JPH06100618B2 - Current detection system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a detection system applied to observation and monitoring of current value and overcurrent in power distribution equipment and the like.

In recent years, automation in FA (Factory Automation) relations and the construction of so-called intelligent buildings that automate building operations and maintenance relations have become popular, and along with this, we want to constantly monitor the safety issues of electrical equipment, especially the load state. The demand for is increasing by orders of magnitude.

In view of such a trend, the current detection system of the present invention needs to connect a small, lightweight, and relatively inexpensive sensor for each of a large number of distributed loads, and collect and monitor the load current states. The system is suitable for use in the following fields.

[Prior Art] Conventionally, as a means for indirectly measuring an AC load current, a method has been adopted in which a magnetic field generated by the current is captured by an instrument transformer using an iron core such as a silicon steel plate. However, there is a difficult problem in reducing the weight and size of the magnetic circuit and winding.

There is also a method of measuring the current by using a semiconductor element and magnetic circuit that utilizes the Hall effect, but there are problems in temperature characteristics and stability, and there is a resent lack of reliability.

Moreover, since these devices are basically analog devices, errors and malfunctions are likely to occur in the sensor part due to induction from the power supply to be measured, etc., and analog amplifier groups and multiplexing for multi-point input circuits are likely to occur. In the circuit, unstable factors such as interference, temperature, and secular change were associated.

[Object of the Invention] The object of the present invention is to utilize the characteristics of a magnetically sensitive pulse generator having an asymmetrical excitation effect to simplify the energization state or overcurrent value for each of a large number of electric loads distributed in a wide range. Moreover, the present invention aims to provide a new monitoring system that has a verification function that quickly and digitally detects and gives highly reliable detection data.

[Summary of the Invention] According to the current detection system of the present invention, a magnetic field is formed by a compound magnetic layer having uniaxial anisotropy in a cavity of an exciting coil for passing an AC load current to be detected. Elements, a detection coil that outputs an evoked pulse, a control coil that generates a control magnetic field, and a magnetosensitive pulse generator that is loaded by combining a bias magnet, a signal processing unit that controls and confirms the evoked pulse, and detection data and It is characterized in that it is composed of a supervisory control unit for exchanging control signals.

Then, a control magnetic field sent from the signal processing unit causes the control coil to generate a control magnetic field that repeats a gradual increase, and when a pulse is induced based on the action of this and the magnetic field generated from the exciting coil. Therefore, the AC load current value can be detected.

In addition, an induced pulse is output from the magneto-sensitive pulse generator of the current detection system only by the magnetic field generated when an overcurrent of a set value or more flows in the exciting coil that carries the AC load current, and the overcurrent detection and It has a function of performing the monitoring control.

Further, a verification current is intermittently applied to the control coil, and an induced pulse based on the generated magnetic field is treated for verification and processed, thereby verifying the operation functions of the detection system including the magneto-sensitive pulse generator as appropriate. As well as
It is also configured to discriminate between an induced pulse and a noise pulse that have detected an overcurrent.

Further, a magnetic sensing element loaded in the exciting coil,
The signal processing unit in which a magnetic-sensitive pulse generator including a detection coil, a control coil, and a bias magnet is individually provided for each of a plurality of loads, and the induced pulses and the transmission / reception of the control signal by these are integrated in at least one location. And a monitoring control unit.

In this case, the transmission path of the detection data, the control signal and the like transmitted and received between the monitoring control section and the signal processing section or other external equipment is constituted by an optical conductor to prevent induced noise and stabilize the other. It is a measure.

[Configuration and Operation of the Invention] The basic configuration and embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram illustrating the basic configuration of a current detection system according to the present invention.

That is, it shows a principle configuration in which the current detection system of the present invention is applied to wiring equipment in which loads L ₁ , L _2, etc. are respectively connected to a plurality of branch circuits of the trunk line U.

