JPH06174754A - Wide range current sensor - Google Patents

Abstract

PURPOSE:To provide a wide range current sensor which can deal with different rated currents while reducing secondary current and which allows any one of normal machine or emergency machine to be inspected without interrupting operation of the other machine. CONSTITUTION:The current detector for detecting flux induced by AC current flowing through a conductor 1 and producing an output proportional thereto comprises a doughnut type core 2 passing a conductor 1 for which AC current is measured, a coil wire 3 wound around the core 2 by n2 turns, a resistor 5 connected between the opposite ends of the coil wire 3, and a gain switcher 6 for switching the voltage level across the resistor 5 into a desired level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects an alternating current flowing through a conductor, detects a current flowing proportionally by a magnetic flux generated proportionally by the current, and outputs an output proportional to the current flowing through the conductor. It is about.

[0002]

2. Description of the Related Art An example of a conventional current detecting device will be described below with reference to the drawings. Fig. 4 shows the detection principle of a current detection device using a through-type current transformer. A doughnut-shaped core is made to penetrate a conductor through which an alternating current to be measured is passed, and the magnetic flux is proportionally generated by the current. The current flowing in the conductor is detected and an output proportional to the current flowing in the conductor is output. In the figure, 1 is a conductor through which an alternating current to be measured flows, and 2 and 3 are through-type current transformers.
Is a doughnut-shaped core arranged so as to pass through the conductor 1 through which the measured alternating current flows, and 3 alternately passes inside / outside the outer circumference of the core in a direction perpendicular to the doughnut-shaped surface of the core 2. It is a coil wire that is spirally wound n ₂ times as shown in FIG. Reference numeral 4 denotes an impedance Z ₁ (Z ₁ which becomes a burden on the current transformer connected to both ends of the coil electric wire 3.
The load 4 is a load having <<, and the load 4 is configured by series connection of an ammeter or the like used in a steady state and an overcurrent protection relay used in a non-steady state.

Next, the operation will be described. In an ideal current transformer, the conductor 1 through which the measured alternating current i ₁ flows penetrates the doughnut-shaped core 2 (in the figure, the number of penetrations n ₁ is once).
By doing so, a magnetic flux Φ ₁ is generated in the right-hand screw direction in proportion to the measured alternating current i ₁ with respect to the flowing direction of the measured alternating current i ₁ so as to draw a donut ring in the doughnut-shaped core 2. .

Magnetic flux Φ ₁ generated in the doughnut-shaped core 2
Accordingly, a current i ₂ proportional to the measured alternating current i ₁ flows in the coil electric wire 3 in a direction to cancel the magnetic flux Φ ₁ , and outputs it to the load 4.

Therefore, as the current transformer, the current i ₂
Is output.

[0006]

The through-type current transformer, which is the conventional current detecting device described above, has the following problems because it is configured as described above.

For example, in the case where the output from 0 A to 5 A between the measured AC current i _{1 and} 0 A is the rated current,
Ideally, the number of turns n ₂ of the coil wire 3 is (n ₁ × i ₁ /
5) As the number of turns, the number of turns of the coil wire 3 is n _{2 for} each rated current.
Therefore, there was a type for each rated current of the measured alternating current i ₁ .

Further, since it is necessary to change the winding number n ₂ of the coil wire 3 for each rated current of the measured alternating current i ₁ ,
The sizes were also not the same.

A large current of 5 A, for example, flows through a load 4 having an impedance Z ₁ (Z ₁ <<) connected to both ends of the coil electric wire 3, which is a burden on the current transformer, and thus has a large heat capacity. Had to use.

Further, the coil wire 3 and the impedance Z ₁
A large current of 5 A, for example, flows through the circuit composed of the load 4 having (Z ₁ <<).
It was not possible to place adjacent equipment that is susceptible to noise or parallel wiring of electric wires through which a weak current flows.

There is one type of output. For example, in the steady state, the measured AC current i ₁ is between 0 A and the rated current, and 0 A to 5 A is output as the current i ₂ , and in the steady state, the measured AC current i 1
₁ exceeds the rated current and outputs 5A or more as the current i ₂ , and the load 4 has an ammeter etc. used in the steady state and an overcurrent protection relay used in the non-steady state. Use the test terminals when operating the equipment to be used during unsteady conditions when inspecting equipment, and when operating the equipment to be used during steady operation when inspecting equipment to be used during non-stationary operations. It was necessary to take measures such as doing.

