Description:TECHNICAL FIELD
[0001] The present disclosure relates, in general, to circuit breakers, and more specifically, relates to a system and method of providing short-circuit protection in low voltage (LV) switchgear through intelligent electronic devices.

BACKGROUND
[0002] Circuit breakers are used for the protection of the power system from electrical faults. ACBs are upstream devices in the power system and are followed by MCCBs which are lower rating devices used downstream for power system protection. In abnormal conditions, the circuit breaker’s spring mechanism operates based on the current setting and its contacts open to break the fault current flowing through the system.
[0003] Modern-day circuit breakers come along with electronic trip units that are capable of sensing and calculating various line parameters such as current/voltage/power/frequency etc., and providing a wide variety of protection against faults such as overload, short-circuit, overvoltage, undervoltage, over frequency, under frequency, over temperature, earth leakage etc. Protections such as long-time overcurrent are used to protect cables, busbar, busbar trunking systems etc. against overload conditions. These are inverse time curve-based protections where, as the fault current increases trip time reduces. Short-time overcurrent protection helps to protect equipment against phase-to phase, phase-to-neutral and phase-to-ground short circuits along with selectivity. Short time overcurrent protections can be fixed delay-based or inverse time curve-based. Instantaneous protection helps to protect equipment against phase-to-phase, phase-to-neutral and phase-to-ground short circuits. It trips without additional time delay as soon as the setting current is exceeded. The user has the flexibility to set the threshold of various protections based upon load connected, coordination and selectivity to be achieved and the presence of harmonics in the system. Users can also set nominal current value using a hard/soft rating plug.
[0004] Apart from basic protections, certain protections are used to protect circuit breakers and electronic trip units from over-temperature or over-current conditions. These are internal protections and are not settable by the user. One such protection is making current release (MCR) in which the breaker closes onto the short-circuit fault after the breaker had previously opened due to run time short-circuit fault in the system. In case of a run time fault in the system, the breaker is supposed to withstand the fault till the time delay set by the user to maintain selectivity and coordination. This is also known as “O or Open Shot”. Post “Open Shot” if the breaker closes on to short circuit fault current which is near/beyond the short circuit withstand capability of the breaker within a certain time frame (referred here as TDelay_Fault_Reocurrence), then ETU should sense and trip the breaker with 1 cycle time. This is because when the fault current is near/beyond the short circuit withstand capability of the breaker, magnetic repulsion of contacts takes place. Though this phenomenon helps in clearing higher-order faults, sometimes it may lead to welding of the breaker contacts due to frequent chattering before the complete opening of breaker. This leads to both system and breaker damage. Thus, in such a condition it becomes important that the electronic trip unit senses the fault and issues a trip command within 1 cycle of fault occurring. One more scenario could be that after the breaker tripping, the breaker was turned ON without current flowing through it. After some time, the current is passed through the system. Since in this case breaker is not closing on to the fault, the breaker needs to carry the fault till withstand time or delay set by the user. Thus, the electronic trip unit needs to differentiate between runtime fault, closing on fault and fault occurring after breaker was turned ON without current.
[0005] As per IEC 60947-2, the electronic trip unit needs to be powered up from the current carried by the breaker and the auxiliary supply is not mandatory. In case of a fault condition, the electronic trip unit issues a trip command activating a flux shifter device which in turn trips the circuit breaker. Once the circuit breaker trips and the fault is cleared, the power to the self-powered electronic trip unit is cut off. Thus, if the subsequent fault occurs during breaker closing, the time which the electronic trip unit needs for power up is also added in the total tripping time. In the presence of external auxiliary power, even after the circuit breaker trips the power supply to the trip unit is maintained. As mentioned earlier, the trip unit also needs to detect the previous breaker position in order to differentiate between different types of faults and issue trip commands based upon the condition detected.
