Claims:1. A system (100) for neutral isolation in an electronic trip unit (ETU) comprising an internal star point neutral operatively coupled to an external star point neutral, the system (100) comprising:
an operational amplifier (Op-Amp) (102) comprising an input side having a positive input terminal (102-3) and a negative input terminal (102-2), and an output terminal (102-1), wherein the internal star point neutral of the ETU is electrically coupled to the output terminal of the Op-Amp (102-1) such that an internal reference voltage of the internal star point neutral corresponds to a voltage generated at the output terminal of the Op-Amp ( 102-1); and
wherein the external star point neutral is configured with the input side of the Op-Amp such that the internal reference voltage of the internal star point neutral changes based on a displacement in the external star point neutral due to unbalance in phase voltages associated with the external star point neutral.
2. The system (100) as claimed in claim 1, wherein the external star point neutral is electrically coupled to the negative input terminal of the Op-Amp (102-2), and wherein the positive input terminal of the Op-Amp (102-3) is electrically coupled to a voltage source through a first resistor R3, and configured to facilitate in providing a voltage equal to the internal reference voltage at the output terminal of the Op-Amp (102-1).
3. The system (100) as claimed in claim 2, wherein the system (100) comprises a voltage divider circuit operatively coupled with each phase of the external star point neutral, and configured to step-down phase voltages associated with the external star point neutral, and wherein the voltage divider circuit comprises a second resistor R2 and a third resistor R3.
4. The system as claimed in claim 3, wherein phases of the external star point neutral are electrically configured with the Op-Amp using a feedback resistor between the negative input terminal (102-2) and output terminal of the Op-Amp (102-1).
5. The system (100) as claimed in claim 1, wherein the external star point neutral, and the internal star point neutral are configured with the Op-Amp (102) such that the external star point neutral and the internal star point neutral have same voltage, which facilitates in neutral isolation between the external star point neutral and the internal star point neutral.
6. The system (100) as claimed in claim 1, wherein the change in the internal reference voltage of the internal star point neutral based on the displacement in the external star point neutral due to unbalance in the phase voltages associated with the external star point facilitates measurement of the phase voltages using one or more voltage measuring devices.
7. The system (100) as claimed in claim 1, wherein the change in the internal reference voltage of the internal star point neutral based on the displacement in the external star point neutral due to unbalance in the phase voltages associated with the external star point shifts the internal star point neutral based on the displacement in the external star point neutral.
8. The system (100) as claimed in claim 1, wherein the ETU is configured with a multi transformer-based substation.
9. The system (100) as claimed in claim 1, wherein the voltage generated at the output terminal of the Op-Amp (102-1) and the internal reference voltages provided at the internal star point neutral is 1.5 Volts.

, Description:TECHNICAL FIELD
[0001] The present disclosure relates generally to field of electrical power distribution and air circuit breakerand protection relays. More particularly, the present disclosure provides a system for neutral isolation in an electronic trip unit (ETU) for multi transformer based substation, and the likes.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] In existing air circuit breaker (ACB) MTX 3.5 & onwards protection releases an add-on metering module is connected to release for sensing, metering and protection of voltage based parameters. The metering module connects to primary of system and senses primary input voltage and signal is being pass through signal condition block before going to ADC channel of the controller. Therefore, for metering and voltage based protection, it is required to have a local neutral in the system which can adjust in star point created locally in the system according to external unbalance in the system. In the existing units local neutral is being created from external neutral of the system without having any external isolation. Due to lack of isolation whenever a potential is created between the neutral and earth of the system, the same potential used to develop across the different grounds of the controller due to which controller will burn.
[0004] UW-MTX 3.5EC onwards protection releases offers current protection and advanced protection like voltage, energy, power, frequency and power factor to the system.
[0005] UW-MTX 3.5EC are self and aux powered release. It senses the primary current with the help of Rogowski coil and offers the current protection based on that. However for all other advanced protection an add-on metering module is required which sense the input primary voltage and condition the signal for the ADC of the controller.
[0006] According to a cited reference CN201298732Y with title “An intelligent demarcation grounding protection apparatus based on ordinary column circuit breaker”, where the reference includes compensation technique with digital relay connected to the column circuit breaker. However, does not include neutral isolation techniques. Another cited reference US4264960Awith title “System for controlling power distribution to customer loads”, where the referenceUS4264960A discloses about load shading techniques through micro-controller however the isolation between different grounds internal to electrical trip units is not disclosed.Another cited reference EP0023254A2 with title “Method and apparatus for controlling power distribution of an electric utility”, where the referenceEP0023254A2 discuss about the load shading technique where user can control the load through memory address in the controller however the reference does not discuss about the isolation techniques used for isolating primary and secondary ground.According to a cited reference KR100760331B1 with title “High speed automatic circuit breaker for protection”, where the reference KR100760331B1 discloses working principle of circuit breaker and also mechanical design done in such a way to reduce open time of the breaker however the isolation techniques for isolating internal and external ground is not disclosed.
