JP2015040799A - Power supply circuit device, curent measurement device, power monitoring system, and method for protecting power supply circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a current measurement device comprising a current measurement unit for measuring a current using a current transformer and a power supply circuit for driving the current measurement unit by using power obtained from the current transformer, the power supply circuit in the current measurement device being protected against an overvoltage generated in the current transformer.SOLUTION: A current measurement device comprises: a current measurement unit for measuring a current using a current transformer; a power supply circuit for rectifying and smoothing power generated in the current transformer to charge an electric double-layer capacitor and driving the current measurement unit by a charged voltage of the electric double-layer capacitor; an input switching circuit for selectively supplying power obtained from the current transformer to the current measurement unit or the power supply circuit; and an overvoltage detection circuit for switching the output of the input switching circuit to the current measurement unit side when, while the electric double-layer capacitor is fully charged, the voltage of the rectified and smoothed power exceeds a prescribed value.

Description

  The present invention relates to a current measuring device for measuring a current flowing in a power supply line, a power supply circuit device in the current measuring device, a power monitoring system constructed using the current measuring device, and a protection method for the power supply circuit device.

  FIG. 8 shows a schematic configuration example of the current measuring apparatus 1 that measures the current flowing through the power supply line L using a current transformer (current transformer) CT. The current measuring device 1 generally includes a current measuring unit 10 and a power supply circuit 20 that are alternatively connected to an output terminal of the current transformer CT via an input switching circuit 2. The current measuring unit 10 is interposed between the output terminals of the current transformer CT and converts a current / voltage converter 11 which converts the output current of the current transformer CT into a voltage. Provided as a detection element. Further, the current measuring unit 10 measures an amplifier 12 that amplifies an output voltage obtained through the current / voltage converter (measurement resistor) 11, and a current flowing through the power supply line L from the output voltage of the amplifier 12. And a microprocessor unit (microcomputer; MPU) 13. And the said current measurement part 10 is comprised so that the measured value of the said current calculated | required in the said MPU13 may be transmitted by radio | wireless to the high-order apparatus which is not shown in figure via the antenna 15 from the transmitter 14, for example.

  On the other hand, the power supply circuit 20 includes a rectifier circuit 21 that rectifies and smoothes the electric power obtained from the current transformer CT, and a stabilized power supply 22 that makes the output voltage of the rectifier circuit 21 constant. The power supply circuit 20 charges the electric double layer capacitor 23, which is a storage element, with the output voltage of the stabilized power supply 22, and uses the charging voltage of the electric double layer capacitor 23 as an internal power supply voltage for driving the current measuring unit 10. Is configured to output as

  Specifically, the rectifier circuit 21 in the power supply circuit 20 includes, for example, a diode bridge circuit 21a that rectifies AC power obtained from the current transformer CT as shown in FIG. 9, and a rectified output of the diode bridge circuit 21a. Is provided with a smoothing capacitor 21b. Then, the DC voltage smoothed through the smoothing capacitor 21b is applied to the stabilized power source 22 composed of, for example, a power supply regulator IC to obtain a constant stabilized DC voltage. The electric double layer capacitor 23 is charged with the stabilized DC voltage.

  Here, when the electric double layer capacitor 23 is charged to increase its charging voltage and the electric double layer capacitor 23 is fully charged, the electric power is supplied from the stabilized power source (power regulator IC) 22 to the electric double layer capacitor 23. It becomes difficult for the charging current to the multilayer capacitor 23 to flow. Then, the output voltage of the diode bridge circuit 21a that rectifies the power supplied from the current transformer CT becomes high, and a situation in which the rated voltage of the diode bridge circuit 21a and the stabilized power source 22 is exceeded occurs. The constant voltage diode 24 provided at the input portion of the stabilized power supply 22 defines the maximum value of the DC voltage applied to the stabilized power supply 22 via the diode bridge circuit 21a, whereby the current transformer It plays a role of protecting the diode bridge circuit 21a and the stabilized power source 22 from an overvoltage generated between the output terminals of the CT.

  According to the current measuring device 1 configured as described above, the power required for driving the current measuring unit 10 using the power obtained from the current transformer CT attached to the power supply line L for the purpose of current measurement. Can be generated, and this power can be self-powered to perform current measurement.

  Although different from the current measuring device 1 described above, a device that operates by self-power feeding and collects measurement data is introduced in, for example, Patent Document 1. Incidentally, the measuring device introduced in this Patent Document 1 stores power generated using a power generation system using natural energy such as a solar panel in a power storage means such as a battery, and uses the power stored in the power storage means. This eliminates the need for external power supply.

JP 2013-23857 A

  By the way, in the current measuring apparatus 1 configured as described above, the diode bridge circuit 21a and the stabilized power supply (power supply regulator IC) 22 can be protected by certainly including the constant voltage diode 24. However, when the electric double layer capacitor 23 is fully charged for a long period of time and the power supplied to the power supply circuit 20 decreases, and when the current capacity of the current transformer CT is large, the current It cannot be denied that the voltage generated between the output terminals of the current collector CT gradually increases. For this reason, a large-sized diode having a large allowable current capacity is required as the constant voltage diode 24, and measures for heat dissipation are also required. As a result, there arises a problem that the current measuring device 1 is enlarged and its manufacturing cost is increased.

