Embodiments of the invention in general relates to the field of utility meters for metering electrical power consumption and more particularly to detection of Neutral missing tamper in energy meter and to provide operation during neutral missing to tackle energy defrauding.
BACKGROUND OF THE INVENTION
Energy meter is used for measuring the energy utilises by the electric load is known as the energy meter. The energy is the total power consumed and utilised by the load at a particular interval of time. It is used in domestic and industrial AC circuit for measuring the power consumption.
The energy meter is primarily powered from mains, which is provided between the line and neutral connections. In an exemplary configuration of the prior art, as in Fig. 1A, the voltage between Line_In and Neutral_In and the current sensed across a shunt connected between Lineln and LineOut calculate the energy consumption. The sum of the voltage current product helps calculate the active power. Active power is also equivalent to the product of the root-mean-square, RMS, voltage and the RMS current multiplied by the cosine of the angle between the voltage and current. The meter accumulates active power over time to generate the active energy readings, which become the quantity for which the consumer is billed.
Energy can be stolen through different meter tampering techniques to prevent meters from accurately registering consumption. In an exemplary technique, one disconnects the neutral from a meter and connects the consumer's load to earth

instead. Then the consumers can alter the active energy readings in single-phase meters by disconnecting the neutral wire. As in Fig. IB, if the neutral is disconnected, the voltage measured would be 0 V, which would lead to a 0-W measured value for active power.
Thus, electricity energy meters must be able to either detect neutral disconnections and other types of tampering, or be hardened to prevent energy theft. In energy metering domain making a tamper proof energy measurement is complicated task. There are different tampers which are subjected to energy meter. One among those tampers are Neutral/potential missing. Basically, Neutral/potential missing tamper is of voltage missing nature. There are few techniques to detect this neutral/potential missing. Those are: (a) Using power transformer as Neutral Missing CT; and (b) Using Active Low/High detection with the help of auxiliary supply. Above techniques are inaccurate at lower currents and solutions are costly and complicated in assembly.
In view of the prior art, there is a dire need of a mechanism to detect Neutral missing tamper in energy meter and to provide operation during neutral missing to tackle energy defrauding.
SUMMARY OF THE INVENTION
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.
According to one aspect of the present invention, energy meter for metering of electrical energy and neutral missing tamper detection, said meter comprising:

a plurality of source terminals (SI, S2, S3, SN), wherein each source terminal (SI,
S2, S3, SN) is operably connected to a phase terminal (L) to operate as a phase
channel, or operably connected to a neutral terminal (N) to operate as a neutral
channel;
a plurality of load terminals (LI, L2, L3, LN), wherein each load terminal (LI,
L2, L3, LN) is operably connected to provide electrical energy to the load;
characterized in that:
a shunt operably connected to a phase channel to operate as a current sensor for
the phase channel, and a current transformer, CT, operably connected to a neutral
channel to operate as a current sensor for the neutral channel; and
an operational amplifier, Op-Amp, comprising a plurality of input and output
terminals, wherein the current sensor outputs of the phase channel and the current
sensor outputs of the neutral channel are fed as input to the plurality of input
terminals (1, 2, 3, 4) of the Op-Amp, and the Op-Amp is configured to:
operate as a differential Op-Amp, when the energy meter is subjected to neutral
missing tamper, and detect the difference in potential at its input terminals (1, 2, 3,
4), due to current flowing the phase channel and neutral channel; and
generate as output, a differential voltage signal proportional to the difference of
input signals.
According to a second aspect of the present invention, method for neutral missing
tamper detection in an energy meter, the method comprising:
connecting a plurality of source terminals (SI, S2, S3, SN), to a phase terminal
(L) to operate as a phase channel, or operably connecting to a neutral terminal (N)
to operate as a neutral channel;
connecting a plurality of load terminals (LI, L2, L3, LN) to provide electrical
energy to the load;
characterized in that:
connecting a shunt to a phase channel to operate as a current sensor for the phase
channel, and connecting a current transformer, CT, to a neutral channel to operate
as a current sensor for the neutral channel; and