The output is N of the rated current of the measured alternating current i _1.
In the case of proportionally up to twice, it is necessary to change the vertical cross-sectional area with respect to the donut-shaped surface of the donut-shaped core 2 in consideration of the magnitude of the impedance Z ₁ of the load 4. There was a type for each rated current of the measured alternating current i ₁ , and the magnitudes were not the same.

The present invention has been made in order to solve the above-mentioned problems, and one type can deal with various rated currents, has a small secondary current, and is a device for steady-state use or an emergency. The purpose of the present invention is to provide a wide-range current sensor that does not require the operation of one of the devices to be stopped when inspecting the device.

[0014]

A wide-range current sensor according to the present invention has a doughnut-shaped core arranged so that a conductor through which an alternating current i _{1 to} be measured flows and a donut-shaped core. Coil wire 3 spirally wound n ₂ times so as to alternately pass inside / outside of the outer periphery of the core in the vertical direction with respect to the plane, the resistance connected to both ends of the coil wire, and It is composed of a gain switcher that inputs voltage and switches to the required output level with a selector switch.

Even when the required output level is changed, the ratio of the number of times the conductor through which the alternating current i _{1 to} be measured passes through the core and the number of windings of the coil wire around the core (n ₁ to n ₂ )
Does not change and remains constant.

The ratio of the number of times the conductor through which the measured alternating current i ₁ passes through the core to the number of windings of the coil wire around the core (n ₁
The pair n ₂ ) is set to 1: 1000 or more.

[0017] For inter rated current from the measurement alternating currents i ₁ is 0A, and the output 2 to proportionally output until a certain value from a certain value, the measurement alternating currents i ₁ is the rated current from 0A N It is provided with an output 1 that proportionally outputs from a certain value to a certain value with respect to a multiple, and a gain switcher that can set a rated current of the measured alternating current i ₁ by a changeover switch.

[0018] For inter rated current from the measurement alternating currents i ₁ is 0A, and the output 2 to proportionally output until a certain value from a certain value, the measurement alternating currents i ₁ is the rated current from 0A N Output 1 that outputs proportionally from a certain value to a certain value for the doubled time and the rated current of the measured alternating current i ₁ can be set by the changeover switch II, and the N value can be changed over.
It has a gain switch that can be set by I.

[0019]

Operation Even when the measured AC current i ₁ is changed from a certain value to a certain value in the range from 0 A to the rated current, it is not necessary to change the number of windings of the coil wire for each rated current, and the winding of the coil wire is not required. The number of times n ₂ is constant and the size can be the same, and it is not necessary to have a type of the measured alternating current i ₁ for each rated current.

The resistance connected to both ends of the coil wire is
Only a small current of about several mA can be applied, and a small heat capacity can be used.

In addition, a current consisting of a coil wire and a resistor can be made to flow only a small current of about several mA, so that a device vulnerable to noise is arranged adjacent to the circuit or an electric wire through which a weak current flows. Parallel wiring is possible.

Use test terminals when making use of equipment used at non-steady-state during inspection of equipment used at steady-state and when making use of equipment used at steady-state at inspection of equipment used at non-steady-state It is not necessary to make each device a drawer type.

Even when the output is proportionally output up to N times the rated current, it is not necessary to change the vertical sectional area of the donut-shaped surface of the donut-shaped core, and the donut-shaped core donut is not required. in the cross-sectional area in the vertical direction with respect to that plane in the form constant, can the size be the same, the measured alternating current i ₁
The type for each rated current of is not required.