This current detection system is a magnetic-sensitive pulse generator P ₁ , P ₂ , ... P
n, an expression number processing unit Q ₁ , Q ₂ , ... Qn, and a monitoring control unit including a transmission control device T and a monitoring device W.

Magneto-sensitive pulse generators such as P ₁ and P ₂ are equipped with exemplary coils that directly carry the load current of the branch circuit. Then, based on the action of the magnetic field generated by the example coil, the dominant pulse is output by a unique principle as described later.

The signal processing units such as Q ₁ and Q ₂ have a function of sending a ramp-shaped or step-shaped control current to the control coil of the magneto-sensitive pulse generator in order to generate a control magnetic field that repeats a gradual increase.

Then, a pulse is induced based on the action of the synthetic magnetic field of the control magnetic field and the magnetic field generated by the load current.

Therefore, the load current value can be accurately determined from the control current value at the time of the induction.

The transmission control device T constituting the monitoring control unit converts each output signal of the signal processing units Q _{1 to} Qn input in parallel into a serial signal by a time division method, and transmits the serial signal to the monitoring device W configured by a computer or the like. To do.

The control signals and data transmitted from the monitoring device W to the signal processing units Q _{1 to} Qn are converted into serial signals and then transmitted to the transmission control device T through a route reverse to the above, and then converted into parallel signals. It is transmitted to Q _{1 to} Qn of the signal processing unit.

Further, in this current detection system, an induced pulse is output from the magneto-sensitive pulse generator by the generated magnetic field only when an overcurrent of a predetermined current value or more flows in an exemplary coil that directly carries a load current. The one configured as above becomes a detection system dedicated to overcurrent.

Further, a verification current is intermittently passed through the control coil, and an induced pulse based on the generated magnetic field is treated and processed for verification. By monitoring this, the operation of the entire detection system including the magnetosensitive pulse generator is performed. It is possible to verify whether is always functioning in a steady state. At the same time, whether it is a regular evoked pulse that detected overcurrent,
It is also possible to accurately determine whether it is a noise pulse.

It is possible to operate the circuit breakers B ₀ , B ₁ , B _2, etc. of the main line or the branch circuit by transmitting a cutoff signal or the like from the transmission control device T to the signal circuit Y at the time when the overcurrent is detected. is there.

[Embodiment] FIG. 2 is an external view showing a configuration of a magneto-sensitive pulse generator according to the present invention.

That is, inside the exciting coil 1 made of a spiral conductor for directly passing an AC load current, the magnetic sensitive element 3 wound with the detection coil 2 and the bias magnet 4 mounted in the vicinity thereof.
The control coil 5 wound so as to include and is loaded. 6 is an output terminal of the detection coil 2, 7 is an input terminal of the control coil 5, 8 is a movable iron piece, and 9 is a blade connection terminal.

Before describing specific examples of the present invention, properties of the magnetic sensing element 3 having special performance will be described.

As the magnetic sensitive element used in the present invention, the “magnetic sensitive element” of Japanese Patent No. 1238351 can be applied. This is a composite magnetic layer formed by applying external stress such as twist to a thin ferromagnetic wire of a magnetic alloy such as Baicalloy so as to have uniaxial magnetic anisotropy.

Alternatively, a plurality of magnetic layers having different magnetic properties such as a metal oxide and an amorphous magnetic material can be formed in a clad or a laminated shape.

The magnetically sensitive element of the composite magnetic material obtained by processing the ferromagnetic wire has a uniaxial magnetic anisotropy in the direction of the wire axis, has a portion with a relatively large coercive force near its core, and has an adjacent outer peripheral portion. The composite magnetic layer is formed to have a portion having a small coercive force.

When a detecting coil is wound around such a magnetic sensitive element and the following exciting action is applied, an extremely steep pulse is induced.