[0006] However, existing technologies known in the art, the detection of breaker closing on fault within one cycle is limited to instances where an external auxiliary supply is present, rendering the algorithms ineffective when the electronic trip unit is powered solely through the current carried by the breaker. Also, it does not differentiate between Breaker was turned ON with or without Fault current. This deficiency hinders the accurate identification of fault levels and timely response.
[0007] Therefore, it is desired to overcome the drawbacks, shortcomings, and limitations associated with existing solutions, and develop a means to solve the challenge of detecting and differentiating between different fault scenarios based on the previous and present breaker status, previous fault history, and making decisions within one cycle of power-up to ensure quick fault clearance and prevent system damage.

OBJECTS OF THE PRESENT DISCLOSURE
[0008] An object of the present disclosure relates, in general, to circuit breakers, and more specifically, relates to a system and method of providing short-circuit protection in low voltage (LV) switchgear through intelligent electronic devices.
[0009] Another object of the present disclosure is to provide a system where the electronic trip unit (ETU) is configured to promptly sense and trip the circuit breaker within one electrical cycle following the closing of the breaker onto a short-circuit fault shortly after opening due to a runtime fault.
[0010] Another object of the present disclosure is to provide a system that ensures rapid detection and response to immediate short-circuit faults, minimizing downtime and potential damage.
[0011] Another object of the present disclosure is to provide a system that prevents the welding of contacts, preserving the breaker’s functionality and longevity.
[0012] Another object of the present disclosure is to provide a system that reduces the risk of damage to the breaker and connected equipment, ensuring long-term performance.
[0013] Yet another object of the present disclosure is to provide a system that swiftly address faults enhances the overall reliability and efficiency of the electrical system.

SUMMARY
[0014] The present disclosure relates in general, to circuit breakers, and more specifically, relates to a system and method of providing short-circuit protection in low voltage (LV) switchgear through intelligent electronic devices. The main objective of the present disclosure is to overcome the drawbacks, limitations, and shortcomings of the existing system and solution, by providing circuit breaker equipped with an electronic trip unit (ETU) that distinguishes between breaker closing on fault, run-time fault, and faults occurring after the breaker has been turned ON without current, by assessing transition status of the breaker, previous status of the breaker. The ETU makes decisions to either withstand the fault for a user-set delay time or initiate an immediate trip within one cycle, thereby enhancing the breaker's ability to respond effectively to various fault scenarios.
[0015] The present disclosure relates to a system for monitoring a circuit breaker, the system includes an electronic trip unit (ETU) configured to determine a set of parameters for evaluating status of the circuit breaker and detecting making current release (MCR), the set of parameters pertain to transition status of the circuit breaker, previous status of the circuit breaker and present status of the circuit breaker. The electronic trip unit is configured to determine transition status of the circuit breaker, indicating the transition from OFF to ON state through a high pulse during hold time for position change status. Determine the previous status of the circuit breaker by storing the previous status of the circuit breaker for a delay in fault reoccurrence time and determine the present status of the circuit breaker by evaluating runtime position of the circuit breaker, collectively distinguishing among the circuit breaker closing on fault, run-time fault, and faults occurring subsequent to the circuit breaker being turned ON without current. The ETU enable rapid fault detection response, by ensuring the ETU senses the fault and determines to either withstand the fault for a user-set delay time or initiate an immediate trip within one cycle of fault occurrence.
[0016] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The following drawings form part of the present specification and are included to further illustrate aspects of the present disclosure. The disclosure may be better understood by reference to the drawings in combination with the detailed description of the specific embodiments presented herein.
[0018] FIG. 1 illustrates an exemplary block diagram of the circuit breaker, in accordance with an embodiment of the present disclosure.
[0019] FIG. 2A illustrates an exemplary circuit diagram for latching breaker position transition status, in accordance with an embodiment of the present disclosure.
[0020] FIG. 2B illustrates an exemplary circuit diagram for latching previous breaker status, in accordance with an embodiment of the present disclosure.
