JP3072550U - Load current detection unit - Google Patents

Abstract

(57) [Problem] To provide a small and simple load current detection unit that can be easily housed in a distribution board or the like. SOLUTION: A load current IL of a load circuit 1 is a current transformer 1
0, input interface 20, rectifier circuit 3
The voltage is converted into a voltage S50 corresponding to the level by the integration circuit 40 and the buffer circuit 50. Voltage S50
Is supplied to comparators 61 to 65 of voltage comparison unit 60, and compared with reference voltages VR1 to VR5 corresponding to 100%, 75%, 50%, 25%, and 1% of load current IL, respectively.
The signals S61 to S65 of the comparison result are output. Signal S6
1 to S65 are given to the LEDs 71 to 75 in the display unit 70, and a display corresponding to the level of the load current IL is performed.
Since this load current detection unit can be composed entirely of a semiconductor circuit except for the current transformer 10, it can be easily housed in a distribution board or the like.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a load current detection unit for displaying a level of a load current flowing in a load circuit such as a distribution board.

[0002]

[Prior art]

 The conventional distribution board is provided with a circuit breaker for each of a plurality of load circuits, and is capable of performing automatic cutoff at the time of overload and manual cutoff for each load circuit. When performing maintenance of equipment connected to such a distribution board, it is necessary to operate the corresponding circuit breaker to cut off the power supply to the equipment. In a conventional distribution board, a circuit breaker corresponding to a target device is specified and a breaking operation is performed based on a name plate, a system diagram, and the like attached to the circuit breaker.

[0003]

[Problems to be solved by the invention]

 However, in the conventional general distribution board, since the ammeter is not inserted for each load circuit, the magnitude of the flowing load current cannot be known. For this reason, there is a possibility that the load circuit in operation may be interrupted by misidentifying the name plate or the system diagram. In addition, since analog measuring instruments such as ammeters are relatively large and expensive, it was difficult to accommodate an ammeter for each load circuit in a distribution board. The present invention solves the problems of the prior art and provides a small and simple load current detection unit that can be easily housed in a distribution board or the like.

[0004]

[Means for Solving the Problems]

 In order to solve the above-mentioned problem, the present invention provides a load current detection unit that detects a strength of a magnetic field generated by a load current and a level of the load current based on an output signal of the current sensor. A voltage generator for generating a voltage to be generated, a voltage comparator for comparing the voltage generated by the voltage generator with a plurality of reference voltages, and outputting a comparison result for each of the reference voltages; A display unit for displaying a level of the load current based on an output signal.

According to the present invention, since the load current detection unit is configured as described above, the following operation is performed. The strength of the magnetic field generated by the load current is detected by the current sensor and is provided to the voltage generator. The voltage generator generates a voltage corresponding to the level of the load current based on the output signal of the current sensor, and supplies the voltage to the voltage comparator. In the voltage comparison unit, a voltage corresponding to the level of the load current is compared with a plurality of reference voltages, and a comparison result for each reference voltage is output to the display unit. The display unit displays the load current level based on the comparison result for each reference voltage provided from the voltage comparison unit.

[0006]

[Embodiment of the invention]

 (First Embodiment) FIG. 1 is a configuration diagram of a load current detection unit showing a first embodiment of the present invention. The load current detection unit detects a load current IL flowing through a load circuit 1 such as an AC distribution board, and performs a display corresponding to the level, and detects an AC magnetic field generated by the load current IL. A current transformer 10 is provided as a current sensor for detecting intensity.

The current transformer 10 has a secondary winding 12 wound around a ring-shaped magnetic core 11, and a wiring of the load circuit 1 as a primary winding penetrates the center of the magnetic core 11. It is composed of The secondary winding 12 is connected to a voltage generator (for example, an input interface) 20. The input interface 20 terminates the secondary winding 12 with a resistance of, for example, 10 kΩ and converts the output signal of the current transformer 10 into a voltage. The output side of the input interface 20 is connected to the rectifier circuit 30.

The rectifier circuit 30 includes, for example, an operational amplifier 31, a diode 32, and a resistor 33, and rectifies an AC voltage to convert it into a DC voltage. The output side of the rectifier circuit 30 is connected to the integration circuit 40. The integration circuit 40 includes, for example, a resistor 41 and a capacitor 42, and smoothes the rectified voltage to a stable voltage without a pulsating flow. The output side of the integration circuit 40 is connected to the buffer circuit 50. The buffer circuit 50 is composed of, for example, an operational amplifier connected in a voltage follower type, amplifies the output voltage of the integrator circuit 40 at a predetermined magnification, and matches the output impedance to a circuit at a subsequent stage. The output side of the buffer circuit 50 is connected to the voltage comparator 60.

