JPH1183913A - Electronic system watthour meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic system watthour meter wherein countermeasure making large current flow with a battery is unnecessary. SOLUTION: A service interruption detecting circuit 10 outputs a service interruption signal to a control part 3 when an AC power source interrups service, before a service interruption compensating power source circuit 5 changes the AC power source to a power source of a battery 4. The control part 3 changes high speed reference clock from a high speed reference clock generating circuit 12 to low speed reference clock from a low speed reference clock generating circuit 13 with the service interruption signal, and stops the output of an electric energy oscillating pulse circuit 7, the output of a limited period oscillating pulse circuit 8, and the function of a transmitting circuit 9. As a result, it is made unnecessary to instantaneously apply a large current with the battery 4, as in the conventional manner, when switched to a power source of the battery 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic watt-hour meter, and more particularly, to an improvement of a power failure compensating power supply when a power failure occurs in a meter.

[0002]

2. Description of the Related Art A conventional electronic watt-hour meter is constructed as shown in FIG. That is, in FIG. 7, reference numeral 1 denotes a power supply circuit that converts AC from an AC power supply to DC and supplies DC power to a circuit of an instrument, and 2 denotes a power calculation circuit that outputs a pulse having a frequency proportional to the measured power of the instrument. , And is operated by the power supply of the power supply circuit 1. Reference numeral 3 denotes a control unit for integrating the pulses from the power calculation circuit 2 to obtain the power amount, and also controls the power amount display unit 6. Since the control unit 3 needs to hold a weighing value or the like even when a power failure occurs, the power supply of the power supply circuit 1 is normally supplied, and the power supply is switched to the power supply of the battery 4 in the event of a power failure.
Operating on the power supply. Note that the power failure compensation power supply circuit 5 is configured by an OR circuit composed of a diode as shown in the figure, for example.

A power transmitting pulse output circuit 7 outputs a power transmitting pulse having a frequency proportional to power for use in power management, error testing, and the like. Reference numeral 8 denotes a time transmission pulse output circuit, which outputs a time transmission pulse synchronized with this time to an instrument having a function of measuring time.
An operation of outputting one pulse every minute is performed.

[0004] Reference numeral 9 denotes a transmission circuit for transmitting a signal such as an automatic meter reading, which outputs a transmission signal or outputs a signal to a switch for receiving the signal.
The control unit 3 also controls the power transmission pulse output circuit 7, the timed transmission pulse output circuit 8, and the transmission circuit 9.

The control unit 3 operates based on the high-speed reference clock from the high-speed reference clock generation circuit 12 when the meter is measuring the amount of electric power at the time of energization. In order to reduce the contents to be processed in step 3 and to reduce the consumption of the battery 4, the apparatus operates with a low-speed reference clock from the low-speed reference clock generation circuit 13 which consumes low current.

Conventionally, the control unit 3 detects a power failure of an instrument by a decrease in the voltage level of the power supply circuit 1 from the AC power supply (for example, 6 V is reduced to 3 V), and switches the reference clock or transmits a power amount transmission pulse. Control, the timed transmission pulse was stopped, and the transmission process was stopped.
Is switched from the power supply circuit 1 to the power supply of the battery 4, and then the power failure processing is performed. Therefore, the battery 4 needs to be able to instantaneously supply the same current as the current consumption when energized. For this reason, it is necessary to take measures such as the type of the battery and a use method that does not increase the internal resistance.

[0007]

Conventionally, as described above, it is necessary to take measures for the type of the battery and the method of use in order to flow a large current as described above. There is. In the case of the electronic watt-hour meter, if the voltage drops and the control unit 3 malfunctions, a fatal problem such as disappearance of the measured value occurs. Therefore, a high-performance battery is used. To reduce the increase in the internal resistance of the battery.

[0008] However, there is a problem that the measures are not versatile, for example, the characteristics of the internal resistance change only by changing the capacity of the battery. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide an electronic watt-hour meter that does not require a measure for causing a large current to flow through a battery during a power failure.

[0009]

An electronic watt-hour meter according to the present invention comprises: a power supply circuit for converting an AC power supply to a DC power supply; a power failure compensation power supply circuit for switching to a battery power supply when the AC power supply fails; A power calculation circuit that outputs a pulse with a frequency proportional to the measured power of the instrument, a control unit that operates on the power failure compensation circuit power supply and integrates the pulses of the power calculation circuit to determine the amount of power, and a power failure when the AC power supply fails A power failure detection circuit that detects a power failure and outputs a power failure signal before the compensation power supply circuit switches to the battery power source; and a control unit that controls an operation of the control unit based on the power failure signal output from the power failure detection circuit. Features.

