CLIAMS:1. A method for detecting earth faults in at least one phase system and displaying the earth faults detected, the method comprising:
detecting at least one electric current signal passing through a circuit breaker;
conditioning the electric current signal detected to generate at least one waveform;
sampling the at least one waveform generated to produce at least one sample value;
obtaining an earth fault current sample by adding the at least one sample value produced;
filtering the earth fault current sample to generate at least one output generated, wherein the at least one output generated is a look up table having at least one value; and
displaying the at least one output generated in the form of a phasor diagram.

2. The method as claimed in claim 1, wherein the electric current signals is detected using at least one air-core sensor.

3. The method as claimed in claim 1, wherein the electric current signals is detected using at least one Rogowski coils.

4. The method as claimed in claim 1, wherein the electric current signals is conditioned using a signal integrator and a gain amplifier.

5. The method as claimed in claim 1, wherein the at least one waveform is sampled using an analog-to-digital converter.

6. The method as claimed in claim 1, wherein the earth fault current sample is a resultant earth fault current sample, wherein the resultant earth fault current sample is calculated every 20 samples.

7. The method as claimed in claim 1, wherein the earth fault current sample is filtered using Finite impulse response (FIR) filter.

8. The method as claimed in claim 1, wherein the at least one value is selected from a group comprising of at least one value for a timer for the required sampling frequency, at least one filter tap, and at least one filter coefficients.

9. A system for detecting earth faults in at least one phase system and displaying the earth faults detected, the system comprising:
a firmware comprising
a detection module configured to detect at least one electric current signal passing through a circuit breaker;
a condition module configured to condition the electric current signal detected to generate at least one waveform using a signal integrator and a gain amplifier;
a sample module configured to sample the at least one waveform generated to produce at least one sample value using an analog-to-digital converter;
a resultant module configured to obtain an earth fault current sample by adding the at least one sample value produced;
an finite impulse response (FIR) filter configured to filter the earth fault current sample to generate at least one output generated, wherein the at least one output generated is a look up table having at least one value; and
a display module configured to display the at least one output generated in the form of a phasor diagram.

10. The system as claimed in claim 9, wherein the at least one value is selected from a group comprising of at least one value for a timer for the required sampling frequency, at least one filter tap, and at least one filter coefficients.

11. The system as claimed in claim 9, wherein the electric current signals is detected using at least one air-core sensor.

12. The system as claimed in claim 9, wherein the electric current signals is detected using at least one Rogowski coils.

13. The system as claimed in claim 9, wherein the earth fault current sample is a resultant earth fault current sample, wherein the resultant earth fault current sample is calculated every 20 samples.
,TagSPECI:TECHNICAL FIELD

The present subject matter described herein, in general relates to a method for detection of an earth fault current in circuit breaker, and more particularly, to the method of determining earth-fault current in a multiphase system and displaying the same on a display on the electronic trip unit of a circuit breaker.

BACKGROUND

The present invention is aimed to make the electronic trip units (ETU) compute the earth fault currents and display the same with a phasor diagram on the display of the circuit breaker. These displayed outputs on the ETU provide the user essential earth fault current related information.

The display further refreshes continuously to see activity, or freeze the display to a particular phasor diagram. The phasor diagram as the output provides a good way to check your meter connections for incorrect phase rotation, Current Transformers (CT) polarity, and other errors.

SUMMARY

This summary is provided to introduce concepts related to systems and methods for determining earth-fault current in a multiphase system and displaying the same on a display on the electronic trip unit of a circuit breaker. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.

In one implementation, a method for detecting earth faults in at least one phase system and displaying the earth faults detected is disclosed. The electric current signal passing through a circuit breaker is detected for conditioning the signal detected in order to generate a waveform. The waveform generated is sampled further to generate at least one sample value. The sample values generated are added to obtain an earth fault current sample which is a resultant earth fault current sample. The resultant earth fault current sample is calculated every 20 samples. The earth fault current sample is filtered to generate at least on output. The output is a look up table storing at least one sample value. The at least one sample value is selected from a group comprising of at least one sample value for a timer for the required sampling frequency, at least one filter tap, and at least one filter coefficients. The output is displayed on the display of the circuit breaker. The display may depict the output in the form of a phasor diagram.