[0024]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. FIG. 1 shows the current detection principle of the wide-range current sensor according to this embodiment. A donut-shaped core is made to penetrate a conductor through which an alternating current to be measured is passed, and the magnetic flux proportionally generated by the current causes proportionality. The current flowing through the conductor is detected, and an output proportional to the current flowing through the conductor is output. In the figure, 1 is a conductor through which an alternating current to be measured flows, 2, 3, 5 and 6 constitute a wide-range current sensor, and 2 is a donut arranged so that a conductor 1 through which an alternating current to be measured flows. The core 3 of the shape is spiral 20 so as to alternately pass inside / outside the outer circumference of the core in the vertical direction with respect to the doughnut-shaped surface of the core 2.
It is a coil electric wire wound 00 times (n ₂ = 2000).
Further, 5 is a resistor having resistance R (R <<) connected to both ends of the coil electric wire 3, 6 is input voltage across the resistor 5, and the measured alternating current is from 0 A to the rated current. Output 2 that outputs proportionally from a certain value to a certain value and the measured AC current from 0 A to the rated current x 20 times (N =
20) Outputs two kinds of output, that is, the output 1 which is proportionally output from a certain value to a certain value, and internally has a changeover switch for setting the required output level for the outputs 1 and 2. It is a gain switch. Further, 4a is an impedance Z ₂₁ (Z ₂₁ << for current output, << Z for voltage output, which becomes a burden of the output 1 of the wide range current sensor.
₂₁ ), a load 4b is a load having an impedance Z ₂₂ (Z ₂₂ << for current output, <<<< Z _{22 for} voltage output) that is a burden of the output 2 of the wide range current sensor, and the load 4a. Is configured in series connection if the overcurrent protection relay used in non-steady state is current output, or in parallel connection in the case of voltage output, and the load 4b is configured as current output of the ammeter used in steady state. Series connection, parallel connection for voltage output.

FIG. 2 is an internal circuit diagram of the gain switcher 6 described in FIG. 1, in which the voltage across the resistor 5 is input, two types of outputs, outputs 1 and 2, are output, and the outputs 1 and 1 are internally provided. Two
It has a change-over switch for setting the required output level. In the figure, 6a is a changeover switch circuit for setting the rated current of the alternating current to be measured, and as shown in the figure, the changeover switch circuit 6a has resistors r _i11 , r _i12 , r _i13 , r.
_i14 , r _f1 , switches S ₁₂ , S ₁₃ , S ₁₄ , operational amplifier O
It is composed of P ₁ . Further, 6b is an N value defining circuit that defines an N value for proportionally outputting a value between a certain value and a certain value from 0 A of the measured alternating current to the rated current x N times, and is switched as shown in the figure. The switch circuit 6b includes resistors r _i31 , r _f31 , r _i32 , r _f32 , an operational amplifier OP ₃₁ ,
It consists of OP ₃₂ . By setting 6a, that is, by opening and closing switches S ₁₂ , S ₁₃ , and S ₁₄ , for example, the measured AC current at output 2 outputs 0V to 6V _rms between 0A and the rated current, and the measured AC at output 1 From 0V to 6 times the rated current x 20 times (N = 20) from 0A
_Vrms can be output.

Next, the operation will be described. The conductor 1 through which the alternating current i _{1 to} be measured passes through the doughnut-shaped core 2 (the number of penetrations n ₁ is once in the figure), so that the donut ring is drawn in the toroidal core 2 to be measured. flux [Phi ₁ proportionally to the measured AC current i ₁ is generated in the right screw direction to the direction of flow of the alternating current i _1.

Magnetic flux Φ ₁ generated in the doughnut-shaped core 2
Accordingly, a current i ₂ flows in the coil wire 3 in a direction in which the magnetic flux Φ ₁ is canceled in proportion to the measured alternating current i ₁ , and a voltage proportional to the current i ₂ is generated across the resistor 5.

A voltage proportional to the current i ₂ generated at both ends of the resistor 5 is input to the gain switching device 6 and, for example, the output 2 is output by the switching switch circuit 6a and the n value defining circuit 6b.
Then, the measured AC current i ₁ is output from 0 V to 6 V _rms between 0 A and the rated current to the load 4b. At the output 1, the measured AC current i ₁ is 0 A to the rated current × 20 times (N = 2).
0V to 6V _rms is output to the load 4a for the period 0).

Therefore, the current i ₂ proportional to the measured alternating current i ₁ is detected and set to the required output level for the outputs 1 and 2, for example, 0 V to 6 V _rms are output. .

Here, for example, the measured alternating current i ₁ is 0
Relative inter rated current from A, as 6V _rms output from 0V, if the measured AC current i ₁ is relative between the rated current × N times from 0A, and 6V _rms output from 0V, the changeover switch Since the rated current can be set by the circuit 6a and the N value is defined by the N value defining circuit 6b, the number of windings of the coil wire 3 and the donut shape of the doughnut-shaped core 2 are defined for each rated current of the measured alternating current i _1. It is not necessary to change the vertical cross-sectional area with respect to the surface being shaped.

