Claims:1. A method for monitoring system of an electronic trip unit, for use in a circuit breaker (100), said method comprising:
communicating metering data to remote systems (108) for network monitoring;
providing a set of values to differentiate the defined availability-states of a network parameter from its valid values;
storing, using a storing means, breaker (100) settings;
measuring, using a measuring means, current and voltage signals to generate one or more current and voltage value; and
transmitting, from said measuring means, said current and voltage value to said electronic trip unit;
feeding, to a signal conditioning module (104) of said electronic trip unit, said current and voltage signal to generate an output signal, thereby
sampling, using analog to digital convertor (105) in a processor (106) of said electronic trip unit; and
communicating, using a communication interface (107), metering data to remote systems/station (108) for monitoring purpose; and

wherein said method provides real time data on system with minimum possible latency and clarity.

2. The method as claimed in claim 1, wherein the storing means is a non-volatile flash memory (103).

3. The method as claimed in claim 1, wherein measuring means are current sensor (101) and voltage sensor (102).

4. The method as claimed in claim 1, wherein the availability-states also give information about the different interlocks a particular parameter has with some other parameters or settings.

5. The method as claimed in claim 1, wherein said signal conditioning module (104) samples said output signal using a processor (106) in said electronic trip unit.

6. The method as claimed in claim 1, wherein said metering data comprises current per phase, current unbalance per phase, voltage per phase, line voltage, average voltage, voltage unbalance, frequency, power factor, active reactive and apparent power etc.

7. The method as claimed in claim 1, wherein said remote system comprises smartphones and SCADA systems (108).

8. The method as claimed in claim 1, wherein said electronic trip unit is IOT capable and can provide breaker parameters to cloud based systems using communication protocols.

9. The method as claimed in claim 8 wherein said communication protocols comprises Ethernet, Zigbee, Profibus and wifi.

10. The method as claimed in claim 1, wherein said circuit breaker (100), said measuring means, and said electronic trip unit are communicable coupled to each other and configured to transmit and receive data.

11. An electronic trip unit in a circuit breaker for communicating metering data, comprising:

a communication interface (107) for communicating metering data to remote systems/station (108); whereby the communication interface (107) being configured to provide a set of values to differentiate defined availability-states of a network parameter from its valid values;
a storing means for storing breaker (100) settings;
a measuring means for measuring current and voltage signals to generate one or more current and voltage value; and transmitting, from said measuring means, said current and voltage value to said electronic trip unit;

a signal conditioning module (104), using said current and voltage signal to generate an output signal, thereby

an analog to digital convertor (105) in a processor (106) for sampling of said electronic trip unit.

12. The electronic trip unit as claimed in claim 11 wherein the storing means is a non-volatile flash memory (103).

13. The electronic trip unit as claimed in claim 11 wherein measuring means current sensor (101) and voltage sensor (102) are configured to measure the current and voltage signals.

14. The electronic trip unit as claimed in claim 11 wherein said signal conditioning module (104) is configured to sample said output signal using a processor (106) in said electronic trip unit.

15. The electronic trip unit as claimed in claim 11 wherein said remote system/stations comprises smartphones and SCADA systems (108).

16. The electronic trip unit as claimed in claim 11, wherein said electronic trip unit is IOT capable and can provide breaker parameters to cloud based systems using communication protocols.
, Description:TECHNICAL FIELD
The present invention generally relates to a circuit breaker. In particular, the invention relates to electronic trip unit with enhanced reliability.