The display may refresh continuously to see activity of the breaker, or freeze the display to a particular phasor diagram. The phasor diagram view is a great way to check your meter connections for incorrect phase rotation, current transformers (CT) polarity, and other errors.

In one implementation, a system for detecting earth faults in at least one phase system and displaying the earth faults detected is disclosed. The system comprises of a firmware. The firmware further comprises of a detection module, a condition module, a sample module, a resultant module, a finite impulse response (FIR) filter, and a display module. The detection module is configured to detect at least one electric current signal passing through a circuit breaker. The signal detected is used by the conditioning module which is configured to condition the electric current signal detected in order to generate at least one waveform using a signal integrator and a gain amplifier. The waveform generated is used by the sampling module which is configured to sample the at least one waveform generated to produce at least one sample value using an analog-to-digital converter. The resultant module is configured to obtain an earth fault current sample by adding the at least one sample value produced. The earth fault current sample is filtered using the finite impulse response (FIR) filter in order to generate at least one output generated, wherein the at least one output generated is a look up table having at least one sample value. The generated output is displayed using the display module.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer like features and components.

Figure 1 illustrates a system 1000 for detecting earth faults in at least one phase system and displaying the earth faults detected is shown, in accordance with an embodiment of the present subject matter.

Figure 2 illustrates a method 2000 for detecting earth faults in at least one phase system and displaying the earth faults detected is shown, in accordance with an embodiment of the present subject matter.

Figure 3 illustrates a resultant phasor diagram is shown, in accordance with an embodiment of the present subject matter.

Figure 4 illustrates a phase difference diagram is shown, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION

Preferred embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail to avoid obscuring the present disclosure in unnecessary detail.

Systems and methods for determining earth-fault current in a multiphase system and displaying the same on a display on the electronic trip unit of a circuit breaker are disclosed. In one implementation, the present invention discloses an Electronic Trip Units (ETU) that computes earth fault current and displays the same with a phasor diagram. These waveforms captured on the ETU provide end user essential earth fault current related information.

The display refreshes continuously to see activity, or freeze the display to a particular phasor diagram. The phasor diagram view is a great way to check your meter connections for incorrect phase rotation, CT polarity, and other errors.

In one implementation, a method for detecting earth faults in at least one phase system and displaying the earth faults detected is disclosed. The electric current signal passing through a circuit breaker is detected for conditioning the signal detected in order to generate a waveform. In one example, the electric current signals are detected using at least one air-core sensor. In another example, the electric current signals are detected using at least one Rogowski coils. The electric current signals may be conditioned using a signal integrator and a gain amplifier.

The waveform generated is sampled further to generate at least one sample value. In one example, the at least one waveform is sampled using an analog-to-digital (ADC) converter. In one example, an inbuilt ADC samples the waveform. The ADC used for this purpose does parallel sampling so as to avoid the scan time delay of a multiplexed system between successive channels. It may be understood by the person skilled in the art that any ADC available in the market may be used for the conversion.

The sample values generated are added to obtain an earth fault current sample which is a resultant earth fault current sample. The resultant earth fault current sample is calculated every 20 samples. In one example, the sample values are added to obtain the resultant earth fault current sample. The Root mean square (RMS) value is calculated every 20 samples. This computation of the Earth fault current is done entirely by the firmware without requiring any cone beam computed tomography (CBCT).

The earth fault current sample is filtered to generate at least on output. In one example, the earth fault current sample is filtered using Finite impulse response (FIR) filter. The Third Harmonic being the most dominant results in erroneous metering. Hence a filter for the same is implemented through firmware. It is an FIR filter with impulse response h and input x, where the output is given by equ. 1.
…….. (equ.1)

The output is a look up table storing at least one sample value. The at least one sample value is selected from a group comprising of at least one sample value for a timer for the required sampling frequency, at least one filter tap, and at least one filter coefficients. The output is displayed on the display of the circuit breaker. The display may depict the output in the form of a phasor diagram. In one example, a software code may be written to accept the coefficients stored in the form of a look-up table. The first value in the look-up table is the value for Timer for the required sampling frequency. The next value is the number of filter taps N and the remaining values are filter coefficients. The filters use the dual on-chip multiply-and-accumulate units to realize the above. The RMS values are then displayed on the TFT-LCD. The amplitude of the phasors is proportional to the metered current value. The phase angle difference is computed by calculating the time interval between the zero crossings of the three phase signals. The resultant phasor diagram is displayed as shown in figure 3.