[0021] FIG. 2C illustrates an exemplary circuit diagram for reading present breaker status, in accordance with an embodiment of the present disclosure.
[0022] FIG. 3 illustrates an exemplary flow chart of a method for monitoring a circuit breaker, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0023] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. If the specification states a component or feature “may”, “can”, “could”, or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[0024] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0025] The present disclosure relates to a system for monitoring a circuit breaker that incorporates an electronic trip unit (ETU) configured to determine a set of parameters for evaluating status of the circuit breaker and detecting making current release (MCR), the set of parameters pertain to transition status of the circuit breaker, previous status of the circuit breaker and present status of the circuit breaker. The ETU determines the transition status of the circuit breaker, indicating the shift from the OFF to the ON state. This determination is facilitated through a monostable multivibrator circuit triggered by a positive edge of a switch input, generating a signal to the ETU. The transition status is further calculated based on the quasi-stable state of transistors Q3 and Q4, with their collector voltages serving as indicators of OFF and ON states, respectively.
[0026] The system employs an energy-storing element (E1) to sustain the previous status of the circuit breaker, with charging and discharging times dictated by circuit parameters. The output of the previous status, when enabled with trip logging, evaluates the time elapsed since the last breaker fault opening. This information aids in decision-making processes to either withstand the fault or initiate an immediate trip within one cycle.
[0027] The present status of the circuit breaker is evaluated by monitoring the runtime position of the circuit breaker. This is achieved by detecting the state of transistor Q2 based on the status of a switch (SW1), which is shorted when the circuit breaker is closed and open when the breaker is opened. Additionally, the present status is determined by examining the collector voltage of transistor Q2, with low voltage indicating a closed breaker and high voltage indicating an open breaker.
[0028] In instances of open shot detection, where the breaker is closed and a short-circuit fault occurs, the ETU discerns a runtime fault through the transition status of the circuit breaker. This determination results in the ETU promptly tripping within the user-defined time delay, facilitated by an output signal indicating a low status. Furthermore, the system addresses scenarios involving closing followed by immediate opening (CO) detection. When the circuit breaker is closing onto a short-circuit fault within the delay in fault reoccurrence time, the ETU verifies the situation through the transition status of the circuit breaker being high and the previous status also being high. Subsequently, the ETU initiates an immediate trip within one cycle of the fault occurrence.
[0029] Moreover, the system accommodates situations where the circuit breaker is mechanically turned ON after a prior trip without carrying current. In this case, current is injected after the delay in fault reoccurrence time has elapsed. The ETU confirms the status based on the transition status of the circuit breaker being low, leading to the ETU tripping within the user-defined time delay. Besides, the system addresses scenarios involving the closing onto a short-circuit fault with an elapsed delay in fault reoccurrence time. The ETU conducts verification by assessing the transition status of the circuit breaker, which is high, and the previous status, which is low. Subsequently, the ETU initiates a trip within the user-defined time delay, ensuring a comprehensive response to diverse fault occurrences. The present disclosure can be described in enabling detail in the following examples, which may represent more than one embodiment of the present disclosure.
[0030] The advantages achieved by the system of the present disclosure can be clear from the embodiments provided herein. The system incorporates an electronic trip unit (ETU) meticulously configured to promptly sense and initiate the tripping of the circuit breaker within a single electrical cycle, specifically addressing instances where the circuit breaker closes onto a short-circuit fault immediately after reopening due to a runtime fault. This system ensures rapid detection and response to immediate short-circuit faults, minimizing downtime and averting potential damage to the electrical system. Additionally, the system incorporates mechanisms to prevent contact welding, a pivotal feature safeguarding the breaker's functionality and enhancing its longevity. This multifaceted system not only reduces the risk of damage to the breaker but also to connected equipment, thereby contributing to sustained long-term performance. The benefit lies in the system's capability to swiftly address faults, thereby significantly augmenting the overall reliability and efficiency of the electrical system. This approach to fault response and prevention the system's potential to facilitate uninterrupted operations, protect equipment, and prolong the lifespan of critical components within the electrical network. The description of terms and features related to the present disclosure shall be clear from the embodiments that are illustrated and described; however, the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents of the embodiments are possible within the scope of the present disclosure. Additionally, the invention can include other embodiments that are within the scope of the claims but are not described in detail with respect to the following description.