BACKGROUND AND PRIOR ART
Electronic trip units (ETU) are the brains behind modern day circuit breakers. Primarily ETU reads the current and voltage values sampled by the ADC, calculate per cycle RMS value and issues a trip command if the current/voltage goes above the threshold set by the user. It also computes current, voltage, frequency, energy and power metering parameters and can generate the trip record, alarm record, pickup record etc. whenever the condition occurs. Hence microcontroller/processor based electronic trip units are capable of providing a vast variety of protections such as current, voltage, frequency and power protections. Apart from these basic functionalities, ETU are also IOT capable devices and can provide various breaker parameters such as metering data, trip/event records, breaker settings, breaker position to cloud based systems using communication protocols like Ethernet, Zigbee, Profibus, wifi and so on. Thus, users can monitor the real time status of a circuit breaker on smartphones, SCADA systems and can operate the circuit breaker remotely when required. Hence, it becomes important to provide real time data on network with minimum possible latency and with clarity.
Circuit breakers provide protection from overcurrent, over voltage conditions and are necessarily required to be capable of powering from current flowing through it. Electronic trip units compute various metering parameters such as current per phase, current unbalance per phase, voltage per phase, line voltage, average voltage, voltage unbalance, frequency, power factor, active, reactive and apparent power, etc. Some of these parameters are calculated based upon the configuration settings of circuit breaker and some of the parameters require presence/absence of other metering parameters. For example, phase voltage is calculated with respect to the neutral voltage. So in case of a 3 pole breaker, the neutral pole is not present. Hence the phase voltage cannot be calculated in such case, but line voltage can be calculated. Similarly, the computation of frequency, power factor, energy and power metering parameters depends upon the presence of both current and voltage. In case the current / voltage signal is not present or is below a particular noise/healthy signal threshold which could be required for proper calculation of dependent parameters, such parameters cannot be computed. In all such cases, metering data show default value of 0. But default 0 can be misleading. For example, 0 power factor means that current and voltage signal are out of phase (inductive load) and hence it will provide a wrong indication to the user. One more example, could be presence of current/voltage signal, but below the threshold required for accurate calculation of frequency. Hence frequency cannot be calculated accurately and instead of showing inaccurate value, default 0 is displayed. This again will be confusing for the user as current/voltage signal is present but the frequency will be displayed as 0.
Document DE102014103494A1 discloses methods and systems for continuous calibration of the circuit breaker trip units and measuring. This document talks about calibrating the electronic trip unit during run time. This is specially done for lower current ratings. The document suggests that at lower current values, data metered by the electronic trip nits may not be very accurate and the error margin may also fluctuate. Reason being the changes in accuracy levels of current transformer over time for lower range. The document suggests that apart from the circuit breaker which will be used to make/break currents to the load, another breaker/reference meter will be used. This breaker/ reference meter (known as main unit) will be connected above the circuit breaker and is more accurate as compared to the circuit breaker being used with load. Many circuit breakers can be connected to the main unit. Main unit and circuit breaker connected to the load are also connected to a computing device via communication interfaces. This computing device reads the metered current from both the main unit and the circuit breaker connected to the load. It computes the difference in the current value computed and calculates the calibration factor to be applied to the circuit breaker. This factor is run time applied to the circuit breaker connected to the load. Though the document mentioned above increases the reliability of the system, it additionally requires connection of a main unit which could be a reference meter or another circuit breaker of higher accuracy. It involves additional cost to the system. Also, it doesn’t address the problem where metering data for certain parameters cannot be computed because of the circuit breaker configurations.
Thus, in view of the above mentioned drawbacks, there exists a dire need for improvements in this regard and will be of particular importance to the user who is remotely reading these parameters and taking some decision based upon the data collected. It will help the user to differentiate between fault conditions from those which are due to system setting/ computation related limitations.

OBJECT OF THE INVENTION
An object of the present invention is to provide a method of communicating metering data to remote systems with enhanced reliability.
An object of the present invention is to provide a set of values to differentiate the availability states of a network parameter from its valid values.
Another object of the present invention is to provide a precise information about whether the parameter can be computed, or whether it is in the valid range as per the breaker settings.
Yet another object of the invention is to provide information about the different interlocks a particular parameter has with some other parameters or settings.
These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.

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.
In accordance with the purposes of the present invention in one aspect there is embodied and broadly described an electronic trip unit with enhanced reliability for network monitoring. Basically, it discloses a method of communicating metering data to remote systems with enhanced reliability. Current disclosure differentiates between conditions where metering parameters cannot be computed because of the system/ circuit breaker configuration from the fault conditions.
In one implementation, the method communicates metering data to remote systems for network monitoring.
In one implementation, the method provides a set of values to differentiate the defined availability-states of a network parameter from its valid values
In another implementation, the method uses storing means for storing breaker settings.
In another implementation, the method uses measuring means for measuring current and voltage signals to generate one or more current and voltage value.
In another implementation, the method uses a signal conditioning module of electronic trip unit for feeding current and voltage signal to generate an output signal.
Yet in another implementation, the method uses analog to digital convertor in a processor of said electronic trip unit for sampling.
Yet in one more implementation, the method uses a communication interface for communicating metering data to remote systems for monitoring purpose.