Example 2. The second embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows the internal circuit of the gain switcher 6 described in FIG. 1, in which the voltage across the resistor 5 is input and the output 1
It outputs two kinds of output, that is, 2 and internally has a changeover switch for setting an output level required for the outputs 1 and 2. In the figure, 6a is a changeover switch circuit II for setting the rated current of the measured alternating current, and as shown in the figure, the changeover switch circuit 6a has resistors r _i11 , r _i12 , r _i13 , r
_i14 , r _f1 , switches S ₁₂ , S ₁₃ , S ₁₄ , operational amplifier O
It is composed of P ₁ . Further, 6c is a changeover switch circuit for setting an N value for proportionally outputting from 0 A of the measured alternating current to the rated current x N times from a certain value to a certain value.
As shown in the figure, the changeover switch circuit 6c is composed of resistors r _i21 , r _i22 , r _i23 , r _i24 , r _f2 , switches S ₂₂ , S ₂₃ , S ₂₄ , and an operational amplifier OP ₂ . Depending on the setting of the changeover switch circuit 6a and the changeover switch circuit 6c, for example, the output 2 outputs 0V to 6V _rms between the measured AC current and the rated current, and the output 1 outputs the measured AC current from 0A to the rated value. 0V to 6V _rms can be output for the current × N times.

Next, the operation will be described. In FIG. 1, a conductor 1 through which an alternating current i _{1 to} be measured flows through a doughnut-shaped core 2 (in the drawing, the number of penetrations n ₁ is once), so that a donut ring is drawn in the doughnut-shaped core 2. flux [Phi ₁ is generated in proportion to the measured AC current i ₁ to the right screw direction with respect to the flowing direction of the measurement alternating currents i ₁ as.

Magnetic flux Φ ₁ generated in the doughnut-shaped core 2
Accordingly, a current i ₂ flows in the coil wire 3 in a direction in which the magnetic flux Φ ₁ is canceled in proportion to the measured alternating current i ₁ , and a voltage proportional to the current i ₂ is generated across the resistor 5.

A voltage proportional to the current i ₂ generated at both ends of the resistor 5 is input to the gain switch 6, and the changeover switch circuits 6a and 6c allow the measured alternating current i ₁ to be rated from 0 A at the output 2, for example. 0V to 6V _rms for current
Is output to the load 4b, and at the output 1, the measured AC current i ₁
Is 0V to 6V _rms for rated current × N times
Is output to the load 4a.

Therefore, the wide range current sensor detects a current i ₂ which is proportional to the measured alternating current i ₁ and sets it to the required output level for outputs 1 and 2, for example, 0V to 6V, respectively. Outputs in _rms .

Here, for example, the measured alternating current i ₁ is 0
Relative inter rated current from A, and 6V _rms output from 0V, if the measured AC current i ₁ is relative between the rated current × N times from 0A, and 6V _rms output from 0V, the switching Since the rated current can be set by the switch circuit 6a and the N value can be set by the changeover switch 6c, the number of windings of the coil electric wire 3 and the donut shape of the doughnut-shaped core 2 can be set for each rated current of the measured alternating current i _1. It is not necessary to change the vertical cross-sectional area with respect to the plane.

Example 3. In the first and second embodiments and the conventional example, the through-type current detecting device in which the conductor 1 through which the measured alternating current i ₁ flows passes through the doughnut-shaped core 2 has been described, but the measured alternating current i ₁ is the donut-shaped one. The same effect can be obtained with a winding type in which the core 2 is penetrated n ₁ times.

Example 4. In the first and second embodiments, the outputs 1 and 2 are described as voltage outputs, but the same effect can be obtained even if the output form is current, frequency, or the like.

[0040]

As described above, the present invention has the following effects.

Even when the measured AC current i ₁ is changed from a certain value to a certain value in the range from 0 A to the rated current, it is not necessary to change the number of windings of the coil wire 3 for each rated current. The number of windings n ₂ can be made constant and the size can be made the same, and there is no need for the type of the measured alternating current i ₁ for each rated current.

The resistance connected to both ends of the coil wire 3 can be made to flow only a small current of about several mA,
The one with a small heat capacity can be used.