With this configuration, before the power supply of the control unit is switched to the power supply from the battery, the power failure detection circuit detects the power failure and shifts to the power failure processing to reduce the current consumption of the circuit. In addition, it is possible to eliminate an instantaneous flow of a large current through the battery, and to provide an electronic watt-hour meter that does not require any measures for flowing a large current through the battery.

Here, the control means switches the reference clock of the control unit from the normally used reference clock of the first speed to the reference clock of the second speed lower than the first speed in response to the power failure signal. It may have switching means.

By switching to a low-speed reference clock with such a configuration, current consumption can be reduced. Further, the switching means may be provided outside the control unit.

Further, in the case of an electronic watt-hour meter having an electric energy transmission pulse output circuit for outputting an electric energy transmission pulse having a frequency proportional to the electric power, the electric energy transmission pulse output from the electric energy transmission pulse output circuit is output from the electric energy transmission pulse output circuit. Means may be provided for stopping output by a power failure signal.

Further, in the case of an electronic watt-hour meter having a timed transmission pulse output circuit for outputting a timed transmission pulse synchronized with the time to an instrument having a function of measuring time, the time is output from the timed transmission pulse output circuit. A means for stopping the output of the timed transmission pulse by the power failure signal may be provided.

Further, in the case of an electronic watt-hour meter having a transmission circuit having a function of transmitting a signal relating to measured power by automatic meter reading or the like, a means for stopping the function of the transmission circuit by a power failure signal is provided. Can be.

As described above, the electric energy transmission pulse output circuit,
By stopping the operation of the timed transmission pulse output circuit or the transmission circuit, current consumption can be reduced. The power failure detection circuit may specifically detect, for example, a power failure based on the pulse interval synchronized with the frequency of the AC power supply or the number of pulses during a certain period of time. Including a working photocoupler,
It may have a circuit that outputs a pulse synchronized with the frequency of the AC power supply.

The power failure detection circuit may have a rectifier circuit for converting an AC power supply to a DC power supply, and a voltage smoothing capacitor and a discharge resistor connected in parallel to the rectifier circuit. Good.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of an electronic watt-hour meter according to the present invention will be described in detail with reference to the drawings. In the following drawings, including FIG. 7 showing a conventional example,
The same reference numerals indicate the same or corresponding parts.

(First Embodiment) FIG. 1 shows a configuration of a main part of a first embodiment of an electronic watt-hour meter according to the present invention.
The configuration of the first embodiment shown in FIG. 1 is characterized in that a power failure detection circuit 10 is added to the conventional configuration shown in FIG.

That is, the power failure detection circuit 10 outputs a power failure signal to the control unit 3 before the power failure compensating power supply circuit 5 switches to the power source of the battery 4 when the AC power supply fails. In addition, when the AC power supply fails, the power supply of the power supply circuit 1 continues until the power failure detection circuit 10 detects the power failure.
Is a capacitor provided to prevent the power supply from discharging.

FIG. 2 shows a specific configuration of the power failure detection circuit 10. The power failure detection circuit 10 includes an AC pulse detection unit 21 and a power failure detection unit 22 as shown. As shown in FIG. 3, the AC pulse detection unit 21
The C sine wave 31 is converted into an AC pulse 32 having a pulse interval 33 corresponding to the cycle of the AC sine wave as shown in FIG. The AC pulse detection unit 21 is configured by a circuit including a photocoupler 41 as shown in FIG. 4, for example. The photocoupler 41 operates so as to turn on during the positive half cycle of the AC sine wave 31 and to turn off during the negative half cycle, so that an AC pulse 32 shown in FIG.
Actually, a negative pulse is obtained as the output of the circuit in FIG. 4, and the output is inverted by an inverter to obtain an AC pulse 32 shown in FIG.