  The present invention has been made in consideration of such circumstances, and the object thereof is to increase the current capacity of the constant voltage diode without increasing the current capacity of the diode bridge circuit or the stabilized power supply (power supply regulator IC) in the power supply circuit. ) Is protected from overvoltage, and a power supply circuit device, a current measuring device, a power monitoring system, and a method for protecting the power supply circuit device can be provided.

In order to achieve the above-described object, a power supply circuit device according to the present invention
A power supply circuit that charges a power storage element with a voltage of power obtained by rectifying and smoothing power generated in a current transformer attached to a power supply line, and outputs a charging voltage of the power storage element as an internal power supply voltage;
An overvoltage detection circuit for stopping power supply to the power supply circuit when the power storage element is in a fully charged state and the voltage of the rectified and smoothed power exceeds a predetermined value; It is characterized by having.

  Preferably, the power supply circuit generates, for example, a predetermined voltage by inputting a rectification circuit that rectifies and smoothes the electric power generated in a current transformer attached to a power supply line and outputs the output voltage of the rectification circuit. A stabilized power source that outputs power, a voltage that is output from the stabilized power source, a storage element that drives the electronic device by supplying the charged voltage to a predetermined electronic device, and the stabilized power source And a constant voltage diode (constant voltage element) that regulates the maximum value of the voltage.

  Incidentally, the power storage element is composed of, for example, an electric double layer capacitor. Further, the overvoltage detection circuit outputs an overvoltage detection signal, for example, to drive an input switching circuit interposed between the current transformer and the power supply circuit, thereby generating electric power generated in the current transformer. A circuit unit other than the power supply circuit is output so that power supply to the power supply circuit is stopped.

The current measuring device according to the present invention is
A current measurement unit that measures a current flowing through the power supply line from a current value detected through a current transformer attached to the power supply line to be measured;
A power supply circuit that charges a power storage element with a voltage of power obtained by rectifying and smoothing the power generated in the current transformer, and that drives the current measuring unit with a charging voltage of the power storage element;
An input switching circuit for selectively outputting the power obtained from the current transformer to the current measuring unit or the power source circuit;
An overvoltage detection circuit that switches the output of the input switching circuit to the current measuring unit when the storage element is in a fully charged state and the voltage of the rectified and smoothed power exceeds a predetermined value. It is said.

  Incidentally, the overvoltage detection circuit is configured to output an overvoltage detection signal when the voltage of the rectified and smoothed power exceeds the value of the full charge voltage of the storage element. The input switching circuit is configured to output the power obtained from the current transformer upon receipt of the overvoltage detection signal to the current measuring unit side.

  Further, the current measuring unit converts the current flowing through the current transformer using a current detection element connected to the output terminal of the current transformer via the input switching circuit, for example, a current measuring resistor. And a current flowing through the current transformer from the voltage. Preferably, the input switching circuit includes a connection element that is conductively driven when the overvoltage detection signal is input and connects an output terminal of the current transformer to a current detection element in the current measurement unit, and the connection element is connected via the connection element. The power supply to the power supply circuit is stopped using a decrease in the output terminal voltage of the current transformer by the current detection element connected to the output terminal of the current transformer.

  The current measuring device preferably further includes a display circuit that inputs the overvoltage detection signal output from the overvoltage detection circuit and presents that the storage element is in a fully charged state and is in an overvoltage state. By the way, when the current transformer is provided with a constant voltage diode for open protection, if the overvoltage detection circuit is set to detect a voltage higher than the constant voltage diode for open protection, It is also possible to notify a failure of the open-circuit protective constant voltage diode using a display circuit.

Moreover, the power monitoring system according to the present invention includes a plurality of current measuring devices having the above-described configuration that respectively measure the current flowing through each power line of a plurality of facilities to be measured,
A data collection device that periodically collects measurement values from each of these current measurement devices;
And a monitoring device that analyzes the measured values collected by each of the current measuring devices collected by the data collecting device and monitors the power usage status in the plurality of facilities by displaying the analysis result. It is said.

  Preferably, the current measuring device includes a transmitter that periodically transmits a measured value of a current flowing in a power supply line of the facility to be measured to the data collecting device, and the data collecting device includes the plurality of the data collecting devices. The measurement values transmitted from the current measuring devices are stored in association with the current measuring devices, and are used for analysis by the monitoring device. At this time, each of the current measurement devices preferably transmits the overvoltage detection signal detected by the overvoltage detection circuit to the data collection device together with the measurement value obtained by the current measurement unit.