The display may refresh continuously to see activity of the breaker, or freeze the display to a particular phasor diagram. The phasor diagram view is a great way to check your meter connections for incorrect phase rotation, current transformers (CT) polarity, and other errors.

In one implementation, a system for detecting earth faults in at least one phase system and displaying the earth faults detected is disclosed. The system comprises of a firmware. The firmware further comprises of a detection module, a condition module, a sample module, a resultant module, a finite impulse response (FIR) filter, and a display module. The detection module is configured to detect at least one electric current signal passing through a circuit breaker. In one example, the detection module may be storing the air-core sensors or the Rogowski coils in order to detect the signal may be stored. The signal detected is used by the conditioning module which is configured to condition the electric current signal detected in order to generate at least one waveform using a signal integrator and a gain amplifier. The waveform generated is used by the sampling module which is configured to sample the at least one waveform generated to produce at least one sample value using an analog-to-digital converter. In one example, the at least one sample value is selected from a group comprising of at least one sample value for a timer for the required sampling frequency, at least one filter tap, and at least one filter coefficients.

The resultant module is configured to obtain an earth fault current sample by adding the at least one sample value produced. In one example, the resultant earth fault current sample is calculated every 20 samples. In one example, the sample values are added to obtain the resultant earth fault current sample. The Root mean square (RMS) value is calculated every 20 samples. This computation of the Earth fault current is done entirely by the firmware without requiring any cone beam computed tomography (CBCT).

The earth fault current sample is filtered using the finite impulse response (FIR) filter in order to generate at least one output generated, wherein the at least one output generated is a look up table having at least one sample value. The generated output is displayed using the display module.

While aspects of described system and method for determining earth-fault current in a multiphase system and displaying the same on a display on the electronic trip unit of a circuit breaker may be implemented in any number of different computing systems, environments, and/or configurations, the embodiments are described in the context of the following exemplary system.

Referring now to figure 1, a system 1000 for detecting earth faults in at least one phase system and displaying the earth faults detected is shown, in accordance with an embodiment of the present subject matter.

In an exemplary embodiment of the present invention, the system 1000 comprises the firmware 100. The firmware 100 further comprises of a detection module 102, a condition module 104, a sample module 106, a resultant module 108, a finite impulse response (FIR) filter 110, and a display module 112.

The firmware 100 may be a combination of memory and program code and data stored in it for nay processing or computing. The sensors used for detecting the current flowing through the poles of a circuit breaker are Air-Core sensors or Rogowski coils. In one example, the firmware may be present inside a device. The device may be selected from a group comprising of but not limited to mobile phones, computer peripherals, digital cameras, computers, and the like. Firmware may be available in non-volatile memory devices that may include but not limited to such as ROM, EPROM, or flash memory.
The detection module 102 is configured to detect at least one electric current signal passing through a circuit breaker. The detection module 102 may include at least one air-core sensor and/ or at least one Rogowski coils pre-stored in it. It may be understood by the person skilled in the art that, the coil is an electrical device for measuring high speed current pulses or an alternating current (AC).

In one example, the detection module 102 transmits the electric current signal detected to the condition module 104.

The condition module 104 is configured to receive the electric current signal detected and condition the electric current signal detected to generate at least one waveform using a signal integrator and a gain amplifier. The output of the detection module 102 is ‘conditioned’ using a signal integrator and gain amplifier. In one example the signal may be conditioned to control the analog signal in such a way that it satisfies certain requirements of the next stage for further processing. The signal integrator may be used perform integration of signals may be with respect to time. In one example a “voltage integrator” is a device performing an integration of an electric voltage with respect to time, and also measures a total electric flux. Similarly, a current integrator is a device performing integration of an electric current with respect to time, also measures a total electric charge. The gain amplifiers may be used to measure the ability of an electric circuit that may be an amplifier, in order to increase the amplitude or power of a signal from the input to the output, by adding energy to the signal converted from some power supply. It may be understood by the person skilled in the art that the usage of signal integrator and gain amplifier in the present invention is done as per the standard operational working.