feeding, to a plurality of input terminals (1, 2, 3, 4) of an operational amplifier,
Op-Amp, the current sensor outputs of the phase channel and the current sensor
outputs of the neutral channel;
operating the Op-Amp as a differential Op-Amp, and detecting the difference in
potential at its input terminals (1, 2, 3, 4), due to current flowing the phase
channel and neutral channel, when the energy meter is subjected to neutral
missing tamper; and
generating as output, a differential voltage signal proportional to the difference of
input signals, at an output terminal of the Op-Amp.
Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
The above and other aspects, features and advantages of the embodiments of the present disclosure will be more apparent in the following description taken in conjunction with the accompanying drawings, in which:
Fig. 1A illustrates an exemplary energy meter configuration under normal operation, according to prior art.
Fig. IB illustrates an exemplary energy meter configuration with neutral disconnected, according to prior art.
Fig. 2A and Fig. 2B illustrate exemplary line diagram of the connections of a single-phase and a three-phase energy meter arrangement respectively, according to an embodiment of the present invention.

Fig. 3 illustrates a connection diagram to detect neutral missing tamper in a single-phase energy meter, according to an embodiment of the present invention.
Fig. 4 illustrates a corresponding block diagram connection arrangement to detect neutral missing tamper in a single-phase energy meter, according to an embodiment of the present invention.
Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.
DETAILED DESCRIPTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of various embodiments of the present disclosure as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the various embodiments described herein can be made without departing from the scope and spirit of the present disclosure. In addition, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.
The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the present disclosure. Accordingly, it should be apparent to those skilled in the art that the following description of

various embodiments of the present disclosure is provided for illustration purpose only and not for the purpose of limiting the present disclosure as defined by the appended claims and their equivalents.
It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a component surface" includes reference to one or more of such surfaces.
The terminology used herein is for the purpose of describing particular various embodiments only and is not intended to be limiting of various embodiments. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising" used herein specify the presence of stated features, integers, steps, operations, members, components, and/or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, members, components, and/or groups thereof. Also, Expressions such as "at least one of," when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list.
The present disclosure will now be described more fully with reference to the accompanying drawings, in which various embodiments of the present disclosure are shown. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the various embodiments set forth herein, rather, these various embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the present disclosure. Furthermore, a detailed description of other parts will not be provided not to make the present disclosure unclear. Like reference numerals in the drawings refer to like elements throughout.

The subject invention lies in neutral missing tamper detection in energy meters using an operational amplifier. And it provides elimination of energy defrauding.
According to an embodiment, an energy meter for metering of electrical energy and neutral missing tamper detection, comprises: a plurality of source terminals (SI, S2, S3, SN), wherein each source terminal (SI, S2, S3, SN) is operably connected to a phase terminal (L) to operate as a phase channel, or operably connected to a neutral terminal (N) to operate as a neutral channel, a plurality of load terminals (LI, L2, L3, LN), wherein each load terminal (LI, L2, L3, LN) is operably connected to provide electrical energy to the load. The meter further comprises a shunt operably connected to a phase channel to operate as a current sensor for the phase channel, and a current transformer, CT, operably connected to a neutral channel to operate as a current sensor for the neutral channel; and an operational amplifier, Op-Amp, comprising a plurality of input and output terminals, wherein the current sensor outputs of the phase channel and the current sensor outputs of the neutral channel are fed as input to the plurality of input terminals (1, 2, 3, 4) of the Op-Amp. The Op-Amp is configured to operate as a differential Op-Amp, when the energy meter is subjected to neutral missing tamper, and detect the difference in potential at its input terminals (1, 2, 3, 4), due to current flowing the phase channel and neutral channel; and generate as output, a differential voltage signal proportional to the difference of input signals.
The energy meter further comprises a micro-controller unit, MCU, operably connected to the output terminal of the Op-Amp, and MCU is configured to sense the differential voltage signal of the Op-Amp and monitor energy consumption when the energy meter is subjected to neutral missing tamper.
The number of connections from the source terminals or the load terminals varies for a single-phase energy meter and a three-phase energy meter.