Then, the power failure detection unit 22 shown in FIG.
The power failure is detected by counting the number of pulses of the AC pulse 32 at a pulse interval 33 or a predetermined time, and a power failure signal is output. For example, in the case of an alternating current of 50 Hz, the AC pulse interval 33 is usually 20 ms.
3 is detected to be 40 ms or longer, and a power failure is determined. In the case of counting the number of AC pulses, for example, 50
Hz alternating current, usually two AC pulses 3 in 40 ms
2 can be detected, but it is determined that a power failure has occurred if two were not detected within 50 ms.

The control unit 3 operates in response to a power failure signal from the power failure detection circuit 10 by switching the high speed reference clock to the low speed reference clock in order to reduce the current consumption of the circuit before the power failure compensation power supply circuit 5 switches to the power supply of the battery 4. I do.

At this time, a power transmission pulse output circuit 7 for outputting a power transmission pulse having a frequency proportional to the power.
, The output of the electric energy transmission pulse is stopped, and the timed transmission pulse output circuit 8 which has a function of measuring time and outputs a timed transmission pulse synchronized with this time stops the output of the timed transmission pulse and automatically reads the meter. The operation of the transmission circuit 9 that performs transmission such as the above is stopped.

As described above, in the electronic watt-hour meter shown in FIG. 1, the power calculation circuit 2 and the control unit 3 operate on the power supply from the power supply circuit 1 when energized, and when the power is cut off, the power calculation circuit 2
However, since the control unit 3 needs to hold a weighing value, the power source is switched to the power source of the battery 4 by the power failure compensation power supply circuit 5 to operate.

The control unit 3 uses the high-speed reference clock 12 to perform processing such as measurement and display of the amount of power when the power is turned on.
It outputs an electric energy transmission pulse, outputs a timed transmission pulse, and performs transmission. For this reason, the current consumption of the circuit during energization is large.

When the AC power supply fails, a power failure detection circuit 1
Before the power supply voltage of the power supply circuit 1 decreases at 0, the power failure detection circuit 10 detects a power failure and outputs a power failure signal, and the control unit 3 switches the high-speed reference clock 12 to the low-speed reference clock 13 according to the power failure signal. Stop the quantity transmission pulse, stop the timed transmission pulse, stop the transmission, reduce the current consumption of the circuit. For this reason, in the power failure compensation circuit 5, when switching to the power supply of the battery 4, the circuit current is small. For this reason,
There is no need to take measures to pass a large current through the battery.

As described above, by adopting the configuration of the first embodiment, even when the power supply of the power failure compensation power supply is switched to the battery power supply when the electronic watt-hour is lost, a large current flows through the battery. Since the battery does not flow, there is an effect that it is not necessary to take a measure against a large current in the battery.

The power failure detection circuit 10 does not detect a power failure at AC pulse intervals as shown in FIG. 3 but smoothes the rectifier circuit 51 of the AC power supply with a smoothing capacitor 52 as shown in FIG. May be provided with a discharge resistor 53 for discharging the charge of the smoothing capacitor 52. In this case, the values of the smoothing capacitor 52 and the discharge resistor 53 are adjusted to
It is detected that the voltage of the smoothing capacitor 52 has dropped before the voltage of the power supply has dropped, and a power failure is detected.

(Second Embodiment) Next, the configuration of the main part of a second embodiment of the electronic watt-hour meter according to the present invention is shown in FIG.
Shown in

In the first embodiment, the control unit 3 switches the reference clock in response to the power failure signal from the power failure detection circuit 10, but in the second embodiment, as shown in FIG. 61 is provided so that the reference clock of the control unit 3 is forcibly switched.

In the first embodiment, the control unit 3 stops the power transmission pulse output circuit 7, the timed transmission pulse output circuit 8, and the transmission circuit 9 by the power failure signal from the power failure detection circuit 10. However, in the second embodiment, as shown in FIG. 6, a power failure transmission pulse output circuit 7, a timed transmission pulse output circuit 8,
In addition, the operation of the transmission circuit 9 is stopped to reduce the circuit current consumption.

As described above, in the second embodiment,
Since the switching of the reference clock and the stoppage of the operations of the electric energy transmission pulse output circuit 7, the timed transmission pulse output circuit 8, and the transmission circuit 9 are performed by an external circuit different from the control unit 3, the control unit 3 Processing time is reduced.

Even with the configuration of the second embodiment, a large current does not flow through the battery at the moment when the power supply of the power failure compensation power supply is switched to the battery power supply in the event of a power failure of the electronic wattmeter. This has the effect of eliminating the need for a measure to flow a large current through the battery.

