JPH11108973A - Watthour meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a watthour meter which can be reduced in size, as small as possible and can be replaced easily. SOLUTION: The watthour meter comprises at least one through current transformers 14, 16 for detecting a load current being employed for measuring electric energy. The through current transformers 14, 16 are split so that the primary conductors, i.e., feeder lines 1, 2 feeding a load current, can pass through the core window without being cut off. The core window body is exposed to the outside of main body provided with voltage terminals 1V, 2V and 3V receiving a voltage being employed for measuring electric energy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a watt hour meter for measuring the amount of power consumed by general consumers and the like.

[0002]

2. Description of the Related Art A watt-hour meter generally has a voltage terminal and a current terminal for introducing a load voltage and a load current due to its measurement principle. For example, as shown in FIG. 4, in a single-phase three-wire type or three-phase three-wire type power supply circuit, three power supply lines 1K, 2K, and 3K are connected to power supply terminals 1S, 2S, and 3S of a watt hour meter 40. Connected, load side terminals 1L, 2L,
The actual feeder lines 1Q, 2Q, 3Q from 3L to the customer are derived. Although not shown in the figure, the power supply terminal 1S,
Two current transformers are connected between the 3S and the load terminals 1L and 3L, respectively. A load voltage for measuring the electric energy is introduced into the electric energy meter main body 41 from the power supply terminals 1S, 2S, 3S. The watt-hour meter 40 measures the amount of power based on the input voltage and current according to a well-known principle, and displays the power consumption of the load on a display unit (not shown). FIG. 4 illustrates a single-phase three-wire feed line of a type in which the center feed line 2K is grounded. The illustrated watt-hour meter 40 includes terminal communication terminals DT and SG.

[0003] The maximum rated current of this type of stand-alone meter, which leads the load current directly into the watt-hour meter body 41, is currently 2
It is about 00A. However, the maximum rated current tends to increase, and it is expected that the current will increase further in the future.

[0004]

In the single meter type watt-hour meter, the current coil wire and the connection wire of the current transformer accommodated in the main body 41 become thicker and more rigid as the rated current becomes larger. In addition, the connection terminal for current becomes large. Along with this, the instrument terminal becomes large, and the instrument as a whole must be large.

Further, as the rated current increases, the temperature rise and the voltage drop due to the load current increase, making it difficult to construct a low-load instrument. In addition, when replacing the meter, the power supply line must be temporarily removed from the watt-hour meter in a power outage state, and then replaced.

Accordingly, an object of the present invention is to provide a watt-hour meter which can be configured as small as possible and which can be easily replaced.

[0007]

In order to solve the above-mentioned problems, a watt-hour meter according to the present invention comprises at least one feed-through current transformer for detecting a load current used for measuring an electric energy, and comprises a feed-through current transformer. The current transformer is configured as a split type in order to penetrate the iron core window without cutting the power supply line through which the load current flows as the primary conductor, and at least the iron core window is exposed to the outside of the main body. A voltage terminal for introducing a voltage used for measuring the electric energy is provided.

[0008] One of the cores of the split-type feedthrough current transformer is fixed in the main body with a secondary winding attached thereto, and the other iron core is provided with one of the cores without the secondary winding attached thereto. It is preferable that the magnetic path is pivotally attached to the iron core so that the magnetic path can be freely opened and closed.

In a watt hour meter arranged on a single-phase three-wire type or three-phase three-wire type power supply line, two feed-through current transformers are provided. Preferably, a voltage terminal is provided, and a through current transformer is provided on both sides of the voltage terminal.