In one example, the condition module 104 transmits the at least one waveform generated to the sample module 106.

The sample module 106 is configured to receive the at least one waveform generated and sample the at least one waveform generated to produce at least one sample value using an analog-to-digital converter. In one example, the sampling is done in order to produce at least one sample value. The sample value may be a value or set of values at a point in time and/or space. Basically, the sampling may be achieved for functions that are varying in space or time or any other dimension, and similar results are obtained in two or more dimensions. It may be understood by the person skilled in the art that the usage of analog-to-digital converter for sampling in the present invention is done as per the standard operational working.

In one embodiment of the present invention, the signal from condition module 104 is transmitted to the microcontroller, where an inbuilt ADC samples the waveform. The ADC used for this purpose may perform parallel sampling so as to avoid the scan time delay of a multiplexed system between successive channels.

In one example, the sample module 106 may transmits the at least one sample value produced to the resultant module 108.

The resultant module 108 is configured to receive the at least one sample value produced and obtain an earth fault current sample by adding the at least one sample value produced. In one example, the sample values obtained from the sample module 106 are added to obtain the resultant earth fault current sample. The resultant earth fault current sample may be obtained from a root mean square also referred to as RMS, which is also sometimes referred to as a quadratic mean. The RMS is an arithmetical measure of the magnitude of a varying quantity. It is especially useful when the variation are positive and negative, e.g., sinusoids. In the present invention, the RMS may be calculated for a series of discrete values or for a continuously varying function. It may be understood by the person skilled in the art that the usage of root mean square in the present invention is done as per the standard operational working.

The RMS value may be calculated every 20 samples. This computation of the Earth fault current is done entirely by the firmware 100 without requiring any core-balance current transformer (CBCT).

In one example, the resultant module 108 transmits the earth fault current sample obtained to the finite impulse response (FIR) filter 110.

The finite impulse response (FIR) filter 110 is configured to receive the earth fault current sample obtained and filter the earth fault current sample to generate at least one output generated, wherein the at least one output generated is a look up table having at least one value. The earth fault current sample is filtered to generate at least on output. In one example, the earth fault current sample is filtered using Finite impulse response (FIR) filter. The Third Harmonic being the most dominant results in erroneous metering. Hence a filter for the same is implemented through firmware. It is an FIR filter with impulse response h and input x, where the output is given by equ. 1.

…….. (equ.1)

The output is a look up table storing at least one sample value. The at least one sample value is selected from a group comprising of at least one sample value for a timer for the required sampling frequency, at least one filter tap, and at least one filter coefficients.

In one example, the finite impulse response (FIR) filter 110 transmits the output generated to the display module 112.

The display module 112 is configured to receive the output and display the at least one output generated. The output is displayed on the display of the circuit breaker. The display may depict the output in the form of a phasor diagram. In one example, a software code may be written to accept the coefficients stored in the form of a look-up table. The first value in the look-up table is the value for Timer for the required sampling frequency. The next value is the number of filter taps N and the remaining values are filter coefficients. The filters use the dual on-chip multiply-and-accumulate units to realize the above. The RMS values are then displayed on the TFT-LCD. The amplitude of the phasors is proportional to the metered current value. The phase angle difference is computed by calculating the time interval between the zero crossings of the three phase signals. The resultant phasor diagram is displayed as shown in figure 3.

The display may refresh continuously to see activity of the breaker, or freeze the display to a particular phasor diagram. The phasor diagram view is a great way to check your meter connections for incorrect phase rotation, current transformers (CT) polarity, and other errors.