[0007] There is a need to overcome above mentioned problems stated in prior art by bringing solution which provides isolation between different grounds of the system with controller ground. The solution provides neutral isolation of the system from local ground. Also, the solution facilitates in displacing reference voltage of the system according to the unbalance in the system.

OBJECTS OF THE PRESENT DISCLOSURE
[0008] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[0009] It is an object of the present disclosure to provide a system that contributes in low cost isolation between neutral and local ground with help of operational amplifier and facilitates in prevention from electrical losses.
[0010] It is an object of the present disclosure to provide a system that shifts the internal star point neutral based on the displacement in the external star point neutral due to unbalance in phase voltages.
[0011] It is an object of the present disclosure to provide a system that changes the internal reference voltage of the internal star point neutral based on the displacement in the external star point neutral due to unbalance in the phase voltages associated with the external star point, thereby facilitating measurement of the phase voltages using one or more voltage measuring devices.
[0012] It is an object of the present disclosure to provide a system that can withstand high impulse as there is no leakage in the system because of the absence of galvanic isolation.
[0013] It is an object of the present disclosure to provide a system that gives a robust solution which can be easily implemented in other products which need isolated neutral.
[0014] It is an object of the present disclosure to provide a system where neutral internal to electronic trip unit is completely isolated from the external neutral of electronic trip unit
[0015] It is an object of the present disclosure to provide a facilitates in promoting electronic trip unit releases in market with added features to meet market competition.
[0016] It is an object of the present disclosure to provide a system that helps in avoiding mis happening caused due to sudden spark, thermal overload, short circuit or ground fault by isolating primary and secondary ground.

SUMMARY
[0017] The present disclosure relates generally to field of electrical power distribution and air circuit breakerand protection relays. More particularly, the present disclosure provides a system for neutral isolation in an electronic trip unit (ETU) for multi transformer based substation, and the likes.
[0018] An aspect of the present disclosure pertains to a system for neutral isolation in an electronic trip unit (ETU) including an internal star point neutral operatively coupled to an external star point neutral. The system may include an operational amplifier (Op-Amp) including an input side having a positive input terminal and a negative input terminal, and an output terminal. The internal star point neutral of the ETU may be electrically coupled to the output terminal of the Op-Amp such that an internal reference voltage of the internal star point neutral may corresponds to a voltage generated at the output terminal of the Op-Amp. The external star point neutral may be configured with the input side of the Op-Amp such that the internal reference voltage of the internal star point neutral may change based on a displacement in the external star point neutral due to unbalance in phase voltages associated with the external star point neutral.
[0019] In an aspect, the external star point neutral may be electrically coupled to the negative input terminal of the Op-Amp, and where the positive input terminal of the Op-Amp may be electrically coupled to a voltage source through a first resistor, and configured to facilitate in providing a voltage equal to the internal reference voltage at the output terminal of the Op-Amp.
[0020] In an aspect, the system may include a voltage divider circuit operatively coupled with each phase of the external star point neutral, and configured to step-down phase voltages associated with the external star point neutral, and where the voltage divider circuit may include a second resistor and a third resistor.
[0021] In an aspect, the phases of the external star point neutral may be electrically configured with the Op-Amp using a feedback resistor between the negative input terminal and output terminal of the Op-Amp.
[0022] In an aspect, the external star point neutral, and the internal star point neutral may be configured with the Op-Amp such that the external star point neutral and the internal star point neutral have same voltage, which facilitates in neutral isolation between the external star point neutral and the internal star point neutral.
[0023] In an aspect, the change in the internal reference voltage of the internal star point neutral based on the displacement in the external star point neutral due to unbalance in the phase voltages associated with the external star point may facilitate measurement of the phase voltages using one or more voltage measuring devices.
[0024] In an aspect, the change in the internal reference voltage of the internal star point neutral based on the displacement in the external star point neutral due to unbalance in the phase voltages associated with the external star point may shift the internal star point neutral based on the displacement in the external star point neutral.
[0025] In an aspect, the ETU may be configured with a multi transformer-based substation.
[0026] In an aspect, the voltage generated at the output terminal of the Op-Amp and the internal reference voltages provided at the internal star point neutral may be1.5 Volts.

BRIEF DESCRIPTION OF THE DRAWINGS
[0027] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0028] The diagrams are for illustration only, which thus is not a limitation of the present disclosure, and wherein:
[0029] FIG. 1A illustrates a proposed circuit diagram of system for neutral isolation in electronic trip unit (ETU), in accordance with an embodiment of the present disclosure.
[0030] FIG. 1B illustrates an exemplary view of circuit diagram of system for neutral isolation in electronic trip unit (ETU), in accordance with an embodiment of the present disclosure.