[0035]

As described above, according to the present invention,
Even when the power supply of the power failure compensation power supply is switched to the power supply from the battery in the event of a power failure of the electronic watt-hour meter, a large current does not flow to the battery, so there is no need to take measures to flow a large current to the battery. is there.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a first embodiment of an electronic watt-hour meter according to the present invention.

FIG. 2 is a block diagram showing a specific configuration of an example of a power failure detection circuit according to the first embodiment.

FIG. 3 is a signal waveform diagram for explaining the operation of the power failure detection circuit according to the first embodiment.

FIG. 4 shows A in the power failure detection circuit according to the first embodiment;
FIG. 3 is a circuit diagram showing a specific configuration of a C pulse detection unit.

FIG. 5 is a circuit diagram showing a specific configuration of another example of the power failure detection circuit according to the first embodiment.

FIG. 6 is a block diagram showing a configuration of a main part of a second embodiment of the electronic watt-hour meter according to the present invention.

FIG. 7 is a block diagram showing a configuration of a main part of a conventional electronic watt-hour meter.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 power supply circuit 2 power calculation circuit 3 control unit 4 battery 5 power failure compensation power supply circuit 6 power amount display unit 7 power amount transmission pulse output circuit 8 timed transmission pulse output circuit 9 transmission circuit 10 power failure Detection circuit 11: Capacitor 12: High-speed reference clock generation circuit 13: Low-speed reference clock generation circuit 21: AC pulse detection unit 22: Power failure detection unit 31: AC sine wave 32: AC pulse 33: AC pulse interval 41: Photocoupler 51 ... Rectifier circuit 52 ... Capacitor 53 ... Discharge resistor 61 ... Reference clock switching circuit

Claims (9)

[Claims] 1. A power supply circuit for converting an AC power supply to a DC power supply, a power failure compensation power supply circuit for switching to a battery power supply when the AC power supply fails, and a power for outputting a pulse having a frequency proportional to the measured power of the meter. An arithmetic circuit, a control unit that operates on the power failure compensation circuit power supply and integrates the pulses of the power arithmetic circuit to determine the amount of power, and a power failure before the AC power failure causes the power failure compensation power supply circuit to switch to battery power. An electronic watt-hour meter comprising: a power failure detection circuit that detects a power failure signal and outputs a power failure signal; and control means that controls the operation of the control unit based on the power failure signal output from the power failure detection circuit. 2. The control means according to claim 2, wherein said power failure signal causes said reference clock of said control unit to be shifted from a normally used first speed reference clock to a second speed reference clock lower than said first speed. 2. The electronic watt-hour meter according to claim 1, further comprising switching means for switching the power to the power. 3. An electronic watt-hour meter according to claim 2, wherein said switching means is provided outside said control section. 4. An electric energy transmission pulse output circuit for outputting an electric energy transmission pulse having a frequency proportional to the electric power, and the output of the electric energy transmission pulse output from the electric energy transmission pulse output circuit is stopped by the power failure signal. The electronic watt-hour meter according to any one of claims 1 to 3, further comprising: 5. A timed transmission pulse output circuit for outputting a timed transmission pulse synchronized with the time to an instrument having a function of measuring time, and an output of the timed transmission pulse output from the timed transmission pulse output circuit. 2. The apparatus according to claim 1, further comprising: means for stopping by a power failure signal.
An electronic watt-hour meter according to claim 4. 6. The transmission circuit according to claim 1, further comprising a transmission circuit having a function of transmitting a signal relating to measured power, and means for stopping the function of the transmission circuit by the power failure signal. Electronic watt-hour meter according to any one of the above. 7. The power failure detection circuit according to claim 1, wherein the power failure detection circuit detects a power failure based on an interval between pulses synchronized with a frequency of the AC power supply or a number of pulses during a predetermined time. Electronic watt-hour meter according to any one of the above. 8. The power failure detection circuit includes a photocoupler that is turned on and off by the AC power supply, and has a circuit that outputs a pulse synchronized with the frequency of the AC power supply. 7. The electronic wattmeter according to 7. 9. The power failure detection circuit according to claim 1, further comprising a rectifier circuit for converting the AC power into DC power, a voltage smoothing capacitor and a discharge resistor connected in parallel to the rectifier circuit. An electronic watt-hour meter according to any one of claims 1 to 6.