That is, the principle of pulse induction is to magnetize the entire magneto-sensitive element in advance in the positive direction (for example, to the right of the linear axis). By applying a relatively weak negative (leftward) external magnetic field to this magnetic sensitive element, only the magnetization direction of the portion of the magnetic sensitive element having a small coercive force can be shifted to the negative direction.

When an external magnetic field in the positive direction (to the right) is applied next in this state, the dislocation direction at that time is a dislocation in the same direction as the part with a large coercive force magnetized in the positive direction in advance. The dislocation rate has the unique property that it is particularly rapid.

With this rapid change in magnetic flux, an extremely steep evoked pulse is output to the detection coil.

In the present invention, the load current is to be detected from the time when the pulse induced from the magnetosensitive pulse generator is generated based on the exciting action of the AC load current.

However, in the composite magnetic body in spite Generally magnetosensitive elements, the prior history of whether has been magnetized in advance how, not necessarily constant its magnetization phenomenon.
This is an inevitable phenomenon based on the magnetic hysteresis characteristics, but some kind of correction means that keeps the previous history constant is necessary.

On the other hand, in the magneto-sensitive pulse generator used in the present invention, the bias magnet 4 to which a permanent magnet is applied acts to always magnetize the small coercive force (H _S ) portion of the magneto-sensitive element in the positive direction. There is.

Therefore, as illustrated in FIG. 3, the magnetic field that contributes to the excitation of the magnetic sensing element is a positive bias magnetic field (+ H _B ) due to the bias magnet 4 shown by the dotted line 11 and a positive or negative sign due to the AC load current shown by the dotted line of the waveform. It is a combination of symmetrical AC magnetic fields (± H _AC ).

In other words, the asymmetric magnetic field shown by the solid line waveform is generated, and the positive direction magnetic field (H _AC + H _B ) and the negative direction magnetic field (-H _AC + H _B ) are generated asymmetrically alternately.

Therefore, when the negative magnetic field (-H _AC ) due to the AC load current is larger than the bias magnetic field (+ H _B ), the negative magnetic field is: -H _AC + H _B ≥H _{S The} positive magnetic field is + H _AC + H It becomes _B. If such an asymmetrical excitation action is performed, the part of the magnetic sensitive element with a small coercive force is excited in the negative direction, and when it is displaced to the next positive direction, it is detected as shown below in the figure. A steep evoked pulse V _S is output to the coil every cycle.

In this case, since the combined exciting magnetic field in the positive direction is usually sufficiently large, the orientation magnetizing action is performed on the portion having a large coercive force, which contributes to the stabilization of the magnetized state in a self-supporting manner.

In this way, the effect of the asymmetrical excitation effect, in which a bias magnet acts on the magnetic sensing element, is extremely remarkable, and moreover, the composite magnetic layer is constantly magnetized at a constant level every time the AC load current during energization crosses the zero point. It has the special effect of correcting the condition.

Not only that, regardless of the magnitude of the load current, no matter what condition the current is rapidly cut off, the next operation is always continued exactly under the same condition regardless of the history of the magnetization state at that time, that is, the previous history. Can be made.

In the configuration of the current detection system according to the present invention described with reference to FIG. 1, an embodiment of the signal processing unit which controls the main function thereof will be described below with reference to the circuit of FIG. 4 and the time chart of FIG.

Now, by designing the load current value when the induced pulse is output to the value of the overcurrent that flows when a terminal device such as a motor or transformer fails, the overcurrent state can be determined by detecting the induced pulse. it can. However, in practice, pulsed noise may be induced from the current source to be measured or other sources and cause a malfunction.

In the present invention, a simple and highly effective circuit system is developed by focusing on the difference between the frequency components of the evoked pulse and noise and the periodicity of the evoked pulse, and the two are discriminated.

As shown in FIG. 4, the induced pulse S ₁ from the magneto-sensitive pulse generator is filtered by the bandpass filter 12 to remove noise having frequency components other than the signal, and then amplified by the amplifier circuit 13 to an appropriate voltage. Applied to 14.

