JPS6078357A - Watthour meter - Google Patents

Abstract

PURPOSE:To measure reactive and apparent powers or the like in addition to the effective power by adding a timer, which sets a prescribed delay time, to a computing-system watthour meter. CONSTITUTION:An auxiliary transformer 1 outputs a signal proportional to the load voltage of a feeder, and an auxiliary current transformer 2 outputs a signal proportional to the current flowed to the feeder. A timer 9 is added which sets a prescribed delay time in accordance with the relation in phase between the voltage and the current detected by these transformer 1 and current transformer 2. A microcomputer 7 controlled by the output signal of this timer 9 multiplies signals, which indicate values at points of time different in the prescribed delay time, out of signals corresponding to the voltage and the current from A/D converters 5 and 6 and measures the power. Thus, reactive and apparent powers or the like in addition to the effective power are measured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a watt-hour meter, and more particularly to a watt-hour meter having multiple computing-based functions.

[Technical background of the invention and its problems]

The watt-hour meter is configured to detect the voltage and current supplied to the load, and multiply the two to measure the power supplied to the load.

FIG. 1 shows a configuration diagram of a conventional computing type electronic power meter. Auxiliary transformer 7 detects the load voltage and outputs a signal proportional to this load voltage.

The auxiliary current transformer 2 detects the current consumption supplied to the load and outputs a signal proportional to this current consumption.

Both transformer 1 and current transformer 2 are attached to the load feeder line. The signals from the transformer 1 and current transformer 2 are input to analog-to-digital converters 5 and 6 via sample and hold circuits 3 and 4, and are converted to A at predetermined timing.
The D-converted signal is input to the microcomputer 7, multiplied to calculate power, and displayed on the display section 8. In this way, by sampling the voltage and current supplied to the load at a predetermined timing, converting it into a pulse train, and multiplying it by the microcomputer 7, only the effective power amount can be calculated.

Generally, it is sufficient to calculate only the active power amount as the power consumed by the load, but in some cases it may be necessary to calculate the reactive power amount or the apparent power amount.

In such a case, it would be very convenient if these reactive and apparent electric energies could be easily measured without making any major changes to the configuration of the electric energy meter.

[Purpose of the invention]

An object of the present invention is to provide a watt-hour meter that can measure not only active power but also reactive power, apparent power, etc. with high accuracy by simply improving the conventional computing-type watt-hour meter.

[Summary of the invention]

In order to achieve the above object, the present invention provides a timer for setting a predetermined delay time in a watthour meter that measures the power supplied to the load by multiplying the voltage and current supplied to the load, The method is characterized in that the voltage and current values are multiplied by signals indicating values at points in time that differ from each other by a delay time.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings. In the following drawings, the same parts as shown in FIG. 1 are given the same reference numerals, and their explanations will be omitted. FIG. 2 is a block diagram showing an embodiment of the present invention. The difference from the conventional configuration shown in FIG. The point is that the microcomputer 7 operates according to the output signal.

Next, the operation of the circuit shown in FIG. 2 will be explained. A signal proportional to the load voltage of the power supply line is detected by the auxiliary transformer 1, which is converted into a pulse train by the analog-to-digital converter 5 via the sample-and-hold circuit 3 at predetermined timings and stored in the memory section of the microcomputer 7. Save it up.

On the other hand, a signal proportional to the current consumption of the load is detected by an auxiliary current transformer 2, which is similarly converted into a pulse train by an analog-to-digital converter 6 via a sample-and-hold circuit 4, and then stored in another memory section of the microcomputer 7. Store it in.

On the other hand, timer 9 produces signals as shown as A and B in FIG. In FIG. 3, e represents the load voltage, and ei represents the load current. For example, to detect reactive power, the load voltage signal e 2 may be delayed by 2 volts and multiplied by the load current signal ei .

Therefore, it is sufficient to create a signal B having a pulse width of i from the load voltage signal ev, and hold the stored data of the voltage signal ev for a time corresponding to this pulse width.

That is, the microcomputer 7 starts multiplication by the current signal e at the falling edge of the pulse of the signal B, thereby making it possible to calculate the reactive power. Similarly, in order to detect the apparent power, the timer 9 generates a signal A.
You can use Signal A is voltage signal ev and current signal ei
It has a pulse width corresponding to the phase difference between the two. In order to detect the apparent power, it is sufficient to hold the data (2) of the voltage signal e stored in the memory for a time corresponding to the pulse width of this signal A. In other words, at the falling edge of the pulse of signal A, the microcomputer 7 multiplies the current signal e.
should be executed.

In this way, by controlling the multiplication execution time of the data stored in the memory section of the microcomputer 7 using the output from the timer 9, it is possible to calculate not only the active power but also the reactive power and the apparent power.

FIG. 4 is a block diagram showing another embodiment of the present invention. In the example shown in Figure 4, the sample and hold circuit is removed and the transformer 1
A delay circuit 10 is inserted between the current transformer 2 and the analog/digital converter 6, and a delay circuit 11 is inserted between the current transformer 2 and the analog/digital converter 6, and the delay time of this delay circuit is controlled by the output of the timer 9. It is configured to do so.

As the delay circuit 10゜11, a random shift register or C
Analog memories such as OD and BBD can be used.

In this configuration, unlike the case shown in FIG. 2, the voltage signal or current signal itself is delayed by a predetermined time and stored in the microcomputer 7, so the microcomputer 7 can directly multiply the signal. Bye.

Note that two analog-to-digital converters 5 and 6 in FIGS. 2 and 4 are not necessarily required for the voltage signal path and the current signal path, and both may be combined into one and switched by a switch. . .

〔Effect of the invention〕

As described above in detail based on the embodiments, the present invention includes a timer that sets a predetermined time according to the phase relationship between voltage and current, and means for delaying the voltage or current according to the output of this timer. This has the advantage that the extremely simple configuration of the device enables it to measure not only active power, which conventional watthour meters have, but also reactive power, apparent power, and the like.

In particular, until now, reactive power, apparent power, etc. have been measured using separate devices, but with the watthour meter of the present invention, all can be measured with one device, making it economically viable. It is extremely advantageous. Additionally, an error may occur in the phase angle between the voltage signal and current signal during signal conversion, but this phase angle error can be easily removed by changing the effective time multiplication of the data stored in the microcomputer. It also has the advantage of being much more accurate than conventional electricity meters.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a conventional watt-hour meter, FIG. 2 is a configuration diagram showing an embodiment of the present invention, FIG. 3 is a waveform diagram for explaining the operation of a timer used in this invention, and FIG. The figure is a configuration diagram showing another embodiment of the present invention. 1... Auxiliary transformer, 2... Auxiliary current transformer, 5, 6...
・Analog-digital converter, 7...Microcomputer, 9...Timer, 10, 11...Delay circuit. Figure 1 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) A watt-hour meter that measures the power supplied to the load by multiplying the voltage and current supplied to the load, and includes an auxiliary transformer (1) that generates a signal proportional to the load voltage of the power supply line.
), an auxiliary current transformer (2) that generates a signal proportional to the current flowing in the feeder line, and an analog converter that converts the signals from the auxiliary transformer (1) and the auxiliary current transformer (2) into digital signals. - In a power meter equipped with a digital converter (5, 6) and a microcombinator (7) that receives the outputs of the analog-to-digital converters (5, 6) and multiplies them. , a timer (9) for setting a predetermined delay time; and a timer (9) for setting a predetermined delay time, and multiplying the values of the voltage and current by signals indicating values at points in time that are different from each other by the delay time.