In an exemplary implementation, for a single-phase energy meter, the source terminal (SI) is operably connected to a phase terminal (L) to operate as a phase channel and the source terminal (S2) is operably connected to a neutral terminal (N) to operate as a neutral channel, and for a three-phase energy meter, the source terminals (SI, S2, S3) are operably connected to three different phase terminals R-Y-B (Red-Yellow-Blue) to operate as phase channels, and source terminal (SN) is operably connected to a neutral terminal (N) to operate as a neutral channel. For a three-phase energy meter, the connections are made in a star-delta configuration and the like.
According toa another embodiment, a method for neutral missing tamper detection in an energy meter comprising the method steps of: connecting a plurality of source terminals (SI, S2, S3, SN), to a phase terminal (L) to operate as a phase channel, or operably connecting to a neutral terminal (N) to operate as a neutral channel; and connecting a plurality of load terminals (LI, L2, L3, LN) to provide electrical energy to the load. The method further comprises connecting a shunt to a phase channel to operate as a current sensor for the phase channel, and connecting a current transformer, CT, to a neutral channel to operate as a current sensor for the neutral channel; and feeding, to a plurality of input terminals (1, 2, 3, 4) of an operational amplifier, Op-Amp, the current sensor outputs of the phase channel and the current sensor outputs of the neutral channel; operating the Op-Amp as a differential Op-Amp, and detecting the difference in potential at its input terminals (1, 2, 3, 4), due to current flowing the phase channel and neutral channel, when the energy meter is subjected to neutral missing tamper; and generating as output, a differential voltage signal proportional to the difference of input signals, at an output terminal of the Op-Amp.
The method further comprises connecting the output terminal of the Op-Amp to a micro-controller unit, MCU, of the energy meter, sensing, by the MCU, the differential voltage signal of the Op-Amp and monitoring energy consumption, by the MCU, when the energy meter is subjected to neutral missing tamper.

According to an embodiment, as in Fig. 2A and Fig. 2B, illustrating line diagrams of a single-phase and a three-phase energy meter - a device used for measurement of energy in electrical circuit, where the Phase terminal (L), Neutral terminal (N), Source (S) and Load (L) are connected in a way for normal operation. Energy meter have source and load connections as shown in Fig. 2A and Fig. 2B. Source terminals are connected to the source and load terminals are connected to drive the load.
In an exemplary implementation, the number of connections from the source and load depends on the type of source i.e., if the source or load is of single-phase, the number of connections will be two and if the source or load is three-phase, then the number of connections will be 4/3 for star-delta connection.
In general, Energy meter shall have to provide tamper proof energy monitoring and energy calculation. There are many tampers which meter will see in its real scenario. One among those tampers are Neutral missing. Neutral missing tamper occurs when the neutral is disconnected/not connected from the source side. Whereas during this tamper the load can draw current from source by connecting neutral point of load to earth. The usage of an operational amplifier as a detection mechanism facilitates to tackle Neutral Missing tamper and provides energy monitoring during the tamper.
Fig. 3 describes basic connection diagram of energy meter using shunt as current sensor in Phase Channel and CT as current sensor in Neutral Channel. Both phase channel current sensor output and neutral channel current sensor output or source terminals (neutral and phase) are fed to terminals of an operational amplifier, Op-Amp, i.e., terminals 1, 2, 3, 4 or SI and S2 will be connected to input of Op-Amp as shown in Fig. 4.

The Op-Amp is configured as differential operation amplifier with gain K (where K is gain constant and it can be any value). This differential Op-Amp detects the difference in potential at its input terminals and gives output signal which is proportional to difference of inputs. Initially the circuit is tuned to get zero output i.e., at ideal condition the output of Op-Amp should be zero.
When the energy meter is subjected to neutral missing tamper, the current flowing through either of the channels (phase and neutral) will create a differential voltage and which will be sensed by differential Op-Amp. And the differential Op Amp provides proportionate output voltage. A Micro Controller unit of the energy meter senses the voltage and accordingly monitors energy by utilizing output power of Differential Op-Amp. This facilitates detection of neutral missing tamper and monitoring of energy during neutral missing tamper to eliminate energy defrauding.
Some of the non-limiting advantages of the neutral missing detection through Op-Amp in energy meter are:
1. Used in tariff based/non-tariff-based metering to ensure no energy defrauding.
2. Used for both single-phase and three-phase energy meters.
Although neutral missing detection through Op-Amp in energy meter has been described in language specific to structural features, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific methods or devices described herein. Rather, the specific features are disclosed as examples of implementations of neutral missing detection through Op-Amp in energy meter.

