JPH04346074A - Electronic type watthour meter - Google Patents

Abstract

PURPOSE:To obtain a single-phase three-wire electronic type watthour meter easy to prepare and capable of preventing the burnout of load even when load is out of balance. CONSTITUTION:Low resistance elements 6A, 6B are connected to the current and 1L terminals in series and resistance voltage dividers 7A, 7B, 7C, 7D are connected across the both terminals of the low resistance elements 6A, 6B and a neutral phase current wire 4 to obtain a low potential voltage signal and a current signal. A neutral wire 4A is branched in a meter and the low resistance elements 6A, 6B are connected to respective branch wires 4B, 4C and the voltage drop components of the low resistance elements 6A, 6B are inputted to an electronic circuit 12 as current signals.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic watt-hour meter, and more particularly to an electronic watt-hour meter with a different means for detecting load current.

0003

2. Description of the Related Art FIG. 7 shows a connection diagram between a conventional single-phase three-wire electronic watt-hour meter (hereinafter referred to as a watt-hour meter) and a load. In FIG. 7, a single-phase three-wire power meter 25 is attached to the consumer 16, and terminals 1S, 2S, and 3S of this power meter 25 are attached to the consumer 16.
A power supply side connection wire 1 connected to a single-phase three-wire power supply line (not shown) is connected to. Of these, the electric wire 1a connected to the terminal 1S is connected to one side of the two voltage lines of the feeder line (not shown), and the electric wire 1b connected to the terminal 2S is connected to the neutral line of the feeder line (not shown), and to the terminal 3S. The connected electric wires 1c are respectively connected to the other sides of two voltage lines of a power supply line (not shown).

[0004] Inside the electricity meter 25, terminals 1S and 1L
A current line 3 is connected between them, a current line 4 is connected between the terminals 2S and 2L, a current line 5 is connected between the terminals 3S and 3L, and the terminal 1L
, 2L, and 3L are connected to a load-side connection wire 2. Of these, the electric wire 2a is connected to the load 17A, and the electric wire 2c is connected to the load 17A.
The electric wire 2b connected to the terminal 7B and the terminal 2L is branched in the middle and connected to a load 17A and a load 17B.

FIG. 8 shows an internal wiring diagram of the electricity meter 25 shown in FIG. 2. As shown in FIG. In FIG. 8, the current line 3 passes through the through-type current transformer 41A, and the current line 5 also passes through the through-type current transformer 41A.
It passes through 1B. Resistive voltage dividers 7A and 7C are provided between the current line 3 and the current line 4, and between the current line 5 and the current line 4.
are provided with the internal low resistance 14 side connected to the current line 4, and on the resistance voltage divider 7A side, the connection part between the low resistance 14 and the high resistance 13 is connected to the voltage signal line 8A to the terminal P1 of the electronic circuit 12. and on the resistance voltage divider 7 side, a low resistance 14
The connecting portion between the high resistance 13 and the high resistance 13 is connected to the terminal P3 of the electronic circuit 12 by a voltage signal line 8B, and the current line 4 and the ground terminal G of the electronic circuit 12 are connected by a ground line 10.

On the other hand, the detection signal of the current flowing through the current line 3 detected by the through-type current transformer 41A is input to the internal multiplier circuit via the terminal I1 of the electronic circuit 12 via the current signal line 9A, and is similarly The detection signal of the current flowing through the current line 5 detected by the current transformer 41B is inputted via the terminal I3 of the electronic circuit 12 on the current signal line 9B, and is multiplied by the voltage signal inputted from the terminals P1 and P3. The electric energy of the 1 side (current line 3 side) and the 3 side (current line 5 side) is calculated, and the result of adding these two is displayed as the electric energy of the loads 17A and 17B on a display section (not shown). . Note that, as described above, a potential transformer may be used instead of the resistive voltage dividers 7A and 7B.

[0007] In the watt-hour meter configured as described above, the current signal input to the electronic circuit 12 through the current signal lines 9A, 9B is insulated from the potential of the current lines 3, 5 by the current transformers 41A, 41B. The voltage signal input to the electronic circuit 12 through the voltage signal lines 8A and 8B is at a level that can be input to the electronic circuit 12 based on the ratio of the low resistance 14 to the high resistance 13 on the current line 4 side connected to the neutral line. is set to .