[0031] FIG. 1 illustrates an exemplary block diagram of the circuit breaker, in accordance with an embodiment of the present disclosure.
[0032] Referring to FIG. 1, a system of the circuit breaker can include essential components including the circuit breaker 102, electronic trip unit (ETU) 104 and breaker transition status 106-1, breaker previous status 106-2, and present breaker status 106-3. The system, further, includes a 24V DC power supply 108, breaker contacts 110, incomer phases (R-V-B-N) 112, auxiliary switch (AUX s/w) 114, external modules and releases 116, breaker open/close mechanism 118, flux shifting device (FSD) 120, remote command interface 122, Supervisory Control and Data Acquisition (SCADA) system 124, and current sensing unit 126.
[0033] The system can be equipped with the 24V DC power supply 108.. Breaker contacts 110 manage the electrical connections within the circuit, while incomer phases (R-V-B-N) 112 serve as the primary input points. The auxiliary switch (AUX s/w) 114 and external modules/releases 116 contribute to additional functionalities and control features. The breaker open/close mechanism 118 facilitates the operation of the circuit breaker.
[0034] The FSD 120 is incorporated to trip based on the trip command from ETU to operate breaker open/close mechanism 118. The system is designed with a remote command interface 122 for external control, allowing seamless integration with a SCADA system 124 for comprehensive monitoring and control. Additionally, the current sensing unit 126 provides real-time data on the electrical current flowing through the system, enhancing the system's ability to detect and respond to varying load conditions. Collectively, these components form a robust and versatile system for monitoring and controlling a circuit breaker in diverse operational environments. This configuration is designed to facilitate comprehensive monitoring, control, and transition management of the circuit breaker, ensuring efficient and reliable operation in diverse electrical environments.
[0035] Referring to FIG. 1, the circuit breaker 102 is a crucial component for safeguarding the power system from electrical faults. The electronic trip unit 104 serves as the "brain" of modern circuit breakers. The electronic trip unit 104 is capable of sensing and calculating various line parameters, including current, voltage, power, and frequency. The electronic trip units 104 provide a wide variety of protection against faults such as overload, short-circuit, overvoltage, undervoltage, over frequency, under frequency, over temperature, earth leakage and the like.
[0036] The electronic trip units 104 provide protections such as long-time overcurrent are used to protect cables, busbar, and busbar trunking systems against overload conditions. These are inverse time curve-based protections where, as the fault current increases trip time reduces. Short-time overcurrent protection helps to protect equipment against phase-to-phase, phase-to-neutral and phase-to-ground short circuits along with selectivity. Short-time overcurrent protections can be fixed delay-based or inverse time curve-based. Instantaneous protection helps to protect equipment against phase-to-phase, phase-to-neutral and phase-to-ground short circuits. It trips without additional time delay as soon as the setting current is exceeded.
[0037] Further, the user has the flexibility to set the threshold of various protections based upon load connected, coordination and selectivity to be achieved and the presence of harmonics in the system. Users can also set nominal current values using a hard/soft rating plug.
[0038] The electronic trip unit 104 continuously monitors the root mean square (RMS) current/voltage across the load, comparing it to the user-defined fault threshold. Upon the RMS current/voltage surpassing the user-set threshold, the trip unit decreases the delay count. Upon expiration of the delay, the trip unit issues a tripping command to the flux shifter coil, initiating breaker tripping for fault clearance. The electronic trip unit further provides a user interface enabling the visualization of metering parameters, modification of protection settings, and access to various breaker-related parameters. Some examples of breaker-related parameters can be breaker ON/OFF counters, % contact wear, internal/breaker terminal temperature etc.