[0010]

FIG. 1 shows an embodiment of the present invention. This embodiment shows a conceptual diagram of a watt-hour meter applied to a single-phase three-wire feeder line, and three voltage terminals 1V, 2V and 3V are arranged, and penetrating current transformers 14 and 16 are arranged on both sides of the 2V and 3V. Of the three feeder lines 1, 2, and 3, the first feeder line 1 passes through the core window of the feedthrough current transformer 14, and the third feeder line 3 passes through the core window of the feedthrough current transformer 16. The second feeder line 2 that penetrates and is grounded
Are directly connected to the input terminals 4, 6, 5 of the customer, respectively. Load voltages are led to the voltage terminals 1V, 2V, and 3V from the input terminals 4, 5, and 6 of the consumer via voltage signal lines 7, 8, and 9 separately from the power supply lines 1 to 3.

The iron cores of the penetration type current transformers 14 and 16 are formed in a split type so that the feeder line can be freely penetrated through the core window or removed therefrom. The secondary windings of the through-type current transformers 14, 16 and the voltage terminals 1V, 2V,
From 3 V, a current and a voltage used for measuring the electric energy are respectively introduced into the electric energy meter main body 12, and the electric energy is measured according to a well-known measurement principle. The through current transformers 14 and 16 have the same structure.

A feature of the watt-hour meter 10 shown in FIG. 1 is that it does not have a current terminal, that is, the power supply lines 1, 2, and 3 are directly disconnected without being disconnected at the watt-hour meter. , 5,6. Therefore, not only can the electric energy meter be configured to be small and inexpensive, but also the replacement operation of the meter can be performed in a live state. further,
Since there is no need to connect to or remove from the current terminal, which requires considerable tightening force, at the time of certification or testing of the instrument, labor can be saved.

FIG. 2A shows a state in which the through current transformer 14 configured as a split type has a magnetic path opened. As is clear from FIG. 2A, the iron core 20 of the feedthrough current transformer 14 has a first iron core portion 20a on which the secondary winding 22 is mounted.
And a second core portion 20b to which no secondary winding is attached, and is housed in the casing 24. First
The core portion 20a is fixedly arranged on the electric energy meter 10, and the second core portion 20b is pivotally attached to the casing 24 so that the magnetic path of the iron core 20 can be freely opened and closed. The second core portion 20b of the current transformer 14 is housed in an instrument terminal box 26 provided at the lower end of the electric energy meter 10, and the voltage terminals 1V, 2V, and 3V are shown in FIG. Thus, it is provided on a terminal plate 28 formed in the instrument terminal box 26.

In this type of split-type current transformer, the magnetic characteristics of the split contact surface of the iron core and the relative position of the penetrating primary conductor with respect to the iron core can be a problem in accuracy of the current transformer. Therefore, the split contact surfaces of the split cores are tightened with a band or the like so that the air gap at the time of contact is as small as possible to prevent the generation of magnetic flux leakage and to make the magnetic characteristics as stable as possible. Measures such as protecting the cut surface with thin silicon resin or the like.
By maintaining a certain degree of harmony between the thickness of the feeder line and the size of the iron core window 30 penetrating the feeder line, a problem of characteristic variation that can occur due to the relative position of the primary conductor (feeder line) in the iron core window 30. Can be made substantially negligible.

FIGS. 3A and 3B are enlarged views showing a state in which the magnetic path of the iron core 20 of the feedthrough type current transformer is closed. The iron core 20 includes a first iron core portion 20a and a second iron core portion 20b. The entire current transformer is housed in the casing 24. Due to the function of the split current transformer, the casing 24 also has a first case portion 24a for housing the iron core portion 20a and a second case housing for the iron core portion 20b. And a casing part 24b. The casing 24 forms a penetrating window that shares the iron core 20 and the iron core window 30. First core part 2 fixedly arranged
A lead wire 22a is led out of the secondary winding 22 mounted on the lead wire 0a, and is led to a power meter main body (not shown). The second core portion 20b to which the secondary winding is not mounted can be freely opened and closed by using a pivot portion 24c provided on one side of the casing 24 as a rotation axis to open a magnetic path (FIG. 2A )
By doing so, the power supply line can be penetrated into the iron core window 30 in a live state without cutting. After arranging the feeder wire in the core window 30, the divided surface of the second core portion 20b is brought into contact with the divided surface of the first core portion 20a, and the two core portions are slightly butted against each other. The casing 24 is locked to be openable and closable by a locking portion 24d provided on a side opposite to the pivotal portion 24c.