WE CLAIM ;

1. An energy meter for metering of electrical energy and neutral missing
tamper detection, said meter comprising:
a plurality of source terminals (SI, S2, S3, SN), wherein each source terminal (SI, S2, S3, SN) is operably connected to a phase terminal (L) to operate as a phase channel, or operably connected to a neutral terminal (N) to operate as a neutral channel;
a plurality of load terminals (LI, L2, L3, LN), wherein each load terminal (LI, L2, L3, LN) is operably connected to provide electrical energy to the load;
characterized in that:
a shunt operably connected to a phase channel to operate as a current sensor for the phase channel, and a current transformer, CT, operably connected to a neutral channel to operate as a current sensor for the neutral channel; and
an operational amplifier, Op-Amp, comprising a plurality of input and output terminals, wherein the current sensor outputs of the phase channel and the current sensor outputs of the neutral channel are fed as input to the plurality of input terminals (1, 2, 3, 4) of the Op-Amp, and the Op-Amp is configured to:
operate as a differential Op-Amp, when the energy meter is
subjected to neutral missing tamper, and detect the difference in
potential at its input terminals (1, 2, 3, 4), due to current flowing
the phase channel and neutral channel; and
generate as output, a differential voltage signal proportional
to the difference of input signals.
2. The energy meter as claimed in claim 1, wherein the energy meter
comprises a micro-controller unit, MCU, operably connected to the output

terminal of the Op-Amp, and MCU is configured to sense the differential voltage signal of the Op-Amp and monitor energy consumption when the energy meter is subjected to neutral missing tamper.
3. The energy meter as claimed in claim 1, wherein the number of connections from the source terminals or the load terminals varies for a single-phase energy meter and a three-phase energy meter.
4. The energy meter as claimed in claim 1, wherein for a single-phase energy meter, the source terminal (SI) is operably connected to a phase terminal (L) to operate as a phase channel and the source terminal (S2) is operably connected to a neutral terminal (N) to operate as a neutral channel, wherein for three-phase energy meter, the source terminals (SI, S2, S3) are operably connected to three different phase terminals R-Y-B to operate as phase channels, and source terminal (SN) is operably connected to a neutral terminal (N) to operate as a neutral channel.
5. The energy meter as claimed in claim 1, wherein for a three-phase energy meter, the connections are made in a star-delta configuration, and wherein the differential Op-Amp has a gain K, K being a gain constant and having any value.
6. A method for neutral missing tamper detection in an energy meter, the method comprising:
connecting a plurality of source terminals (SI, S2, S3, SN), to a phase terminal (L) to operate as a phase channel, or operably connecting to a neutral terminal (N) to operate as a neutral channel;
connecting a plurality of load terminals (LI, L2, L3, LN) to provide electrical energy to the load;
characterized in that:

connecting a shunt to a phase channel to operate as a current sensor for the phase channel, and connecting a current transformer, CT, to a neutral channel to operate as a current sensor for the neutral channel; and
feeding, to a plurality of input terminals (1, 2, 3, 4) of an operational amplifier, Op-Amp, the current sensor outputs of the phase channel and the current sensor outputs of the neutral channel;
operating the Op-Amp as a differential Op-Amp, and detecting the difference in potential at its input terminals (1, 2, 3, 4), due to current flowing the phase channel and neutral channel, when the energy meter is subjected to neutral missing tamper; and
generating as output, a differential voltage signal proportional to the difference of input signals, at an output terminal of the Op-Amp.
7. The method as claimed in claim 6, wherein the method comprises:
connecting the output terminal of the Op-Amp to a micro-controller unit, MCU, of the energy meter;
sensing, by the MCU, the differential voltage signal of the Op-Amp; and
monitoring energy consumption, by the MCU, when the energy meter is subjected to neutral missing tamper.
8. The method as claimed in claim 6, wherein in the energy meter, the number of connections from the source terminals or the load terminals varies for a single-phase energy meter and a three-phase energy meter.
9. The method as claimed in claim 6, wherein for a single-phase energy meter, connecting the source terminal (SI) to a phase terminal (L) to operate as a phase channel and connecting the source terminal (S2) to a neutral terminal (N) to operate as a neutral channel,
wherein for a three-phase energy meter, connecting the source terminals (SI, S2, S3) to three different phase terminals R-Y-B to operate as phase

channels, and connecting source terminal (SN) to a neutral terminal (N) to operate as a neutral channel.
10. The method as claimed in claim 6, wherein for a three-phase energy meter, the connections are made in a star-delta configuration, and
the differential Op-Amp has a gain K, K being a gain constant and having any value.