The power circuit device protection method according to the present invention includes a rectifier circuit that rectifies and smoothes electric power generated in a current transformer attached to a power line, and outputs the rectifier circuit. A stabilized power source that generates and outputs a voltage, a storage element that is charged by a predetermined voltage output from the stabilized power source, supplies the charged voltage to a predetermined electronic device, and drives the electronic device, and the stabilization In a method for protecting a power supply circuit device comprising a constant voltage element that regulates the maximum value of a voltage input to a power supply,
When the storage element is fully charged and the output voltage of the rectifier circuit has reached a value higher than the voltage value defined by the constant voltage element, the power generated in the current transformer is supplied to the power source. The power supply to the rectifier circuit is stopped by outputting to a circuit unit other than the circuit.

  According to the power supply circuit device, the current measuring device, and the power supply circuit device protection method configured as described above, for example, a power storage element made of an electric double layer capacitor is in a fully charged state and rectifies AC power obtained from a current transformer When the output voltage of the rectifier circuit is an overvoltage, the output of the power obtained from the current transformer to the power supply circuit is stopped, so that the power supply circuit can be effectively protected from the overvoltage. In addition, the occurrence of the overvoltage itself can be suppressed without increasing the current capacity of the constant voltage element provided in the power supply circuit and without taking any special heat dissipation measures for the constant voltage element. Therefore, the power supply circuit device and the current measuring device can be realized in a compact and inexpensive manner.

  Further, according to the power monitoring system having the above configuration, the measured values of the currents flowing through the power supply lines of the plurality of facilities to be measured are easily and effectively collected, and the measured values are analyzed to analyze the plurality of facilities. It is possible to efficiently monitor the amount of power used and to understand the situation. In addition, since each of the current measuring devices operates by self-power feeding, the configuration of the entire system including the power supply system can be simplified. Therefore, its practical advantage is great.

The principal part schematic block diagram of the electric current measurement apparatus which concerns on one Embodiment of this invention. The figure which shows the structural example of the power supply circuit and overvoltage detection circuit in the current measuring device shown in FIG. FIG. 3 is a waveform diagram showing operations of the power supply circuit and the overvoltage detection circuit shown in FIG. 2. The principal part schematic block diagram of the electric current measurement apparatus which concerns on another embodiment of this invention. The figure which shows the structural example of the input switching circuit and its peripheral circuit in the current measuring device shown in FIG. The figure which shows schematic structure of the electric power monitoring system constructed | assembled using the electric current measurement apparatus shown in FIG. The figure which shows the data collection timing in the electric power monitoring system shown in FIG. The principal part schematic block diagram which shows an example of the conventional electric current measuring apparatus. The figure which shows the structural example of the power supply circuit in the current measuring device shown in FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a main part of a current measuring apparatus 1 according to an embodiment of the present invention. The same parts as those of the conventional current measuring apparatus 1 shown in FIG. The current measuring device 1 according to the present invention is characterized in that a DC voltage applied to the stabilized power supply (power supply regulator IC) 22 in the power supply circuit 20 is monitored, and the electric double layer capacitor 23 as a storage element is provided. An overvoltage detection circuit 25 is provided that outputs an overvoltage detection signal when the battery is fully charged and the DC voltage output from the rectifier circuit 21 exceeds a predetermined value. Then, the overvoltage detection signal output from the overvoltage detection circuit 25 is given to the input switching circuit 2 to switch the output of the input switching circuit 2 to the current measuring unit 10 side, thereby causing the current transformer CT. The power supply to the power supply circuit 20 is stopped.

  The overvoltage detection signal is also given to the microprocessor unit (microcomputer; MPU) 13. The overvoltage detection signal is logically ORed with an input switching signal output from the MPU 13 via, for example, a wired OR circuit 26 and supplied to the input switching circuit 2. Therefore, the input switching circuit 2 replaces the power generated in the current transformer CT with the power supply circuit 20 when the input switching signal is given and when the overvoltage detection signal is given. This is output to the current / voltage converter 11 in the unit 10.

  FIG. 2 shows a configuration example of the power supply circuit 20 constructed with the overvoltage detection circuit 25. The power supply circuit 20 basically includes a rectifier circuit 21 comprising a diode bridge circuit 21a and a smoothing capacitor 21b for rectifying and smoothing the electric power generated in the current transformer CT as shown in FIG. Prepare. Further, the power supply circuit 20 includes a stabilized power supply 22 including a power supply regulator IC that inputs the output voltage of the rectifier circuit 21 and generates and outputs a constant voltage. Then, the electric double layer capacitor 23 is charged with a constant voltage output from the stabilized power source 22, and the current measuring unit 10 is driven by feeding the charging voltage of the electric double layer capacitor 23 to the current measuring unit 10. Composed.

  Further, the power supply circuit 20 is provided at the input portion of the stabilized power supply 22 and defines the maximum value of the DC voltage applied to the stabilized power supply 22, thereby generating between the output terminals of the current transformer CT. A constant voltage diode 24 is provided to protect the diode bridge circuit 21a and the stabilized power source 22 from an overvoltage. The overvoltage detection circuit 25 detects an overvoltage detection resistor 25a connected in series to the anode of the constant voltage diode 24 and a voltage generated in the overvoltage detection resistor 25a due to a current flowing through the constant voltage diode 24. And a transistor 25b that is turned on / off.