The voltage comparing section 60 has, for example, five comparators (CMP) 61, 62, 63, 64, 65. The voltage S50 output from the buffer circuit 50 is commonly applied to first input sides of the comparators 61 to 65. The power supply voltage VCC is divided by the resistors 66a to 66f and supplied to the second input sides of the comparators 61 to 65 as reference voltages VR1, VR2, VR3, VR4, and VR5. . These reference voltages VR1 to VR5 are set to be equal to the voltage S50 of the buffer circuit 50 corresponding to 100%, 75%, 50%, 25%, and 5 to 1% of the load current IL, respectively. I have.

When the voltage S50 applied to the first input side exceeds the reference voltages VR1 to VR5 at the second input side, the comparators 61 to 65 respectively output comparison result signals S61 to S65. The signal is output at the level "L". When the voltage S50 is equal to or lower than the reference voltages VR1 to VR5, the comparators 61 to 65 output signals S61 to S65 of the comparison result at the level "H". The output side of the voltage comparison unit 60 is connected to the display unit 70.

The display section 70 has five light emitting diodes (hereinafter, referred to as “LEDs”) 71, 72, 73, 74, 75. For example, the emission color of the LED 71 is red (R), and the emission colors of the LEDs 72 to 75 are green (G). The cathodes of the LEDs 71 to 75 are connected to the output sides of the comparators 61 to 65, respectively. The anode of the LED 71 is connected to the power supply voltage VCC via a resistor 76 a and a photocoupler 77, and the output side of the photocoupler 77 is connected to an alarm terminal 78. The cathodes of the LEDs 72 to 75 are connected to the power supply voltage VCC via resistors 76b, 76c, 76d, and 76e, respectively.

FIG. 2 is an external view of the load current detection unit of FIG. As shown in FIG. 2, the load current detection unit includes a current sensor and a display unit. The current sensor incorporates a current transformer 10 for detecting an AC magnetic field, a Hall IC (integrated circuit) for detecting a DC magnetic field, and the like. The display unit incorporates the input interface 20, the rectifier circuit 30, the integration circuit 40, the buffer circuit 50, the voltage comparison unit 60, and the display unit 70. On the surface of the display unit, red LEDs 71 indicating a 100% load and green LEDs 72 to 75 indicating a 1% to 75% load stepwise are arranged in a row.

Next, the operation of FIG. 1 will be described. When the load current IL flows through the load circuit 1 such as a distribution board, a current having a magnitude corresponding to the load current IL flows through the secondary winding 12 of the current transformer 10, and the output side of the input interface 20. Outputs a voltage corresponding to the load current IL. The voltage output from the input interface 20 is full-wave rectified by the rectifier circuit 30 and provided to the integration circuit 40.

The voltage applied to the integration circuit 40 is smoothed by the integration circuit 40, converted into a stable voltage without pulsating current, and applied to the buffer circuit 50. The voltage applied to the buffer circuit 50 is amplified by the buffer circuit 50 at a predetermined magnification (in this case, 1 ×), and as a voltage S50 corresponding to the load current IL, a low output impedance is applied to the voltage comparison unit 60 in the subsequent stage. Is output. The voltage S50 is compared with the reference voltages VR1 to VR5 by the comparators 61 to 65 of the voltage comparison unit 60, respectively.

For example, if the load current IL exceeds 100%, the voltage S50 becomes equal to or higher than the reference voltage VR1. As a result, all the signals S61 to S65 of the comparators 61 to 65 become "L", all the LEDs 71 to 75 of the display unit 70 are turned on, the output side of the photo coupler 77 is turned on, and the alarm terminal 78 is turned on. Closed.

If the load current IL is 30%, the voltage S50 has an intermediate value between the reference voltages VR3 and VR4. Accordingly, the signals S61 to S63 of the comparators 61 to 63 become "H", the signals S64 and S65 of the comparators 64 and 65 become "L", and the LEDs 74 and 75 of the display unit 70 are turned on. At this time, the output side of the photocoupler 77 is turned off, and the alarm terminal 78 is opened.