As a result, the flip-flop 15 is inverted and the output is "0".
Then, the gate 14 is closed by the input of the signal S ₂ . Then, the window time setting counter 16 and the pulse number accumulating counter 17 both start to operate (the reset / count terminal of the counter is set to "1" reset and "0" count).

The counter 16 generates the gate signal S ₃ synchronized with the period of the non-measured current with reference to the timing of the pulse input first, and the evoked pulse S ₁ enters during the period of “1” of this gate signal S _3. If yes, it is determined to be valid.

The counter 17 accumulates this pulse number and compares the data D ₁ with the data set in the latch 18 in advance. When the two match, the flip-flop 20 is set by the match signal S ₄ output from the comparator 19. As a result, the signal S ₅ is output, which allows processing such as interrupts.

This data D ₁ sets how many cycles the cumulative number of evoked pulses during overcurrent detection or verification continues before outputting a signal.

Further, the counter 21 generates the timing of the time T in cooperation with the comparator 22 and the setting circuit 23, and defines the maximum number of pulses accumulated in the counter 17.

The value of this time T takes into consideration the maximum time of the count number setting value. That is, if the evoked pulse is not input during two periods of the gate signal S ₃ being “1” and time T,
It is determined that the first input pulse is noise having no periodicity. Then, the flip-flop 15 is cleared by the count end signal S ₆ relating to the time T, all the counters are stopped, the gate 14 is opened, and the initial state is returned. These states are as shown in the time chart of FIG.

The above is the measurement cycle, but at the time of verification, the verification command signal
Pulse S that passes through when S ₇ (state signal) is applied to gate 24
After K is power-amplified by the power amplifier 25, it is applied to the verification coil of the magnetosensitive pulse generator. As a result, a verification pulse is generated, and the detection operation of the entire system can be confirmed by the same path as the above-mentioned overcurrent detection.

In this way, a large discrimination ratio can be obtained with a simple circuit by separating the induced pulse from the magneto-sensitive pulse generator from BPF using its frequency characteristics and noise using its periodicity. ， In fact, it is possible to eliminate all malfunctions due to noise.

In the current detection system of the present invention, the operation of applying the verification current to the control coil 5 and recognizing the pulse generated in the detection coil 2 forms a signal loop including the magneto-sensitive pulse generator and the processing system. . Therefore, it has the advantage that the operation of the entire system as well as the magnetic sensitive pulse generator can be verified naturally.

Further, particularly when verification of the operation of the system is required, it is possible to generate a verification pulse in the detection coil 2 by applying a comparatively large intermittent pulsed verification current to the control coil 5. However, in some cases, the induced pulse due to the AC load current is superimposed and output to the detection coil, but from the timing of the verification pulse and the induced pulse,
It goes without saying that they can be easily distinguished.

[Advantages of the Invention] The current detection system of the present invention has a relatively simple configuration and can be downsized, and an arbitrary current value can be digitally measured without using an instrument transformer such as a current transformer. It has the advantage of being able to detect accurately.

Therefore, it is a system that can be applied as a current detection means in a general electric circuit including a power transmission and distribution system. Moreover, since it has a feature that a pulse is continuously generated for each cycle of the load current when the specified current value is reached, it is convenient for monitoring the load current and overcurrent of electric power equipment. In addition, the operation of this system can be easily verified, so it is especially useful for applications that require monitoring of a large number of power equipment, such as factory FA related equipment and maintenance systems for power equipment in intelligent buildings. It is suitable.