  Incidentally, the transistor 25b has an emitter grounded, a collector connected to the voltage output line of the stabilized power supply 22 via a load resistor (pull-up resistor) 25c, and a voltage generated in the overvoltage detection resistor 25a at the base. A grounded-emitter voltage detection circuit that performs an input and inversion operation is configured. In FIG. 2, 25d is a base current limiting resistor interposed between the base of the transistor 25b and the overvoltage detecting resistor 25a, and 25e is connected in parallel between the base and emitter of the transistor 25b. This is a resistor for guaranteeing base voltage. The capacitor 25f connected in parallel between the collector and emitter of the transistor 25b plays a role of giving a predetermined time constant to a change in the output voltage (collector voltage) of the transistor 25b.

  Here, the basic operation of the power supply circuit 20 configured as described above will be described with reference to FIG. 3. In the power supply circuit 20, the power generated in the current transformer CT is shown in FIG. Enter as shown. As is well known, this AC power is proportional to the AC current I1 flowing through the power line L (primary side of the current transformer CT), that is, the secondary side of the current transformer CT, that is, the current of the current transformer CT. It is the electric power given by the alternating current I2 generated between the output terminals.

  Then, when the power supply circuit 20 is started up, the AC power generated between the output terminals of the current transformer CT is rectified through the diode bridge circuit 21a and smoothed by the smoothing capacitor 21b. The output voltage gradually increases as shown in FIG. As a result, the stabilized power supply (power regulator IC) 22 operates by receiving the output voltage of the rectifier circuit 21, and the electric double layer capacitor 23 is charged by receiving the stabilized output voltage of the stabilized power supply 22. Is done. Then, after a predetermined time has elapsed from the start of the power supply circuit 20 (timing t1), the electric double layer capacitor 23 reaches a fully charged state by the above charging.

  Thereafter, when power supply from the current transformer CT continues in a state where the electric double layer capacitor 23 reaches a fully charged state, the stabilized power source 22 supplies the electric double layer capacitor 23 in a fully charged state. Since the output current decreases, the input voltage of the stabilized power supply 22, that is, the output voltage of the rectifier circuit 21 increases accordingly. When the output voltage of the rectifier circuit 21 exceeds the breakdown voltage (for example, 6 V) of the constant voltage diode 24, a current starts to flow through the constant voltage diode 24. As a result, a voltage as shown in FIG. 3D is generated in the overvoltage detection resistor 25a by the current flowing through the overvoltage detection resistor 25a connected in series to the constant voltage diode 24. Incidentally, as the overvoltage detection resistor 25a, for example, a resistance of about 100Ω is used.

  That is, when the electric double layer capacitor 23 is fully charged and the output voltage of the rectifier circuit 21 rises to an overvoltage upon receiving power supply from the current transformer CT, the constant voltage diode is accordingly generated. Current begins to flow through 24. A voltage is generated across the overvoltage detection resistor 25a by the current flowing through the constant voltage diode 24. Further, as the output voltage of the rectifier circuit 21 further increases, the current further increases through the constant voltage diode 24, whereby the voltage generated between both ends of the overvoltage detection resistor 25a is shown in FIG. ) As shown.

  Then, a voltage generated between both ends of the overvoltage detection resistor 25a is received, and the transistor 25b is turned on as shown at a timing t3 in FIG. 3, and the collector voltage of the transistor 25b is rapidly lowered to the ground potential. Thereafter, the capacitor 25f connected in parallel between the collector and emitter of the transistor 25b is charged through the load resistor 25c, so that the collector voltage of the transistor 25b gradually increases. The rising speed of the collector voltage of the transistor 25b is defined by a time constant defined by the capacitance of the capacitor 25f and the resistance value of the load resistor 25c.

  The collector voltage of the transistor 25b operating in this way is output as an overvoltage detection signal. Then, this overvoltage detection signal is given to the input switching circuit 2, and the input from the current transformer CT is switched by switching the output of the input switching circuit 2 to the current measuring unit 10 side as shown in FIG. The supplied power to the power supply circuit 20 is stopped. The supply of power to the power supply circuit 20 is stopped during a period until the collector voltage of the transistor 25b reaches the original voltage level, that is, the output voltage of the electric double layer capacitor 23, and the overvoltage detection signal disappears. Done.

  Then, when the overvoltage detection signal disappears as shown at timing t4 in FIG. 3, the forced switching control for the input switching circuit 2 by the overvoltage detection signal ends, and accordingly, the input switching circuit 2 The electric power input from the fluency CT is supplied to the power supply circuit 20 again. The overvoltage detection circuit 25 outputs the overvoltage detection signal via the input switching circuit 2 every time the above-described overvoltage is detected with the supply of power from the current transformer CT to the power supply circuit 20. The power supply to the power supply circuit 20 is prohibited.