Yet in one more implementation, the invention discloses an electronic trip unit in a circuit breaker for communicating metering data, comprising: a communication interface for communicating metering data to remote systems/station ; a set of values to differentiate the defined availability-states of a network parameter from its valid values; a storing means for storing breaker settings; a measuring means for measuring current and voltage signals to generate one or more current and voltage value; and transmitting, from said measuring means, said current and voltage value to said electronic trip unit; a signal conditioning module , using said current and voltage signal to generate an output signal, thereby an analog to digital convertor in a processor for sampling of said electronic trip unit.

One of the many advantages associated with the present invention is that it differentiates between conditions where metering parameters cannot be computed because of the system/ circuit breaker configuration from the fault conditions. Further, it will help the user to differentiate between fault conditions from those which are due to system setting/computation related limitations.

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 THE ACCOMPANYING DRAWINGS
It is appreciated that the drawings provided in the present disclosure only illustrate application examples of the present disclosure and are therefore not to be construed as limiting its scope. The foregoing disclosure provides additional information with additional specificity and detail with the accompanying drawings, which are listed below for quick reference.
Fig. 1 illustrates a schematic view of the building blocks of the circuit breaker system, in accordance with an embodiment of the present disclosure.
Fig. 2 illustrates the flow diagram of the implementation, in accordance with an embodiment of the present disclosure.
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 OF THE INVENTION
It should be understood at the outset that although illustrative implementations of the present disclosure are illustrated below, the present invention may be implemented using any number of techniques, whether currently known or in existence. The present disclosure should be in no way limited to illustrative implementations, drawings, and techniques, illustrated below, including the exemplary design and implementation illustrated and described herein, but may be modified within the scope of equivalents.
Unless otherwise defined, all terms and especially technical and/or scientific terms, used herein, may be taken to have the same meaning as commonly understood by one having an ordinarily skilled in the art.
Reference is made herein to some “embodiments”. It should be understood that an embodiment is an example of a possible implementation of any features and/or elements presented in the foregoing claims. Some embodiments have been described for the purpose of illuminating one or more potential ways in which the specific features and/or elements of the foregoing claims fulfill the requirements of uniqueness, utility, and non-obviousness.
Fig. 1 illustrates a schematic view of the building blocks of the circuit breaker system with a circuit breaker (100) and the components of the electronic trip unit which includes a signal conditioning module (104), analog-to-digital converter (105), flash memory (103), processor (106), measuring means as a part of the circuit breaker system which comprises of a current sensor (101) and voltage sensor (102). Fig. 1 also shows a communication interface (107) and a remote system/station (108).
In one implementation, the present invention provides a circuit breaker (100) with an electronic trip unit as a part of its construction which further consists of its own components for the purpose of communicating metering data of the circuit breaker system to the remote systems (108).
In one implementation, present invention provides current sensor (101) and voltage sensor (102) measuring means for measuring current and voltage signals for further transmitting the current and voltage value to the electronic trip unit for feeding them to the signal conditioning module (104) for generating an output signal for sampling, using analog to digital convertor (105) in a processor (106) of said electronic trip unit.
In another implementation, present invention provides a non-volatile flash memory (103) for storing the breaker settings.
In one implementation, there is provided a communication interface (107) in communication with the remote systems/station (108) for Communicating, using a communication interface (107), metering data to remote systems for monitoring purpose of the user so that the user can take critical decisions based on the network parameters and differentiate between fault conditions from those which are due to system settings/ computation limitations.
The present disclosure differentiates between conditions where metering parameters cannot be computed because of the system/circuit breaker configuration from the fault conditions. For example, for 3 pole circuit breaker phase voltages cannot be computed. Similarly, for phase sequence computation, voltage should be present in all three phases above a certain threshold. If voltage is present in 2 phases, but in 3rd phase it is below the healthy voltage threshold then phase sequence cannot be computed. In such cases usually metering data shows the default value of 0. If the parameter contains 0 values, it would mean that either parameter was not computed or ETU computed a wrong value. This information will be misleading to the user. One more example could be presence of current/voltage signal, but below the threshold required for accurate calculation of frequency. Hence frequency cannot be calculated accurately and instead of showing inaccurate value, default 0 is displayed. This again will be confusing for the user as current/voltage signal is present but the frequency will be displayed as 0. Hence there exists a need for improvements in this regard and will be of particular importance for network monitoring at remote station where critical decisions need to be taken based on the network parameters. It will help the user to differentiate between fault conditions from those which are due to system setting/ computation related limitations.