When the electric energy meter described above is newly arranged on the feeder line, the electric energy meter is attached to a predetermined position, and then the locking portion 24d is released to split the iron core 20. The iron core window 30 is opened, and the power supply line is penetrated therethrough without disconnection or connection work without interruption and in a live state, and is again assembled by the locking portion 24d. In the same way as above, when the watt hour meter is removed for replacement etc., without using the features of the split type current transformer and disconnecting the power supply line, etc. The work can be easily performed simply by operating the locking portion 24d.

The electric energy meter provided on the distribution line is not frequently removed or replaced, but once installed, it is left attached for at least 10 years, which is the validity period of the single meter. Yes,
There is no need to make the openable structure very complicated. In some cases, a band clamp type may be used.

The watt-hour meter of the present invention is particularly suitable as an electronic watt-hour meter. This is because the load connected to the current transformer secondary circuit of the electronic watt-hour meter is small, the capacity of the signal level can be almost small, and the output of the feedthrough type current transformer with one primary winding turn can be used. The reason for this is that sufficient characteristics can be obtained.

[0019]

According to the present invention, a small size without a current terminal
In addition to being able to provide an inexpensive energy meter, the removal and installation of the meter can be performed quickly and uninterruptedly, in a live state, by providing a penetrating / split-type current transformer. it can.

Further, according to the present invention, since a large current does not flow inside the meter and there is no primary current terminal, the power loss of the meter can be suppressed small and the rise in the internal temperature can be suppressed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing one embodiment of the entire configuration of a watt hour meter according to the present invention.

2A is a side view showing a state in which the magnetic path of the feedthrough current transformer in the electric energy meter of FIG. 1 is opened, and FIG. 2B is a side view showing the magnetism of the feedthrough current transformer in the electric energy meter of FIG. The front view showing the state where the road was closed.

FIG. 3A is a front view of a through-type current transformer incorporated in a watt-hour meter according to the present invention, and FIG. 3B is a side view of the current transformer.

FIG. 4 is an explanatory diagram for explaining a connection state between a conventional watt-hour meter and a power supply line.

[Explanation of symbols]

 1,2,3 Power supply line 1V, 2V, 3V Voltage terminal 4,5,6 Customer input terminal 7,8,9 Voltage signal line 10 Watt hour meter 12 Watt hour meter main body 14,16 Penetrating current transformer 20 split Type iron core 20a First iron core part 20b Second iron core part 22 Secondary winding 24 Casing 24a First case part 24b Second case part 24c Pivot part 24d Lock part 30 Iron core window

Claims (3)

[Claims] 1. A power supply system comprising at least one feed-through current transformer for detecting a load current used for measuring an electric energy, wherein the feed-through current transformer cuts off a feeder through which a load current flows as a primary conductor. In order to penetrate through the iron core window without being divided, at least the iron core window is exposed to the outside of the main body, and the outside of the main body is provided with a voltage terminal for introducing a voltage used for measuring the electric energy. An electric energy meter characterized by the above-mentioned. 2. One of the cores of the feedthrough type current transformer configured as a split type has a secondary winding mounted thereon and is fixed in the main body, and the other core has a secondary winding mounted thereon. 2. The watt-hour meter according to claim 1, wherein the electric power meter is pivotally connected to the one core portion so as to freely open and close the magnetic path. 3. A watt hour meter arranged on a single-phase three-wire type or three-phase three-wire type power supply line, wherein two through-type current transformers are provided and terminals on the front surface of the watt-hour meter main body. 3. The watt-hour meter according to claim 1, wherein a voltage terminal is disposed at a center of the portion, and the through-type current transformers are disposed on both sides of the voltage terminal. 4.