  During the period in which power supply to the power supply circuit 20 is prohibited, the power generated in the current transformer CT is converted into a current / voltage converter (in the current measuring unit 10) via the input switching circuit 2. Measurement resistance) 11. The power supplied from the current transformer CT is converted into a voltage corresponding to the current flowing through the power line L in the current / voltage converter (measurement resistor) 11. However, whether or not to detect the voltage required in the current / voltage converter 11 in this way is left to the current measuring unit 10. Incidentally, in the current measuring unit 10, the input switching circuit 2 is controlled to be switched from the voltage generated in the current / voltage converter 11 under the above-described cycle independently of the above-described overvoltage detection signal. Perform measurement. Therefore, the switching control of the input switching circuit 2 based on the overvoltage detection signal is executed for the purpose of protecting the power supply circuit 20.

  Incidentally, the response time until the voltage generated across the overvoltage detection resistor 25a rises due to the conduction of the constant voltage diode 24 and reaches the on-operation threshold voltage of the transistor 25b is set to about 1 ms, for example. . The time (time constant) until the collector voltage of the transistor 25b returns to the internal power supply voltage by charging the capacitor 25f through the load resistor 25c after the transistor 25b is turned on is set to about 10 ms, for example. The Therefore, in this case, the charging of the electric double layer capacitor 23 by the stabilized power source 22 is repeated 1 ms after a rest period of 10 ms.

  However, in order to prevent the function of the current measuring unit 10 from being impaired by such intermittent charging of the electric double layer capacitor 23, the current measuring unit 10 wakes up, for example, every 3 seconds. The power consumption is suppressed by operating for 0.5 seconds and resting during other periods. Also, the transmission processing of measurement data and the like via the transmitter 14 is performed only once per minute, for example, so that the power consumption is suppressed. As a result, the voltage stored in the electric double layer capacitor 23 is maintained substantially constant over the operation period of the current measuring device 1 even by the intermittent operation of the current measuring unit 10 described above. It has become.

  Thus, according to the power supply circuit 20 configured as described above, the electric double layer capacitor 23 is in a fully charged state, and in this fully charged state, the output voltage of the rectifier circuit 21 is equal to the breakdown voltage of the constant voltage diode 24. Whenever it exceeds, the overvoltage detection circuit 25 detects the overvoltage state. Then, the input switching circuit 2 is controlled using an overvoltage detection signal output from the overvoltage detection circuit 25, whereby the input switching circuit 2 transmits the power of the current transformer CT from the power supply circuit 20 to the current measuring unit 10. It is to change to the side.

  Therefore, an excessive increase in the current flowing through the constant voltage diode 24 due to a rise in voltage caused by the electric double layer capacitor 23 being fully charged is effectively suppressed. As a result, the current capacity required for the constant voltage diode 24 can be reduced, and power consumption in the constant voltage diode 24 can be suppressed. Therefore, it is not necessary to use the constant voltage diode 24 having a large current capacity, and no special heat radiation countermeasure for the constant voltage diode 24 is required.

  In addition, the current measuring unit 10 determines the occurrence of overvoltage generated at the output terminal of the current transformer CT as the current decreases due to the full charge of the electric double layer capacitor 23, and the current output from the current transformer CT. The current / voltage converter (measurement resistor) 11 in FIG. In particular, the output voltage of the rectifier circuit 21 is monitored in the overvoltage detection circuit 25, and the above-described control is executed simply by controlling the input switching circuit 2 with the overvoltage detection signal output from the overvoltage detection circuit 25. It becomes possible. Accordingly, the current capacity required for the constant voltage diode 24 can be reduced and the size thereof can be reduced only by providing the overvoltage detection circuit 25 described above. Therefore, unintended power consumption in the power supply circuit 20 can be suppressed, and the power supply circuit 20 itself can be reduced in size and power consumption, and the current measuring device 1 can be reduced in size.

  Although the power supply circuit 20 incorporated in the current measuring device 1 has been described here, the power supply circuit device described above also generates and supplies internal power supply voltages to various electronic circuits from the power obtained from the current transformer CT. The same technique can be applied as well. In this case, for example, when an overvoltage is detected in the overvoltage detection circuit 25, the power obtained from the current transformer CT is output to the dummy resistor or the like other than the power supply circuit 20 via the input switching circuit 2. You should do it.

  In the above-described embodiment, the overvoltage detection signal output from the overvoltage detection circuit 25 and the input switching signal output from the MPU 13 in synchronization with the current measurement operation are input to the input switching circuit via the wired OR circuit 26. 2 to give. However, for example, as shown in FIG. 4, the overvoltage detection signal and the input switching signal may be separately supplied to the input switching circuit 2. In such a configuration, it is also useful to provide a display circuit 27 for displaying, for example, when the overvoltage detection signal is output.