[0008]

[Problem to be Solved by the Invention] However, in the electricity meter configured as described above, the current transformers 41A, 41B
Not only does it take a long time to manufacture because of poor availability, but the current transformers 41A and 41B are expensive, making the watt-hour meter expensive as well. Therefore, instead of the current transformers 41A and 41B, it is possible to use a shunt to detect the currents in the current lines 3 and 5. However, in this case, the potentials of the current lines 3 and 5 are directly connected to the electronic circuit 1.
2, it cannot be used because the withstand voltage of the electronic components of the electronic circuit cannot be maintained.

On the other hand, as shown in FIG. 7, the load 17A of the consumer 16 is connected to the load 1
7B is connected between the load side connecting wire 2a connected to the terminal 2L and the terminal 3L, if the connection between the terminal 2L and the load side connecting wire 2a is disconnected, the load 17A,
Due to the unbalance between the 17Bs, a voltage exceeding the rating is applied to the load on one side, which not only shortens the life of the electrical equipment but also risks burning it out.

[0010] Also, when the terminal 2S and the power supply side connection wire connected to this terminal 2S are disconnected, a high voltage is applied to the load, and in this case, it can be detected by the power outage display on the watt-hour meter. If you are not aware of this, a similar accident will occur.

Therefore, the object of the first invention is to obtain a watthour meter that can be easily manufactured without increasing the withstand voltage value of the electronic circuit, and the object of the second invention is to obtain a watthour meter that can be easily manufactured without increasing the withstand voltage value of the electronic circuit. The object of the present invention is to obtain a watthour meter that can prevent load burnout even when the load is unbalanced. [Structure of the invention]

0012

[Means and effects for solving the problem] The first invention is
In an electronic watt-hour meter that uses a voltage divider to detect the voltage of a voltage line based on a neutral line, and uses an electronic circuit to calculate the load power from this detected value and the detected value of the load current flowing through the neutral line or voltage line. By connecting a low resistance element that detects the load current in series with the neutral line or voltage line, the load current can be detected at a low potential using an easily available low resistance element, and the withstand voltage value of the electronic circuit can be determined. This is an electronic watt-hour meter that can be easily manufactured without increasing costs.

[0013] Also, the second invention is an electronic power system in which the voltage of a voltage line with respect to a neutral line is detected by a voltage divider, and the load power is calculated by an electronic circuit from this detected value and the detected value of the load current. In a quantity meter, by branching the neutral wire and connecting a low resistance element in series to each branch line to detect the load current, the load current can be detected at a low potential using an easily available low resistance element. This is an electronic watt-hour meter that is easy to manufacture and can prevent load burnout when the load is unbalanced.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the electricity meter of the present invention will be described below with reference to the drawings. However, parts that overlap with those in FIGS. 7 and 8 are given the same reference numerals and their explanations will be omitted.

FIG. 1 is an internal wiring diagram of a power meter according to the first invention. In FIG. 1, there is a line between the current line 3A connected to the terminal 1S and the current line 1L connected to the terminal 1L.
A shunt as the side low resistance element 6A is connected, and the terminal 3S
A shunt as a third-side low resistance element 6B is also connected between the current line 5A connected to the terminal 3L and the current line 5B connected to the terminal 3L.

Among these, a resistive voltage divider 7A is connected between the connection part of the current line 3A connected to the power supply side of the low resistance element 6A and the current line 4, with the low resistance 14 side being the current line 4 side. Similarly, a resistive voltage divider 7B is connected between the current line 4 and the connection part of the current line 3B connected to the load side of the low resistance element 6A.
are connected with the low resistance 14 side facing the current line 4 side. Similarly, resistance voltage dividers 7C and 7D are connected to the low resistance 14 between the power supply side terminal and load side terminal of the low resistance element 6B and the current line 4.
It is connected with its side facing the current line 4 side.

These resistance voltage dividers 7A, 7B, 7C, 7
Among D, the voltage signal line 8A is connected between the connection part between the low resistance 14 and the high resistance 13 of the resistance voltage divider 7A and the terminal P1 of the electronic circuit 12, and the voltage signal line 8A is connected between the low resistance 14 and the high resistance of the resistance voltage divider 7C. A voltage signal line 8B is connected between the connection portion 13 and the terminal P3 of the electronic circuit 12. Similarly, the connection between the low resistance 14 and high resistance 13 of the resistive voltage divider 7B and the electronic circuit 1
A current signal line 9A is connected between the terminal I1 of the electronic circuit 12, and a current signal line 9B is connected between the connection between the low resistance 14 and the high resistance 13 of the resistive voltage divider 7D and the terminal I2 of the electronic circuit 12. ing.

