to connect a power supply to these holding circuits,
It is preferable to use one with low power consumption.

The detecting section can be provided at an arbitrary position. For example, the detecting section can be provided near the opening / closing section to transmit a signal each time the annular core is opened or closed, or can be provided near the rotating shaft. It is possible to detect the rotation of the movable iron core portion by providing. That is, as long as the power switch of the clamp-type ammeter can be switched by opening and closing the annular core, any power control means (detection unit, switch unit) can be used. These power control means can be provided in any clamp-type current measuring device.

Although the embodiments of the clamp-type ammeter according to the present invention have been described in detail with reference to the drawings, the present invention is not limited to the illustrated clamp-type ammeter. For example, it is also possible to switch on / off the power by detecting a short circuit of the iron core of the annular core part or an induced voltage when the iron core is opened. In addition, the present invention can be implemented in various modified, modified, and modified embodiments based on the knowledge of those skilled in the art without departing from the spirit of the present invention.

[0023]

According to the clamp-type ammeter of the present invention, each time the annular core is opened, the power is switched on and off alternately each time the annular core is opened. Power supply control means for maintaining the state is provided. Therefore, when the annular core is opened and the electric wire is put into the annular core, the power is turned on, and after the measurement, the annular core is opened again and the power is turned off when the electric wire is taken out from the annular core. Can be Thereby, the operation of turning on the power before the measurement and the operation of turning off the power after the measurement can be automatically performed when the annular core is opened. Therefore, the operation procedure is simplified, the work efficiency is increased, and at the same time, it is possible to prevent the user from forgetting to turn off the power after the work.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a clamp-type ammeter according to the present invention.

FIG. 2 is an enlarged explanatory view of a main part of the clamp-type ammeter shown in FIG.

FIG. 3 is a block diagram showing a circuit configuration of the clamp-type ammeter shown in FIG.

FIG. 4 is a block diagram showing another embodiment of the power supply control means of the clamp-type ammeter according to the present invention.

[Explanation of symbols]

 4: Body unit 6: Range changeover switch 7, 8: Function setting switch 10: Clamp type ammeter 12: Opening / closing operation unit 14: Opening / closing unit 16: Display unit 20: Annular core unit 22: Fixed core unit 24: Movable core unit 26: Rotating axis 30: Power control means 40: Electric wire 42: Coil 50: Switch (detection unit, switch unit) 52: Power supply 54: Switch (detection unit) 56: D flip-flop (switch unit) 58: Transistor (switch) Part) 60: amplifier 62: A / D converter 64: digital display

Claims (3)

[Claims] 1. A clamp-type ammeter for measuring a current flowing through an electric wire through an openable and closable annular core, wherein when the annular core is opened while the power is off, the power is turned on, and the power is turned on. A clamp-type ammeter comprising a power supply control means for turning off the power when the annular core is opened with the power on. 2. A power supply control unit, comprising: a detection unit for detecting that the annular core is opened; and a power-on state and a power-off state each time the detection unit detects that the annular core is opened. 2. The clamp-type ammeter according to claim 1, further comprising: a switch unit that alternately switches between a closed state and a closed state. 3. The clamp-type ammeter according to claim 2, wherein said power supply control means keeps a state of the power supply until said annular core is opened next time.