  FIG. 5 shows a configuration example of the display circuit 27, the input switching circuit 2, and its peripheral circuits. As shown in FIG. 5, the display circuit 27 includes a light emitting diode (LED) 27b in which a current limiting resistor 27a is connected in series. The internal power supply voltage Vcc output from the electric double layer capacitor 23 is received through the transistor (FET) 27c which is turned on upon receiving the overvoltage detection signal, and is driven to emit light (light on). That is, the display circuit 27 drives and drives the light emitting diode (LED) 27b over a period during which the overvoltage detection signal is output.

  On the other hand, the input switching circuit 2 includes two photo MOS relays 31 and 32 that are turned on in response to the overvoltage detection signal or the input switching signal. The current / voltage converter (measurement resistor) 11 is connected between the photo MOS relays 31 and 32 and is connected between the output terminals of the current transformer CT via the photo MOS relays 31 and 32. . Incidentally, each of the photo MOS relays 31 and 32 includes MOS-FETs 33 and 34 and MOS-FETs 35 and 36 connected in series forming a switch element between a pair of terminals, respectively. The MOS-FETs 33 and 34 and the MOS-FETs 35 and 36 are light emitting diodes 37 that are driven to emit light in response to the overvoltage detection signal or the input switching signal applied to the control terminals of the photo MOS relays 31 and 32, respectively. Each of them is turned on in response to light from 38.

  The current / voltage converter (measurement resistor) 11 is connected to the current transformer CT when the photo MOS relays 31 and 32 constituting the input switching circuit 2 are turned on. Then, the voltage generated between the output terminals of the current transformer CT can be suppressed by outputting the electric power generated in the current transformer CT to the current / voltage converter 11 via the input switching circuit 2. Thus, the power supply to the power supply circuit 20 via the diode bridge circuit 21a is stopped.

  Incidentally, the measuring resistor (current detection element) constituting the current / voltage converter 11 has a resistance value of, for example, about 5Ω, and is 0.5 V when the output current from the current transformer CT is 100 mA. The voltage of On the other hand, the charging voltage of the smoothing capacitor 21b when the electric double layer capacitor 23 is fully charged is approximately 5V. Therefore, when the current obtained from the current transformer CT is output to the current / voltage converter 11, the output terminal voltage of the current transformer CT becomes a voltage generated in the current / voltage converter 11. The bridge circuit 21a is reverse biased. As a result, feeding of the power obtained from the current transformer CT to the power supply circuit 20 is prevented.

  As described above, when the output of the current obtained from the current transformer CT to the current / voltage converter 11 is stopped with the disappearance of the overvoltage detection signal, the output terminal of the current transformer CT is thereby stopped. The voltage rises. Then, power supply to the power supply circuit 20 is resumed via the diode bridge circuit 21a. Thereafter, such a switching operation of the input switching circuit 2 is repeated in accordance with a change in voltage applied to the stabilized power source 22.

  Further, the overvoltage detection signal for controlling the operation of the input switching circuit 2 in this way is over a certain period (for example, 1 ms) each time the voltage applied to the stabilized power supply 22 exceeds the breakdown voltage of the constant voltage diode 24. Is output. As a result, the light emitting diode 27b constituting the display circuit 27 is driven to be lit for 1 ms every 10 ms, for example. Then, the electric double layer capacitor 23 is fully charged from the blinking state of the light emitting diode 27b, visually the lighting state of the light emitting diode 27b, and accordingly, the voltage applied to the stabilized power source 22 is the constant voltage. It is presented that there is a high voltage condition that can exceed the breakdown voltage of the diode 24. In general, it is suggested that the electric double layer capacitor 23 is fully charged.

  When the current transformer CT is provided with a constant voltage diode ZD for open protection as shown in FIG. 5, the breakdown voltage of the constant voltage diode 24 is determined as the operation of the constant voltage diode ZD for open protection. It is desirable to set it slightly higher than the voltage. If such an operating condition is set, a current flows through the constant voltage diode 24 even though the current transformer CT is provided with a constant voltage diode ZD for open protection, and the overvoltage detection signal is detected. Can be grasped. In other words, it is possible to know from the lighting of the light emitting diode 27b that the constant voltage diode ZD for open circuit protection has failed and as a result, the overvoltage detection signal is output.

  FIG. 6 shows a schematic configuration of a power monitoring system 100 constructed by using a plurality of current measuring devices 1 configured as described above. This power monitoring system 100 monitors the power consumption of each of a plurality of processing facilities 51, 52, 53 and an inspection facility 54 provided in order along a product processing line in a factory, for example. The plurality of current measuring devices 1 (1a, 1b to 1n) are equipped with the current transformers CT in the power supply lines of the processing facilities 51, 52, 53 and the inspection facility 54, respectively. It is provided to measure the amount of electric power supplied to each of the processing equipment 51, 52, 53 and the inspection equipment 54 via the machine CT.

  Each of the current measuring devices 1 (1a, 1b to 1n) directs current values (measured values) measured at predetermined intervals from the transmitter 14 to the higher-order receiver 61 via the antenna 15. Wirelessly transmit periodically. This wireless transmission uses, for example, a specific low power wireless communication of 920 MHz · 10 mW, for example, at a rate of once per minute and between the plurality of current measuring devices 1 (1a, 1b to 1n). It is performed periodically in different ways.