In the watt-hour meter configured as described above, the terminal 1S is calculated from the difference between the current signal input to the terminal I1 and the voltage signal input to the terminal P1 (obtained by a differential amplifier, for example).
, 1L is detected, and the power on the 1 side is calculated from this detection result and the value of the voltage signal input to the terminal P1. Similarly, the current signal input to terminal I2 and P3
The current flowing between terminals 3S and 3L is detected from the difference between the voltage signals input to terminal P3, and the power on side 3 is calculated from this detection result and the value of the voltage signal input to terminal P3. The above-mentioned power on the first side is added and the power consumption of the load is displayed on a display section (not shown).

Therefore, in the power meter configured as described above, the current value is detected at a low potential by the low resistance 14 of the small and lightweight voltage dividing resistors 7B and 7D, and the current value is detected at a low potential by the low resistance 14 of the small and lightweight voltage dividing resistors 7B and 7D. Electronic circuit 1 as a current signal input at 9B
2, it can be input to an electronic circuit without using a conventional current transformer, making it compact and
The electricity meter is lightweight and easy to manufacture. Note that conventional wattmeters detect current using current transformers and cannot measure direct current, but the present invention can also measure direct current power.

FIG. 2 shows another embodiment of the watt-hour meter of the present invention, in which a composite resistive element 27 is used in place of the resistive voltage dividers 7A and 7B in FIG. 1, and the resistive voltage dividers 7C and 7D in FIG. Shows when the same thing was done. In this case, the temperature rise of the internal high resistance 13 and low resistance 14 can be made almost uniform, so
This has the advantage of suppressing temperature-related variations in the detection signal and increasing the accuracy of measuring electric power.

Next, FIG. 3 is an internal wiring diagram showing the watthour meter of the second invention. In FIG. 3, the terminal portion 21 includes
Terminal 2La and terminal 2Lb are provided between terminal 3L and terminal 1L. Of these, an internal current line 4B is connected to the terminal 2La, a shunt as a low resistance element 6A is connected between this current line 4B and the current line 4A, and an internal current line is connected to the terminal 2Lb. 4C is connected and this current line 4
A current shunt serving as a low resistance element 6B is connected between C and the current line 4A.

A current signal line 9 connected to the terminal I1 of the electronic circuit 12 is connected to the connection portion between the low resistance element 6A and the current line 4B.
The current signal line 9B, which is connected to the terminal I3 of the electronic circuit 12, is connected to the connection portion between the low resistance element 6B and the current line 4C. Further, as shown in FIG. 4, a load 17A is connected to the terminal 1L and the terminal 2La, and a load 17B is connected to the terminal 2Lb and the terminal 3L by a load-side connecting wire 22, respectively.

In the watt-hour meter configured as described above, the load current flowing between the terminals 2S and 2La is detected by the current signal line 9A, and this current signal is combined with the low resistance 14 and high resistance 13 of the resistor voltage divider 7A. The power on the 1 side is calculated from the difference between the voltage signals of the current line 3 detected by the ratio and inputted through the voltage signal line 8A, and the voltage signal. Similarly, the load current flowing between the terminals 2S and 2Lb is detected by the current signal line 9B, detected by this detection signal and the ratio of the low resistance 14 to the high resistance 13 of the resistor voltage divider 7B, and inputted to the voltage signal line 8B. The power on the third side is calculated from the difference between the voltage signals of the current line 5 and this voltage signal, and is added to the power on the first side, and the power supplied to the consumer 16 is displayed on a display section (not shown).

In the watt-hour meter configured as described above, the current flowing through the current lines 4B, 4C is changed to the potential of the load side terminals of the low resistance elements 6A, 6B, which have one side connected to the current line 4A, which is at approximately ground potential. Since the power consumption can be detected using the low resistance elements 6A and 6B, which are inexpensive and easily available, without increasing the withstand voltage value of the electronic circuit, the watthour meter is easy to manufacture.