Modern day circuit breakers employ microcontroller/processor based trip units and are capable of providing a wide variety of protections such as current, voltage, frequency, power etc. Electronic trip units compute various metering parameters such as current per phase, current unbalance per phase, voltage per phase, line voltage, average voltage, voltage unbalance, frequency, power factor, active, reactive and apparent power etc. Some of these parameters are calculated based upon the configuration settings of the circuit breaker and some of the parameters require presence/absence of other metering parameters. If it is found that a particular metering parameter cannot be computed because of settings of circuit breaker or because of current/voltage being below the healthy threshold value, then suitable indication is provided. This suitable indication can be called as Availability-states of the parameter. Availability-states will provide the information on whether a particular parameter can be computed, or whether it is in the valid range as per the breaker settings. As per the present disclosure, three availability states are defined, namely VALID_DATA, DATA_OUT_OF_RANGE, DATA_NOT_COMPUTED. VALID_DATA state will hold the metered value of the parameter and will be in the range as per specifications. DATA_OUT_OF_RANGE will hold a value which is beyond the specified range of the parameters. This would mean that though the parameter was computed it is not in the predefined range. DATA_NOT_COMPUTED will hold a value which will specify that a particular parameter couldn’t be computed because of the circuit breaker settings. With this implementation, the above three states can be differentiated by the user and hence he will not be misled by incorrect information. ETU are also IoT capable devices and can provide various breaker parameters such as metering data, trip/event records, breaker settings, breaker position in cloud based systems using communication protocols like Ethernet, Zigbee, Profibus, wifi and so on. Thus, users can monitor the real time status of a circuit breaker on smartphones, SCADA systems and can operate the circuit breaker remotely when required
Fig. 2 illustrates the flow diagram of the implementation. Referring to fig. 2 the breaker settings are stored in the non-volatile memory of the controller and read at power-up of ETU (Electronic Trip Unit). Whenever the metering data is to be computed, it is first checked if the particular metering parameter is valid with respect to the breaker settings. For example, for 3 pole breaker phase voltage is invalid data and cannot be computed. Line voltage in this case is a valid data and can be computed by the ETU. So if the metering parameter is invalid, then the availability state is modified to DATA_NOT_COMPUTED value. If the metering parameter is valid, then it is checked if it requires the current/voltage to be above a healthy threshold (TH1) value. This healthy threshold value is usually higher than the noise threshold. Noise threshold is used to detect the presence/absence of current/voltage signal. Healthy threshold (TH1) signifies the minimum current/voltage level which is required for accurate calculation of parameters (such as frequency) which are computed from current/voltage signal. So if the current / voltage is above the noise threshold but below TH1, then the availability state of the metering parameter is modified to DATA_NOT_COMPUTED value. If threshold TH1 check is satisfied, then the parameter is calculated. A range check for the parameter is performed. If parameter’s computed value is in the valid range, then availability state holds VALID_DATA. Otherwise, availability state is modified to DATA_OUT_OF_RANGE.
The above logic can be extended to trip records and oscillography which captures a wide variety of metering data, thus helping the user to diagnose the reason behind fault. In this way reliability can be added in network monitoring systems at a remote station where critical decisions need to be taken based on the network parameters. Present invention suggests that any metering parameter can be reliably decoded based upon its availability state. Availability-states will provide the information on whether a particular parameter can be computed, or whether it is in the valid range as per the breaker settings. It can hold a value apart from the default value 0.
Some of the benefits of the present invention, considered to be noteworthy are mentioned below:

[1]. Invention suggests providing a set of values to differentiate the availability-states of a network parameter from its valid values.

[2]. Availability-states of a network parameter give precise information about whether the parameter can be computed, or whether it is in the valid range as per the breaker settings. The states also give information about the different interlocks a particular parameter has with some other parameters or settings.

[3]. The possible availability-state value of a network parameter is not a part of its valid range which is specified for its monitoring. This avoids any clash or possibility of misleading information reaching the user.

[4]. The availability-state values for different network parameters are published along the memory map of the communication system. It helps for user to develop a custom-SCADA system which can be used for reliable network monitoring.