Referring now to figure 2, a method 2000 for detecting earth faults in at least one phase system and displaying the earth faults detected is shown, in accordance with an embodiment of the present subject matter. The method 2000 may be described in the general context of computer executable instructions. Generally, computer executable instructions can include routines, programs, objects, components, data structures, procedures, modules, functions, etc., that perform particular functions or implement particular abstract data types. The method 2000 may also be practiced in a firmware where functions are performed by remote processing devices that are linked through a communications network. The firmware 100 may be a combination of memory and program code and data stored in it for nay processing or computing. The sensors used for detecting the current flowing through the poles of a circuit breaker are Air-Core sensors or Rogowski coils. In one example, the firmware may be present inside a device. The device may be selected from a group comprising of but not limited to mobile phones, computer peripherals, digital cameras, computers, and the like. Firmware may be available in non-volatile memory devices that may include but not limited to such as ROM, EPROM, or flash memory.

The order in which the method 2000 is described is not intended to be construed as a limitation, and any number of the described method blocks can be combined in any order to implement the method 2000 or alternate methods. Additionally, individual blocks may be deleted from the method 2000 without departing from the spirit and scope of the subject matter described herein. Furthermore, the method can be implemented in any suitable hardware, software, firmware, or combination thereof. However, for ease of explanation, in the embodiments described below, the method 2000 may be considered to be implemented in the above-described system 1000.

At block 202, at least one electric current signal passing through a circuit breaker is detected. In one example, the sensors used for detecting the current flowing through the poles of a circuit breaker are Air-Core sensors or Rogowski coils. The signals detected are passed on to the block 204.

At block 204, the electric current signal detected is conditioned to generate at least one waveform. In one example, the electric current signals are conditioned using a signal integrator and a gain amplifier. The waveform is passed on to the block 206.

At block 206, the at least one waveform generated is sampled to produce at least one sample value. In one example, the at least one waveform is sampled using an analog-to-digital converter.

At block 208, an earth fault current sample is obtained by adding the at least one sample value produced. In one example, the earth fault current sample is a resultant earth fault current sample, wherein the resultant earth fault current sample is calculated every 20 samples.

At block 210, the earth fault current sample is filtered to generate at least one output generated. In one example, the at least one output generated is a look up table having at least one value. The at least one value is selected from a group comprising of at least one value for a timer for the required sampling frequency, at least one filter tap, and at least one filter coefficients.

At block 212, the at least one output generated is displayed. In one example the output may be displayed on the TFT-LCD.

Referring now to figure 3, a resultant phasor diagram as output is shown, in accordance with an embodiment of the present subject matter.

In one example, the amplitude of the phasors is proportional to the metered current value. The phase angle difference is computed by calculating the time interval between the zero crossings of the three phase signals. The resultant phasor diagram is displayed as shown in figure 3.

Referring now to figure 4, a phase difference diagram is shown, in accordance with an embodiment of the present subject matter.

Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features:

It is one feature of the present invention that, the earth fault is computed entirely using the software and without the requirement of the CBCT.

It is another feature of the invention that, the phase angle of the currents through software is computed without using a zero crossing detectors in hardware as implemented in the prior-art or traditional way.

It is another feature of the invention that, the third harmonic filter is implemented using the software and nullify the dominant harmonic.

It is another feature of the invention that, the invention uses the computation of earth fault using the parallel sampling of the signals, which avoids the errors introduced due to scanning interval between successive channels which could be in microseconds and provide inaccuracy in metering.

It is another feature of the invention that, the phasor diagram is displayed on the electronic trip unit itself without requiring an additional module.

It is still another feature of the invention that, the colored phasor diagrams and provides a user friendly interface for easily identifying the phase with the color.

It is still another feature of the invention that, the phasor diagram refreshes dynamically in real time and can be paused for analysis if required.

It is yet another feature of the invention that, the error in phase sequence and polarity can be identified by the user on observing the phasor diagram on the LCD.

Although implementations for methods and systems for detecting earth faults in at least one phase system and displaying the earth faults detected have been described in language specific to structural features and/or methods, it is to be understood that the appended claims are not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as examples of implementations for detecting earth faults in at least one phase system and displaying the earth faults detected.
It is intended that the disclosure and examples above be considered as exemplary only, with a true scope and spirit of disclosed embodiments being indicated by the following claims.