Furthermore, if any of the connections between the terminals 1L, 2La, 2Lb and the terminal 3L and the load-side connecting wire 22 is disconnected, or if there is an imbalance between the loads 17A and 17B, No high voltage is applied to that load.

FIG. 5 shows another embodiment of the electricity meter of the second invention, and FIG. 6 shows a 100V load 17A of the consumer 26.
, 17B and the wiring diagram connected to the 200V load 17C.

In FIG. 5, terminal 1 of the electricity meter of FIG.
A low resistance element 6A is also connected to the current lines 3A and 3B corresponding to the current lines between S and 1L, and the current signal detected by this low resistance element 6A is input to the terminal I of the electronic circuit 32. In this case, the current flowing through the 200V load 17C is the current flowing between the terminals 1S and 1L, and the current flowing between the terminals 2S and 2La.
The load power is calculated from the difference in the current flowing between the terminals P1 and P3, and is calculated from the product of the voltage signals input to the terminals P1 and P3, and displayed on a display section (not shown). As a result, terminals 1L and 2L
Even if the connections between a, 2Lb and terminal 3L and the load-side connecting wire are disconnected, not only will excessive voltage not be applied to the loads 17A and 17B, but the power consumption of the 200V load will be displayed separately, making it easier than ever before. There was no difference in electricity charges compared to 100V loads.It is also possible to increase the 200V power supply.

[0028]

As described above, according to the first invention, the voltage of the voltage line with respect to the neutral line is detected by a voltage divider, and this detected value and the detected value of the load current flowing through the neutral line or the voltage line are combined. In an electronic watt-hour meter that calculates load power using an electronic circuit, a low-resistance element that detects the load current is connected in series with the neutral line or voltage line. Since the current is detected at a low potential, it is possible to obtain an electronic watt-hour meter that can be easily manufactured without increasing the withstand voltage value of the electronic circuit.

According to the second invention, the voltage of the voltage line with respect to the neutral line is detected by a voltage divider, and the load power is calculated by an electronic circuit from this detected value and the detected value of the load current. In a type watt-hour meter, by branching the neutral line and connecting a low-resistance element that detects the load current in series to each branch line, the load current can be detected at a low potential using easily available low-resistance elements. ,
It is possible to obtain an electronic watt-hour meter that is easy to manufacture and can prevent load burnout when the load is unbalanced.

[Brief explanation of the drawing]

FIG. 1 is an internal wiring diagram showing an embodiment of an electronic watt-hour meter according to a first invention.

FIG. 2 is a partial connection diagram showing another embodiment of the electronic watt-hour meter of the first invention.

FIG. 3 is an internal wiring diagram showing an embodiment of the electronic watt-hour meter of the second invention.

FIG. 4 is a connection diagram showing the operation of the electronic watt-hour meter of the second invention.

FIG. 5 is an internal wiring diagram showing another embodiment of the electronic watt-hour meter of the second invention.

FIG. 6 is a connection diagram showing the operation of another embodiment of the electronic watt-hour meter of the second invention.

FIG. 7 is a diagram showing a connection between a conventional electronic watt-hour meter and a load.

FIG. 8 is an internal wiring diagram of a conventional electronic watt-hour meter.

[Explanation of symbols]

1... Power supply side connection wire, 2, 22... Load side connection wire, 3,
3A, 3B...1 side current line, 4, 4A, 4B, 4C...neutral phase current line, 5, 5A, 5B...3 side current line, 6A,
6B, 6C...Low resistance element, 7A, 7B, 7C, 7D...Resistance voltage divider, 8A, 8B...Voltage signal line, 9A, 9B, 9C
...Current signal line, 10...Grounding wire, 11, 21...Terminal section, 1
2, 32...Electronic circuit, 13...High resistance, 14...Low resistance.

Claims (2)

[Claims] Claim 1: A voltage divider detects the voltage of a voltage line with a neutral line as a reference, and an electronic circuit calculates load power from this detected value and a detected value of a load current flowing through the neutral line or the voltage line. An electronic watt-hour meter characterized in that a low-resistance element for detecting the load current is connected in series with the neutral line or the voltage line. 2. An electronic watt-hour meter that detects the voltage of a voltage line with a neutral line as a reference using a voltage divider, and calculates load power using an electronic circuit from this detected value and a detected value of load current, 1. An electronic watt-hour meter, characterized in that a power line is branched, and a low resistance element for detecting the load current is connected in series to each branch line.