Further, the magneto-sensitive pulse generator used in the present invention is small and lightweight and can be provided at low cost. It can be easily connected to the circuits of various electrical equipment, and can be easily connected to many loads at the end of the current wiring distributed over a wide area, so it can be used as a sensor for early detection at an accident site. Expected to have utility. In such a case, a method of converting pulse signals from a large number of magneto-sensitive pulse generators into optical signals and configuring a wiring line of an optical fiber cable to perform centralized monitoring control can be economically realized. It can be used in various ways.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of the present invention, FIG. 2 is a sectional view of the structure of a magneto-sensitive pulse generator using a magneto-sensitive element, and FIG. 3 is a working magnetic field and a time of an induced pulse for explaining an asymmetric excitation effect. FIG. 4 is a circuit diagram of the signal processing unit, and FIG. 5 is a time chart for explaining the operation. Reference symbol U is a trunk line, P ₁ and P ₂ are magnetic sensitive pulse generators, L ₁ and L ₂ are loads, Q ₁ , Q ₂ and Qn are signal processing units, T is a transmission control device, W is a monitoring device, and B ₀ , B ₁ , B ₂ are circuit breakers, 1 is an excitation coil, 2 is a detection coil, 3 is a magnetic sensing element, 4 is a bias magnet, 5 is a control coil, 6 is an output terminal, 7 is an input terminal, 8 is a movable iron piece. , 9 is a blade connection terminal, 11 is a bias magnetic field, 12 is a bandpass filter, 13 is an amplifier circuit, 14, 24 is a gate, 15, 20 is a flip-flop, 16, 17, 21 is a counter, 18 is a latch, 19 , 22 is a comparator, 23 is a setting circuit, 25 is a power amplifier,

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaaki Ishizuka 4-1-1 Yushima, Bunkyo-ku, Tokyo Kanadenki Co., Ltd. (72) Inventor Akira Matsushita 2-99 Kosugi Gotencho, Nakahara-ku, Kawasaki-shi, Kanagawa Address: Japan System Research Institute Co., Ltd. (72) Inventor Katsuyoshi Nakano 2-99, Kosugi Gotencho, Nakahara-ku, Kawasaki City, Kanagawa Address: Japan System Research Institute Co., Ltd. (56) Reference JP-A-1-46658 (JP, A) Kai 63-243765 (JP, A)

Claims (6)

[Claims] 1. A magnetic sensing element having an asymmetrical excitation effect, which is composed of a composite magnetic layer having uniaxial anisotropy, and a evoked pulse are output to a cavity of an excitation coil for passing an AC load current for detection. A detection coil, a magnetic-sensitive pulse generator mounted by combining a control coil for generating a control magnetic field and a bias magnet, a signal processing unit for controlling and confirming an induced pulse, and a monitoring control unit for exchanging detection data and control signals. And a current detection system characterized by comprising 2. A pulse generated by a control current sent from the signal processing unit, wherein a control magnetic field is repeatedly generated in the control coil, and the magnetic field generated by the exciting coil is induced. The current detection system according to claim 1, wherein the AC load current can be detected from the time when 3. An overcurrent detection is performed by causing an induction pulse to be output from the magnetic sensing pulse generator only by a magnetic field generated when an overcurrent of a set value or more flows in the exciting coil for passing an AC load current. The current detection system according to claim 1, wherein the current detection system is configured to perform the monitoring control thereof. 4. A verification current is intermittently applied to the control coil, and an induced pulse based on the generated magnetic field is treated as a verification signal to be processed, whereby the operation function of the entire detection system including the magnetosensitive pulse generator is improved. The verification is performed appropriately, and it is configured to determine whether the induced pulse or the noise pulse has detected an overcurrent.
Current detection system described 5. The magneto-sensitive pulse generator comprising a magneto-sensitive element, a detection coil, a bias magnet and the like loaded in the cavity of the exciting coil is individually connected for each of a plurality of loads, and The current detection system according to claim 4, wherein the induction pulse, the control current, and the like are transmitted and received by the signal processing unit and the supervisory control unit that are integrated in at least one place. 6. A transmission path for transmitting the detection data, control signals, etc. transmitted and received between the monitoring control section and the signal processing section or other external equipment is constituted by an optical conductor. 5) Described current detection system