[0039] Moreover, the electronic trip unit 104 offers configurable event logging for alarm, pickup, and trip conditions. Timestamped alarm and pickup events store fault sources, while trip logs comprehensively record fault current/voltage/frequency/power and tripping protection settings. These trip logs, timestamped for accuracy, are accessible through local human-machine interface (HMI) or remote access utilizing diverse communication techniques like Bluetooth, NFC, Modbus RS485, Modbus TCP/IP, Zigbee, Profibus, among others, as provided by the electronic trip unit.
[0040] Apart from basic protections, there are certain protections that are used to protect circuit breakers 102 and electronic trip units 104 from over-temperature or over-current conditions. These are internal protections and are not settable by the user. One such protection is making current release (MCR) in which the breaker closes onto the short-circuit fault. When the fault current is near/beyond the short circuit withstand capability of the breaker, magnetic repulsion of contacts takes place. Though this phenomenon helps in clearing higher-order faults, sometimes it may lead to welding of the breaker contacts due to frequent chattering before the complete opening of the breaker. This leads to both system and breaker damage. Thus, in such a condition it becomes important that the electronic trip unit senses the fault and issues a trip command within 1 cycle of fault occurring.
[0041] As per IEC 60947-2, electronic trip unit 104 needs to be powered up from the current carried by the breaker and the auxiliary supply is not mandatory. Hence, once the trip command is issued by ETU in case of fault, the power supply to ETU is cut off. Thus, in case of make-on faults, powerup time is also added to the total tripping time. Thus, the present disclosure provides MCR protection in a self-powered circuit breaker within 1 cycle of powerup. The electronic trip unit 104 is configured to consider the breaker status for three distinct scenarios, each associated with specific fault conditions and detection methodologies. These scenarios are detailed as follows:
[0042] In the event of a run-time fault in the system, the breaker is required to withstand the fault until the user-defined time delay elapses. This condition is known as "Open Shot" (O). The ETU 104 monitors the breaker status during this time delay, ensuring that the fault is sustained until the predefined duration expires.
[0043] Following the "Open Shot," if the breaker closes onto a short-circuit fault current within a specified time frame (referred to as Time_Delay_Fault_Reoccurrence), and the fault is near or beyond the short circuit withstand capability of the breaker, the ETU should promptly sense and trip the breaker. This situation is known as "Closing followed by Immediate Opening" (CO). The ETU continuously monitors the breaker status and fault current conditions. If the breaker closes within the defined time frame after the "Open Shot," and the fault condition is critical, the ETU triggers an immediate trip command.
[0044] In instances where the breaker is turned ON without current flowing through it and, after some time, current is introduced into the system, the breaker needs to carry the fault current until the withstand time or user-defined delay expires. The ETU must differentiate between runtime faults and closing-on faults. The ETU distinguishes between the absence of current during the breaker turning ON and other fault conditions by monitoring the breaker status and evaluating the nature and timing of the fault occurrence.
[0045] The present disclosure relates to a system for monitoring the circuit breaker that incorporates the ETU 104 designed to comprehensively assess the circuit breaker's status for MCR detection. The ETU determines the transition status of the circuit breaker, indicating the shift from the OFF to the ON state. This determination is facilitated through a monostable multivibrator circuit triggered by a positive edge of a switch input, generating a signal to the ETU. The transition status is further calculated based on the quasi-stable state of transistors Q3 and Q4, with their collector voltages serving as indicators of OFF and ON states, respectively.
[0046] The system employs an energy-storing element (E1) to sustain the previous status of the circuit breaker, with charging and discharging times dictated by circuit parameters. The output of the previous status, when enabled with trip logging, evaluates the time elapsed since the last breaker fault opening. This information aids in decision-making processes to either withstand the fault or initiate an immediate trip within one cycle.