[0031] FIG. 2 illustrates a block diagram of air breaker with voltage module, in accordance with an embodiment of the present disclosure.

DETAIL DESCRIPTION
[0032] In the following description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. It will be apparent to one skilled in the art that embodiments of the present invention may be practiced without some of these specific details.
[0033] The present disclosure relates generally to field of electrical power distribution and air circuit breakerand protection relays. More particularly, the present disclosure provides a system for neutral isolation in an electronic trip unit (ETU) for multi transformer based substation, and the likes.
[0034] FIG. 1A illustrates a proposed circuit diagram of system for neutral isolation in electronic trip unit (ETU), in accordance with an embodiment of the present disclosure.
[0035] As illustrated in FIG. 1, the proposed system 100(also referred to as system 100, herein) can include an internal star point neutral and an external star point neutral, where the internal star point neutral can be operatively coupled to the external point neutral. The system 100 can facilitate in neutral isolation in an electronic trip unit (ETU). The system 100 can include an operational amplifier (Op-Amp) 102, where the Op-Amp 102can include an input side with positive input terminal 102-3 and negative input terminal 102-2 as inverting input and a non inverting input respectively. The Op-Amp can include an output terminal 102-1, and dual supply like positive supply 102-11 and a negative supply 102-4. The internal star point neutral of ETU can be electrically coupled to the output terminal of the Op-Amp 102such that that an internal reference voltage of the internal star point neutral corresponds to a voltage generated at the output terminal of the Op-Amp.
[0036] In an embodiment, the external star point neutral can be configured with the input side of the Op-Amp such that the internal reference voltage of the internal star point neutral can change based on a displacement in the external star point neutral due to unbalance in phase voltages associated with the external star point neutral. In another embodiment, the external star point neutral can be electrically coupled to the negative input terminal of the Op-Amp 102-2, and the positive input terminal of the Op-Amp 102- 3 can be electrically coupled to a voltage source through a first resistor R3, and can be configured to facilitate in providing a voltage equal to the internal reference voltage at the output terminal of the Op-Amp 102-1.
[0037] In an embodiment, the system 100 can include a voltage divider circuit operatively coupled with each phase of the external star point neutral, and configured to step-down phase voltages associated with the external star point neutral, and where the voltage divider circuit can include a second resistor R2 and a third resistor R1.In an illustrative embodiment, the each phase can voltages Vr, Vy and Vb, respectively. In another illustrative embodiment, the first resistor R3, the second resistor R2, the third resistor R1 can include predetermined values of resistance.
[0038] In an embodiment, phases of the external star point neutral can be electrically configured with the Op-Amp using a feedback resistor between the negative input terminal 102-2 of the Op-Amp and output terminal of the Op-Amp 102-1. In another embodiment, the external star point neutral, and the internal star point neutral can be configured with the Op-Amp such that the external star point neutral and the internal star point neutral can have same voltage, which facilitates in neutral isolation between the external star point neutral and the internal star point neutral. In yet another embodiment, change in the internal reference voltage of the internal star point neutral based on the displacement in the external star point neutral due to unbalance in the phase voltages associated with the external star point can facilitate measurement of the phase voltages using one or more voltage measuring devices.
[0039] In an illustrative embodiment, the internal reference voltage can include predetermined limit of 1.5 voltages, where the internal star point neutral of the ETU can be configured with the internal reference voltage through the output terminal of Op-Amp 102-1. In another illustrative embodiment, the input of the 0p-Amp can be configured such that when the external star point neutral displaces because of the unbalance in the phase voltages, the Op-Amp input can feedback the external star point neutral displacement and can change the internal reference voltage according to the unbalance caused in the phase voltages and facilitates on measuring the phase voltages accurately and efficiently.
[0040] In an illustrative embodiment, each phase of the external star point neutral can be step down with help of voltage divider circuit, where the voltage divider circuit can include the second resistor R2 and the third resistor R1. In another illustrative embodiment, the external star point neutral can route to the Op-Amp input to provide a predetermined output of 1.5 voltages at the output of the Op-Amp 102-1. The Op-Amp output 102-1 can be connected to the external star point neutral of the ETU.
[0041] In an embodiment, the change in the internal reference voltage of the internal star point neutral based on the displacement in the external star point neutral due to unbalance in the phase voltages associated with the external star point shifts the internal star point neutral based on the displacement in the external star point neutral.
[0042] In an illustrative embodiment, the internal star point neutral operatively coupled with the external star point neutral can facilitate in accurate phase voltage measurement. In another illustrative embodiment, the internal star point neutral displacement can be done by changing the internal reference voltage according to the unbalance of the some reference voltage and the reference voltage will changes as per the unbalance in the phase voltage. In yet another illustrative embodiment, the Op-Amp 102 can facilitate in isolating the internal star point neutral and the external star point neutral and displacing the internal reference voltage according to the unbalance in the phase voltage.