  In the host system, information sent from each of the current measuring devices 1 (1a, 1b to 1n) via the receiver 61 is converted into a data collecting device (a personal computer for data collection; PC) 62. Is stored in association with each current measuring device 1 (1a, 1b to 1n) together with the collection time information. At this time, when flag information indicating the operation state such as the overvoltage detection signal described above is sent from the current measuring device 1 (1a, 1b to 1n), the monitoring device (personal computer for monitoring; PC) 63 Then, the information collected in the data collection device 62 is analyzed by statistical processing or the like, and the analysis result is analyzed by using, for example, the energy usage 64 and the energy cost 65 in the processing equipment 51, 52, 53 and the inspection equipment 54. , Graphed and displayed as management data such as energy unit price 66.

  According to the power monitoring system 100 constructed in this way, it is only necessary to attach the current transformer CT to the power supply lines of the processing equipments 51, 52, 53 and the inspection equipment 54, so that they are monitored. There is almost no construction burden on the equipment. Further, as described above, each of the current measuring devices 1 (1a, 1b to 1n) operates by self-power feeding and executes current measurement, and therefore, a power feeding line for these current measuring devices 1 (1a, 1b to 1n). No laying is required. Moreover, each of the current measuring devices 1 (1a, 1b to 1n) includes the overvoltage detection circuit 25 as described above, and easily and effectively protects the power supply circuit 20 from the overvoltage generated in the current transformer CT. Therefore, the configuration of the current measuring device 1 (1a, 1b to 1n) can be reduced in size and simplified. Therefore, it is easy to install the current measuring devices 1 (1a, 1b to 1n), and there is no need to be troubled by securing the installation space and measures for heat dissipation.

  In addition, the current collecting device 62 (the current collecting device 1 (1a, 1b to 1n) and the receiver 61 only need to transmit data periodically by wireless communication). Measurement data in 1a, 1b to 1n) can be efficiently collected. Since the collected measurement data can be analyzed by the monitoring device 63 and the analysis result can be presented, each power of the plurality of processing facilities 51, 52, 53 and the inspection facility 54 constructing the product processing line The consumption amount can be grasped easily and efficiently. Therefore, the system cost can be minimized and its practical advantages are great.

  FIG. 7 shows the operation timing in the power monitoring system 100 described above, and each of the current measuring devices 1 (1a, 1b to 1n) has a predetermined cycle T1 (for example, 1 minute) as shown in FIG. Measurement data is transmitted to the receiver 61 every time. As shown in FIG. 7B, the MPU 13 in each of the current measuring devices 1 that obtains measurement data operates by wake-up every predetermined period T2 (for example, 3 seconds), and pauses during other periods. Therefore, the power consumption is suppressed as much as possible.

  The MPU 13 operates for a predetermined period T3 (for example, 0.5 seconds) as shown in FIG. 7C, and at a specific operation timing in the period T1, as shown in FIG. 7D. Current measurement is repeatedly performed 20 times every cycle T4 (for example, 0.1 second). The MPU 13 is configured to obtain an average value of currents repeatedly measured, for example, 20 times, and transmit the average current value toward the receiver 61 as shown in FIG. As described above, each of the current measuring devices 1 (1a, 1b to 1n) operates independently of the protection operation by the overvoltage detection circuit 25 in the power supply circuit 20 to measure the current to be measured, and the measurement data (Average current value) is obtained.

  The data collection device 62 stores the current values measured by the current measuring devices 1 (1a, 1b to 1n) for each of the current measuring devices 1 (1a, 1b to 1n). At this time, the data collection device 62 also stores flag information indicating the generation status of the overvoltage detection signal indicating the operating state of each of the current measuring devices 1 (1a, 1b to 1n). After that, the measurement data collected by the data collection device 62 is aggregated and analyzed by the monitoring device 63, thereby monitoring the power usage status in the product processing line as described above.

  The present invention is not limited to the embodiment described above. For example, the internal power supply voltage Vcc generated in the power supply circuit 20, that is, the charging voltage of the electric double layer capacitor 23 may be set according to the specification of the current measuring unit 10, and is set to 5 V, for example. In this case, it is sufficient to set the breakdown voltage of the constant voltage diode 24 for detecting the overvoltage to, for example, about 6V. Further, as described above, the operation of the input switching circuit 2 is controlled by using the overvoltage detection signal, thereby stopping the power supply to the power supply circuit 20 at the time of overvoltage, so that the current capacity of the constant voltage diode 24 is 100 mA. A degree is sufficient.

  In addition, circuit constants and the like of each part may be appropriately determined according to the specifications of the current transformer CT and the specifications required for the current measuring device 1. Further, a secondary battery such as a lithium ion battery may be used in place of the electric double layer capacitor 23. In short, the present invention can be implemented with various modifications without departing from the spirit of the present invention.