[0047] The present status of the circuit breaker is evaluated by monitoring the runtime position of the circuit breaker. This is achieved by detecting the state of transistor Q2 based on the status of a switch (SW1), which is shorted when the circuit breaker is closed and opened when the breaker is opened. Additionally, the present status is determined by examining the collector voltage of transistor Q2, with low voltage indicating a closed breaker and high voltage indicating an open breaker.
[0048] In an embodiment, in an open shot detection, where the breaker is closed and a short-circuit fault occurs, the ETU discerns a runtime fault through the transition status of the circuit breaker. This determination results in the ETU promptly tripping within the user-defined time delay, facilitated by an output signal indicating a low status.
[0049] For example, the system pertains to open shot detection in the circuit breaker assembly. During normal operation, where the circuit breaker is in a closed state, providing electrical power to household appliances, an unforeseen short circuit may occur, giving rise to an "Open Shot" condition. The system expeditiously identifies the runtime fault through the monitoring of transition status, leading to a determination of a LOW output. Subsequently, the ETU, integral to the disclosed system, expedites the tripping process within a predefined time delay, effecting an isolation of the fault and safeguarding connected devices from potential damage.
[0050] In another embodiment, the system addresses scenarios involving closing followed by immediate opening (CO) detection. When the circuit breaker is closing onto a short-circuit fault within the delay in fault reoccurrence time, the ETU verifies the situation through the transition status of the circuit breaker being high and the previous status also being high. Subsequently, the ETU 104 initiates an immediate trip within one cycle of the fault occurrence.
[0051] For example, suppose the circuit breaker attempts to close onto a short circuit within a specific time frame after a previous fault occurrence (Time_Delay_Fault_Reoccurrence). The system, through the transition status and previous status verification, detects the "Closing followed by Immediate Opening (CO)" scenario. In response, the ETU initiates an immediate trip within 1 cycle of the fault occurrence, preventing a potentially hazardous situation.
[0052] In another embodiment, the system accommodates situations where the circuit breaker is mechanically turned ON after a prior trip without carrying current. In this case, the current is injected after the delay in fault reoccurrence time has elapsed. The ETU confirms the status based on the transition status of the circuit breaker being low, leading to the ETU tripping within the user-defined time delay.
[0053] For example, consider a case where the circuit breaker is previously tripped due to a fault, and after a certain delay, someone manually turns the breaker back ON. The system detects this situation, injects current after Time_Delay_Fault_Reoccurrence, and confirms the breaker is not initially carrying current (Breaker_Transition_Status is LOW). It then trips the ETU within the user-defined time delay, ensuring proper response to a potentially unsafe manual reactivation.
[0054] In yet another embodiment, the system addresses scenarios involving the closing of a short-circuit fault with an elapsed delay in fault reoccurrence time. The ETU conducts verification by assessing the transition status of the circuit breaker, which is high, and the previous status, which is low. Subsequently, the ETU initiates a trip within the user-defined time delay, ensuring a comprehensive response to diverse fault occurrences.
[0055] For example, suppose the breaker is closing onto a short-circuit fault, but the Time_Delay_Fault_Reoccurrence has elapsed since the previous fault. The system, by verifying the transition status and previous status, recognizes the scenario. It promptly trips the ETU within the user-defined time delay, preventing the breaker from closing onto a potentially persistent fault.