[0043] In an illustrative embodiment, the ETU can be configured with a multi transformer-based substation, and the likes. In another illustrative embodiment, the voltage generated at the output terminal of the Op-Amp 102-1and the internal reference voltages provided at the internal star point neutral can be1.5 Volt.
[0044] FIG. 1B illustrates an exemplary view of circuit diagram of system for neutral isolation in electronic trip unit (ETU), in accordance with an embodiment of the present disclosure.
[0045] As illustrated in FIG. 1B, the system 100 can include an internal neutral star point and an external neutral star point for neutral isolation in electronic trip unit (ETU). The system 100 can include an operational amplifier (Op-Amp) 102 including an input side having a positive input terminal 102-3 and a negative input terminal 102-2, and an output terminal 102-1.The internal star point neutral of the ETU can be electrically coupled to the output terminal of the Op-Amp 102-1such that an internal reference voltage VREF=1.5 volt of the internal star point neutral corresponds to a voltage generated at the output terminal of the Op-Amp 102-1.
[0046] In an embodiment, the external star point neutral can be electrically coupled to the negative input terminal of the Op-Amp 102-1, and where the positive input terminal of the Op-Amp 102-3 can be electrically coupled to a voltage source through a first resistor R3, and configured to facilitate in providing a voltage equal to the internal reference voltage VREF at the output terminal of the Op-Amp 102-1. In another embodiment, the system 100 can include a voltage divider circuit operatively coupled with each phase of the external star point neutral, and configured to step-down phase voltages associated with the external star point neutral, and where the voltage divider circuit can include a second resistor R2and a third resistor R3.
[0047] In an illustrative embodiment, the first resistor R1, the second resistor R2, and the third resistor R3 can include predetermined values of resistances where R1 can include 10 K ohm, R2 can include 6.2 K ohm and R3 can include 1.5 K ohm respectively. In another illustrative embodiment, the system 100 can include a power source with an inductor having predetermined value of resistance 600 R at frequency 100 megahertz along with capacitors C1 and C2 where the C1 can include predetermined limit of 0.1 micro Farad and C2 can include predetermined limit of 1 micro Farad with 6.3 voltages.
[0048] FIG. 2 illustrates a block diagram of air breaker with voltage module, in accordance with an embodiment of the present disclosure.
[0049] As illustrated in FIG. 2, the block diagram can include three phase input supply with neutral 202, a breaker 204, a voltage module with neutral isolation 206, flux shift device (FSD) 208, electronic trip unit (ETU) 210.In an illustrative embodiment, the ETU 210 can include a processing unit, where the processing unit can be configured to measure current flowing through the breaker 204 and can generate a set of trip signals on time of thermal overload. In another illustrative embodiment, when three phase input supply with neutral is applied to a breaker 204 such that fault occurs on any part of a system like multi transformer based substation, trip coil associated with the breaker 204 gets energized and circuit of the breaker opens. The breaker can generate a set of electrical signals and transfer the set of electrical signals to a processing unit of the ETU. The processing unit of the ETU can generate and transmit the set of trip signals to the FSD 208.
[0050] In an illustrative embodiment, the voltage module with neutral isolation 206 can be configured to receive three phase input supply with neutral and transmit current to the ETU 210, such that the when the current exceeds a predetermined limit, the processing unit of the ETU can generate and transmit the set of trip signals to the FSD 208, which facilitates tripping of the breaker 204.

ADVANTAGES OF THE PRESENT DISCLOSURE
[0051] The present disclosure provides a system that contributes in low cost isolation between neutral and local ground with help of operational amplifier and facilitates in prevention from electrical losses.
[0052] The present disclosure provides a system that shifts the internal star point neutral based on the displacement in the external star point neutral due to unbalance in phase voltages.
[0053] The present disclosure provides a system that changes the internal reference voltage of the internal star point neutral based on the displacement in the external star point neutral due to unbalance in the phase voltages associated with the external star point, thereby facilitating measurement of the phase voltages using one or more voltage measuring devices
[0054] The present disclosure provides a system that can withstand high impulse as there is no leakage in the system because of the absence of galvanic isolation.
[0055] The present disclosure provides a system that gives a robust solution which can be easily implemented in other products which need isolated neutral.
[0056] The present disclosure provides a system where neutral internal to electronic trip unit is completely isolated from the external electronic trip unit
[0057] The present disclosure provides a system which facilitates in promoting electronic trip unit releases in market with added features to meet market competition.
[0058] The present disclosure provides a system that helps in avoiding mis happening caused due to sudden spark, thermal overload, short circuit or ground fault by isolating primary and secondary ground.
[0059] The present disclosure provides a system that aids in displacing reference voltage of the system according to unbalance in the system with help of operational amplifier.