Further, when the load circuit 1 is not loaded, the voltage S50 becomes equal to or lower than the reference voltage VR5. As a result, the signals S61 to S65 of the comparators 61 to 65 all become "H", the LEDs 71 to 75 of the display unit 70 are all turned off, and the alarm terminal 78 is opened.

As described above, the load current detection unit according to the first embodiment includes the voltage comparison unit 60 that compares the voltage S50 corresponding to the load current IL with the plurality of reference voltages VR1 to VR5, and the comparison result. The display section 70 for displaying the level of the load current IL in a stepwise manner on the basis of the above is constituted by a semiconductor circuit. Thus, a small and simple load current detection unit that can be easily housed in a distribution board or the like can be obtained.

(Second Embodiment) FIG. 3 is a block diagram of a load current detection unit showing a second embodiment of the present invention. Elements common to those in FIG. 1 are denoted by common reference numerals. Have been. This load current detection unit detects a load current IL flowing through a load circuit 1 such as a DC distribution board, and performs a display corresponding to the level. The strength of a DC magnetic field generated by the load current IL is determined. It has a Hall IC 80 as a current sensor for detection.

The Hall IC 80 detects a DC magnetic field by utilizing the Hall effect, in which when a current flows through a Hall element (ie, a semiconductor) and a magnetic field perpendicular to the Hall element is applied, a voltage is generated in a direction perpendicular to the Hall element. This is an integrated circuit of the Hall element and the amplifier circuit. An input interface 20A is connected to the output side of the Hall IC 80. The input interface 20A includes, for example, resistors 21 and 22 and an operational amplifier 23, and amplifies the output voltage of the Hall IC 80 to a predetermined level.

A buffer circuit 50, a voltage comparison unit 60, and a display unit 70 similar to those in FIG. 1 are connected to the output side of the input interface 20A. In such a load current detection unit, when a DC load current IL flows through the load circuit 1 such as a distribution board, a voltage corresponding to the load current IL is output from the Hall IC 80 and supplied to the input interface 20A. . The output voltage of the Hall IC 80 is amplified to a predetermined level by the input interface 20A, and supplied to the buffer circuit 50. The subsequent operations of the buffer circuit 50, the voltage comparison unit 60, and the display unit 70 are the same as those of the load current detection unit of FIG.

As described above, since the load current detection unit according to the second embodiment has the Hall IC 80 for detecting the DC load current IL, the load current detection unit shown in FIG. The same advantages as described above can be obtained.

The present invention is not limited to the above embodiment, and various modifications are possible. For example, there are the following modifications (a) to (e). (A) The circuit configuration is not limited to those shown in FIGS. (B) The current sensor is not limited to a current transformer or a Hall IC. For example, a magnetoresistive element whose resistance changes due to magnetism can be used.

(C) The load current IL is displayed in five levels by the five LEDs 71 to 75, but the number of levels is arbitrary. (D) The display colors of the LEDs 71 to 75 are not limited to red and green. For example, yellow or orange may be used for the display color of 25% to 75%. (E) The alarm terminal 78 is closed when the load is 100% using the photocoupler 77, but the photocoupler 77 and the alarm terminal 78 are unnecessary if there is no need to output an alarm to the outside.

[0025]

[Effect of the invention]

 As described above in detail, according to the present invention, a current sensor that detects the strength of a magnetic field due to a load current and a voltage comparison that compares a voltage corresponding to the load current detected by the current sensor with a plurality of reference voltages are provided. And a display unit for displaying the level of the load current based on the comparison result. This makes it possible to configure a small and simple load current detection unit that can be easily housed in a distribution board or the like.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a load current detection unit according to a first embodiment of the present invention.

FIG. 2 is an external view of the load current detection unit of FIG.

FIG. 3 is a configuration diagram of a load current detection unit according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Load circuit 10 Current transformer 20, 20A Input interface 30 Rectifier circuit 40 Integrator circuit 50 Buffer circuit 60 Voltage comparison part 70 Display part 80 Hall IC

Claims (1)

[Utility model registration claims] A current sensor configured to detect a strength of a magnetic field generated by a load current; a voltage generator configured to generate a voltage corresponding to a level of the load current based on an output signal of the current sensor; A voltage comparing unit that compares the voltage generated in the step with a plurality of reference voltages and outputs a comparison result for each of the reference voltages; and a display unit that displays a level of the load current based on an output signal of the voltage comparing unit. And a load current detection unit.