[0056] Thus, the present invention overcomes the drawbacks, shortcomings, and limitations associated with existing solutions, and provides a system incorporating an electronic trip unit (ETU) meticulously configured to promptly sense and initiate the tripping of the circuit breaker within a single electrical cycle, specifically addressing instances where the circuit breaker closes onto a short-circuit fault immediately after reopening due to a runtime fault. This system ensures rapid detection and response to immediate short-circuit faults, minimizing downtime and averting potential damage to the electrical system. Additionally, the system incorporates mechanisms to prevent contact welding, a pivotal feature safeguarding the breaker's functionality and enhancing its longevity. This multifaceted system not only reduces the risk of damage to the breaker but also to connected equipment, thereby contributing to sustained long-term performance. The benefit lies in the system's capability to swiftly address faults, thereby significantly augmenting the overall reliability and efficiency of the electrical system. This approach to fault response and prevention underscores the system's potential to facilitate uninterrupted operations, protect equipment, and prolong the lifespan of critical components within the electrical network.
[0057] FIG. 2A illustrates an exemplary circuit diagram for latching breaker position transition status, in accordance with an embodiment of the present disclosure.
[0058] In the disclosed system, the transition of the circuit breaker from the OFF to the ON state generates a HIGH pulse, referred to as Breaker_Position_Change_Status_Hold_Time. This signal, designated as Breaker_Transition_Status, is provided as an input to the ETU. FIG. 2A illustrates the Breaker status circuitry, employing a monostable multivibrator with Q3 in the stable state (ON) and Q4 in the OFF state during stability. The quasi-stable state occurs when Q3 is OFF, and Q4 is ON, triggered by a positive edge generated by the differentiator circuitry connected to the switch input. This positive edge is activated when the circuit breaker is closed, initiating a quasi-stable state for a duration determined by the time constant
[0059] Breaker_Transition_Status (106-1): In this case, a change in the breaker position from OFF to ON state generates a HIGH pulse for a fixed time frame (referred to as Breaker_Position_Change_Status_Hold_Time). This input to the ETU 104 is known as Breaker_Transition_Status, as shown in FIG. 2A. FIG. 2A illustrates the breaker status circuitry based on a monostable multivibrator, where the stable state is Q3 - ON and Q4 – OFF, and the Quasi-stable state is Q3 – OFF and Q4 – ON. The switch input is connected to differentiator circuitry which converts the level signal from the switch to an edge-triggered signal. The output of D3 is positive edge-triggered, and this signal becomes available once the circuit breaker is closed. A positive edge is generated at the output of D3, causing the circuit to undergo a Quasi-stable state for the time constant (referred to as Breaker_Position_Change_Status_Hold_Time), defined by R8 and C4.

[0060] The Collector voltage of Q3 in quasi-stable state is derived using below formula and is used by ETU as Breaker_Transition_Status.

[0061] FIG. 2B illustrates an exemplary circuit diagram for latching previous breaker status, in accordance with an embodiment of the present disclosure.
[0062] The disclosed circuit is illustrated in FIG. 2B, ensures the retention of the breaker status for a designated duration, even after the power supply to the electronic trip unit ETU 104 is discontinued. Incorporating an energy-storing element (E1), the circuit, whether powered by a battery or a capacitor, facilitates uninterrupted functioning when the ETU supply is cut off. Charging time and holding time of E1 depend on specific component values, and the holding time (referred to as Time_Delay_Fault_Reoccurrence) must exceed the Time_Delay_Fault_Reoccurrence for sustained power supply to the connected circuitry.
[0063] When the circuit breaker closes, SW1 is shorted, maintaining C1 at a low voltage. Upon breaker opening, SW1 opens, initiating the charging of C1 towards VCC through resistors R1, R3, and R6. The holding time of C1, governed by C1 and R5, is adjusted to match Time_Delay_Fault_Reoccurrence as per IEC standard 60947-1. Consequently, C1 preserves the breaker status if opened within Time_Delay_Fault_Reoccurrence from the reclosure instant.
[0064] This circuit's output is particularly valuable when trip logging is disabled. In the case of enabled trip logging, the elapsed time from the last breaker opening on a fault can be evaluated using the stored timestamp. Comparing this elapsed time with Time_Delay_Fault_Reoccurrence determines whether the breaker should endure the fault or trip within one cycle of the fault occurrence.