CT current transformer (current transformer)
ZD Open-circuit protection constant voltage diode L Power supply line 1 (1a, 1b to 1n) Current measuring device 2 Input switching circuit 10 Current measuring unit 11 Current / voltage converter (resistance for measurement)
12 Amplifier 13 Microprocessor unit (microcomputer; MPU)
14 Transmitter 15 Antenna 20 Power Supply Circuit 21 Rectifier Circuit 21a Diode Bridge Circuit 21b Smoothing Capacitor 22 Stabilized Power Supply (Power Supply Regulator IC)
23 Electric double layer capacitor (storage element)
24 constant voltage diode (constant voltage element)
25 Overvoltage detection circuit 25a Overvoltage detection resistance 25b Transistor 25c Load resistance (pull-up resistance)
25d Base current limiting resistor 25e Base voltage guarantee resistor 25f Capacitor 27 Display circuit 27a Current limiting resistor 27b Light emitting diode 27c Transistor (FET)
31,32 Photo MOS relay 33,34,35,36 MOS-FET
37,38 Light emitting diode 61 Receiver 62 Data collection device (personal computer for data collection; PC)
63 Monitoring device (personal computer for monitoring; PC)

Claims (11)

A power supply circuit that charges a power storage element with a voltage of power obtained by rectifying and smoothing power generated in a current transformer attached to a power supply line, and outputs a charging voltage of the power storage element as an internal power supply voltage;
An overvoltage detection circuit for stopping power supply to the power supply circuit when the power storage element is in a fully charged state and the voltage of the rectified and smoothed power exceeds a predetermined value; A power supply circuit device comprising:   The overvoltage detection circuit drives an input switching circuit interposed between the current transformer and the power supply circuit to output power generated in the current transformer to a circuit unit other than the power supply circuit. The power supply circuit device according to claim 1. A current measurement unit that measures a current flowing through the power supply line from a current value detected through a current transformer attached to the power supply line to be measured;
A power supply circuit that charges a power storage element with a voltage of power obtained by rectifying and smoothing the power generated in the current transformer, and that drives the current measuring unit with a charging voltage of the power storage element;
An input switching circuit for selectively outputting the power obtained from the current transformer to the current measuring unit or the power supply circuit;
An overvoltage detection circuit that switches the output of the input switching circuit to the current measuring unit when the storage element is in a fully charged state and the voltage of the rectified and smoothed power exceeds a predetermined value. A current measuring device. The overvoltage detection circuit outputs an overvoltage detection signal when the voltage value of the rectified and smoothed power exceeds the value of the full charge voltage of the storage element,
The current measuring device according to claim 3, wherein the input switching circuit outputs the electric power obtained from the current transformer upon receiving the overvoltage detection signal to the current measuring unit side.   The current measuring unit converts a current flowing through the current transformer using a current detection element connected to the output of the current transformer via the input switching circuit, and flows from the voltage to the current transformer. The current measuring device according to claim 3, wherein the current is detected.   The input switching circuit includes a connection element that is conductively driven when the overvoltage detection signal is input and connects an output of the current transformer to a current detection element of the current measuring unit, and the current transformer is connected via the connection element. 4. The current measuring device according to claim 3, wherein power supply to the power supply circuit is stopped using a decrease in the output voltage of the current transformer by the current detection element connected to the output of the current transformer. In the current measuring device according to claim 3,
The current measuring device further includes a display circuit that inputs the overvoltage detection signal output from the overvoltage detection circuit and presents that the storage element is in a fully charged state. A plurality of current measuring devices according to any one of claims 3 to 7, each measuring a current flowing through each power line of a plurality of facilities to be measured,
A data collection device that periodically collects measurement values from each of these current measurement devices;
A power monitoring system, comprising: a monitoring device that analyzes measurement values collected by the current measuring devices collected by the data collecting device and outputs the analysis results. The current measuring device includes a transmitter that periodically transmits a measured value of a current flowing in a power line of the facility to be measured to the data collecting device,
The power according to claim 8, wherein the data collection device stores the measurement values transmitted from the plurality of current measurement devices in association with the current measurement devices and provides them for analysis by the monitoring device. Monitoring system.   The power monitoring system according to claim 8, wherein the current measurement device transmits the overvoltage detection signal detected by the overvoltage detection circuit to the data collection device together with a measurement value obtained by the current measurement unit. A rectifier circuit that rectifies and smoothes the electric power generated in the current transformer attached to the power supply line, outputs the rectifier circuit output voltage and outputs a predetermined voltage, and the stabilized power supply. Is charged with a predetermined voltage output from the battery, and the storage device drives the electronic device by supplying the charged voltage to the predetermined electronic device, and the constant voltage device that defines the maximum value of the voltage input to the stabilized power source, In a method for protecting a power supply circuit device comprising:
When the storage element is fully charged and the output voltage of the rectifier circuit has reached a value higher than the voltage value defined by the constant voltage element, the power generated in the current transformer is supplied to the power source. A method for protecting a power supply circuit device, comprising: outputting to a circuit unit other than a circuit and stopping power supply to the rectifier circuit.

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