In addition, the circuit constituted by the coil wire 3 and the resistor can be made to flow only a small current of about several mA, and adjacent to the circuit, a device vulnerable to noise is arranged adjacent to the circuit or a weak current flows. Parallel wiring can be done.

Use the test terminals when making use of the equipment used at non-steady-state during inspection of the equipment used at steady-state and when making use of the equipment used at steady-state at the time of inspection of equipment used at non-steady-state There is no need to make each device a drawer type.

Even when the output is proportionally output up to N times the rated current, it is not necessary to change the vertical cross-sectional area of the donut-shaped surface of the donut-shaped core 2, and the donut-shaped core 2 is not required. The cross-sectional area in the vertical direction with respect to the doughnut-shaped surface can be made constant and the size can be made the same, and there is no need for the type of the measured alternating current i ₁ for each rated current.

[Brief description of drawings]

FIG. 1 is a diagram showing a current detection principle of a wide range current sensor according to an embodiment of the present invention.

FIG. 2 is an internal circuit diagram of a gain switcher of the wide range current sensor shown in FIG.

FIG. 3 is an internal circuit diagram of another gain switcher of the wide range current sensor shown in FIG.

FIG. 4 is a diagram showing a current detection principle of a conventional through-type current transformer.

[Explanation of symbols]

1 Conductor to be measured AC current 2 Donut-shaped core 3 Coil wire wound around core 4 Impedance Z ₁ connected to both ends of coil wire
Load 4a Load having impedance Z ₂₁ that becomes the output load of the wide range current sensor Load 4b Load having impedance Z ₂₂ that becomes output 2 of the wide range current sensor 5 Resistance 5 connected to both ends of the coil wire Resistor 6 Gain switcher 6a Changeover switch circuit for setting the rated current of the measured alternating current 6b Proportional output from 0 A of the measured alternating current to the rated current × N times from a certain value to a certain value N N value defining circuit that defines the value 6c Changeover switch circuit that sets the N value that proportionally outputs from 0 A of the measured alternating current to the rated current x N times from a certain value to a certain value

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Michio Sakai 8 Horai-cho, Marugame-shi, Kagawa Mitsubishi Electric Corporation Marugame Plant (72) Inventor Hiroshi Numakura 2-14-40 Ofuna, Kamakura-shi, Kanagawa Mitsubishi Electric Corporation Company Life Systems Research Center

Claims (5)

[Claims] 1. An AC current to be measured in a current detecting device, which detects an AC current flowing through a conductor proportionally by a magnetic flux generated proportionally by the current and outputs an output proportional to the current flowing through the conductor. Doughnut-shaped core that is arranged so that the conductor that flows through the core and the inside of the core outer periphery in the direction perpendicular to the donut-shaped surface of the core
A coil wire that is spirally wound n ₂ times so as to alternately pass through the outside, a resistor connected to both ends of the coil wire, and a voltage at both ends of the resistor are input to change the output level to a required level by a switch. A wide-range current sensor characterized by being configured with a gain switching device that performs switching. 2. The wide-range current sensor according to claim 1, wherein even when the required output level is changed, the number of times the conductor through which the alternating current to be measured passes through the core and the number of windings of the coil wire around the core are determined. A wide-range current sensor characterized by keeping the ratio constant without changing. 3. The wide range current sensor according to claim 2, wherein the ratio of the number of times the conductor through which the alternating current to be measured passes through the core and the number of times the coil wire is wound around the core is set to 1:10.
A wide-range current sensor characterized by having a value of 00 or more. 4. The wide-range current sensor according to claim 1, wherein an AC current to be measured is output proportionally from 0 A to a rated current from a certain value to a certain value; Output 1 that outputs proportionally from a certain value to a certain value for AC current from 0A to N times the rated current, and a gain switcher that can set the rated current of the measured AC current with a changeover switch. A wide-range current sensor characterized by being equipped. 5. The wide-range current sensor according to claim 1, wherein an alternating current to be measured is proportionally output from a certain value to a certain value between 0 A and the rated current, and the measured current. Output 1 that outputs proportionally from a certain value to a certain value for AC current from N times the rated current and rated current of the measured AC current can be set by changeover switch II. A wide-range current sensor, which is equipped with a gain switch that can be set by the changeover switch I.