[0065] Breaker_Previous_Status (106-2): In this case, breaker status is latched for Time_Delay_Fault_Reocurrence even after the power supply turns OFF. FIG 2B. Shows the circuit diagram for storing the previous Breaker status. It can store the status even if the ETU supply is cut off. This circuit consists of energy storing element (E1) which gets charged when the ETU is powered ON. If this Energy storing element (E1) is a battery, then it may be capable of powering the circuit connected to it. If the E1 is a capacitor then the charging time of E1 may depend on value of R4 and E1 while the E1 holding time and discharging time will depend on the value of E1 ,R2 , R1 and effective input resistance offered by Q1. The holding time of E1(referred as Time_Delay_Fault_Reocurrence) have to be adjusted for greater than Time_Delay_Fault_Reocurrence so that it can give power to the rest of the circuitry for at least Time_Delay_Fault_Reocurrence.
[0066] When the circuit breaker is closed, SW1 may be shorted. So C1 input may be very few millivolt, and it may remain un-charged and once the circuit breaker is opened SW1 may be opened and C1 may starts charging towards VCC through R1, R3 and R6. The holding time of C1 depends on the value of C1 and R5, so the hold time of C1 has to be adjusted for Time_Delay_Fault_Reocurrence as per IEC standard 60947-1. With this C1 may hold status of Breaker if it may be opened within Time_Delay_Fault_Reocurrence from the reclosure instant.
[0067] The output of this circuit is specifically useful if the user has turned OFF the trip logging feature. In case the trip logging is enabled, the time lapsed from the last breaker opening on fault can be assessed by the timestamp stored along with the trip record. The time lapsed can be compared with Time_Delay_Fault_Reocurrence to ascertain if the breaker needs to withstand the fault or it needs to trip within 1 cycle of fault occurring
[0068] FIG. 2C illustrates an exemplary circuit diagram for reading the present breaker status, in accordance with an embodiment of the present disclosure.
[0069] The presented circuit captures the real-time status of a circuit breaker when the ETU 104 is activated using auxiliary power. It utilizes a configuration where, upon closure of the circuit breaker, a switch (SW1) shortens, causing a transistor (Q2) to turn ON with its collector voltage pulled Low. Conversely, when SW1 is opened, Q2 turns OFF, and its collector voltage is pulled High. The circuit's output is employed to monitor the current position of the circuit breaker.
[0070] Present_Breaker_Status (106-3): When the circuit breaker is closed, SW1 is shorted and Q2 is turned ON, and its collector voltage is pulled Low. While SW1 is opened Q2 is turned OFF and its collector voltage is Pulled High. Output of the mentioned circuitry is used to check the runtime position of the circuit breaker.
[0071] FIG. 3 illustrates an exemplary flow chart of a method for monitoring a circuit breaker, in accordance with an embodiment of the present disclosure.
[0072] The method 300 includes at block 302, ETU to evaluate status of the circuit breaker for detecting MCR. At block 304, determine the transition status of the circuit breaker, indicating a transition from the OFF to the ON state through a high pulse during the hold time for position change status.
[0073] At block 306, establish the previous status of the circuit breaker by storing the previous status for a delay in fault reoccurrence time. At block 308, evaluating the present status of the circuit breaker based on the runtime position, collectively distinguishing among the circuit breaker closing on fault, run-time fault, and faults occurring after the circuit breaker is been turned ON without current. At block 310, the ETU enable rapid fault detection response, by ensuring the ETU senses the fault and determines to either withstand the fault for a user-set delay time or initiate an immediate trip within one cycle of fault occurrence.
[0074] Regarding Table 1 Algorithm for detecting making current release is mentioned below:
Breaker_Transition_Status Breaker_Previous_Status or Time Lapsed from last Trip as per Trip Record Trip Time
HIGH ≥Time_Delay_Fault_Reocurrence Trip Delay set by user
HIGH