FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
1. Title of the invention: LOCAL BREAKER BACKUP PROTECTION SYSTEM TO
DETECT MALFUNCTIONING OF A BREAKER AND A METHOD THEREOF
2. Applicants):
(a) NAME : LARSEN & TOUBRO LIMITED
(b) NATIONALITY : An Indian Company
(c) ADDRESS : L & T House, Ballard Estate, Mumbai 400 001,
State of Maharashtra, India
3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed:

TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to a system and a method of failure monitoring for circuit breaker and more particularly, to a local breaker backup protection system to detect malfunctioning of a breaker and taking corrective action to isolate the fault and a method thereof.
BACKGROUND AND THE PRIOR ART
Failure monitoring of circuit breakers is used mainly to provide a double protection mechanism to the electrical system. Many a times due to various reasons the circuit breaker may not trip and may fatally damage the entire electrical system. Under such circumstances it is quite necessary to provide a protection mechanism that detect the failure of circuit breaker and provide a corrective measure to isolate the fault.
Some of the prior art documents in the same field of invention are listed below: WO2011157306 provides a breaker failure protection system for a high voltage direct current, HVDC, circuit breaker is provided. The circuit breaker is arranged for interrupting a DC circuit upon reception of a trip signal. The protection system comprises a current sensor, at least one inductor and a breaker failure detection unit. The current sensor is arranged for measuring a current I(t) through the DC circuit. The at least one inductor is connected in series with the DC circuit. The breaker failure detection unit is arranged for assessing, whether the circuit breaker has failed, and sending, if the circuit breaker has failed, a trip signal to an adjacent circuit breaker. The assessment is based on the measured current. The stability of HVDC grids may be improved by sending, in case of a breaker failure, a trip signal to adjacent circuit breakers. Further, a method of breaker failure protection for an HVDC circuit breaker is provided.

CN201852919 provides a utility model of a failure monitoring device for a circuit breaker. The failure monitoring device comprises a data processing module, a data wireless transmitting and receiving module and a display screen, wherein a communication interface of the data processing module is connected with a communication interface of the data wireless transmitting and receiving module; the power supply input end of the data processing module, the power supply input ends of the data wireless transmitting and receiving module and the power supply inlet end of the display screen are respectively connected with the output end of a power supply control module; and the input end of the power supply control module is connected with a battery.
Although the available prior art system provide required protection, the said prior arts are costly and provides a complex mechanism. The present invention therefore provides a system for failure monitoring having the advantages of convenience in use, low installation cost and a simple and reliable design.
Present invention provides a local breaker backup protection system to detect malfunctioning of a breaker and taking corrective action to isolate the fault and a method thereof.
OBJECTS OF THE INVENTION
A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.
Another object of the present invention is to provide a local breaker backup protection system to detect malfunctioning of a breaker and taking corrective action to isolate the fault.

Yet another object of the present invention is to provide a method for backup protection to detect malfunctioning of a breaker and taking corrective action to isolate the fault.
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.
There is provided system and method of failure monitoring for circuit breaker.
According to one embodiment of the present invention, there is provided a local breaker backup protection system to detect malfunctioning of a downstream breaker and taking corrective action to isolate the fault in LV/MV switchboards by tripping a upstream breaker, said protection system comprising a numerical relay for detecting and providing tripping signal to the upstream breaker; a DI unit for detecting the breaker status using inputs from breaker auxiliary contacts; a breaker failure alarm means providing failure notification for said downstream breaker.
Other embodiment of the present invention provides method of local breaker backup protection to detect malfunctioning of a downstream breaker and taking corrective

action to isolate the fault in LV/MV switchboards by tripping a upstream breaker, said method comprising the steps of detecting and providing tripping signal to the upstream breaker using a numerical relay;_providing the breaker status using inputs from breaker auxiliary contacts using a HMI unit; and providing failure notification for said downstream breaker using a breaker failure alarm means.
Yet other embodiment of the present invention provides a numerical relay comprising a CPU controller having a protection algorithm logic installed therein, an analog/digital converter for capturing current analog samples from a current transformer secondary and converting said analog signals into digitized form; a data acquisition and metering section taking said digitized inputs from said analog/digital converter and advancing said digitized signal to said CPU controllers.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
In the appended drawings:
Fig 1 illustrates the breaker backup protection system to detect malfunctioning of a
breaker.
Fig. 2 illustrates the protection algorithmic logic installed in CPU controllers.
DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description. .

Reference is first invited to Fig 1 where the local breaker backup protection system to detect malfunctioning of a breaker and taking corrective action to isolate the fault is shown. It shows different units like Data acquisition and metering section, CPU controller, Numerical relay etc.
Fig. 2 shows the protection algorithm logic installed in the CPU controller in a coded form which is embedded inside the relay.
The invented system is thus a local breaker backup protection system to detect malfunctioning of a breaker and taking corrective action to isolate the fault.
DETAILED DESCRIPTION OF THE INVENTION
Accordingly in the present invention there is provided a local breaker backup protection system to detect malfunctioning of a breaker and taking corrective action to isolate the fault. It provides a Local breaker backup protection (LBB).
This invention is related to detection of malfunctioning of breaker and raising a subsequent alarm as preventive measure. If a breaker does not trip even if a trip command is issued by the protection algorithm logic due to a fault, it is extremely critical .This logic will be used in a numerical relay as a part of LV/MV switchboards. The algorithm will go as flow logic into the firmware build or embedded systems of the relay. The algorithm will be coded inside the relay firmware.
This invention elucidates the application space and concept of Breaker Failure and illustrates the HMI settings and the firmware logic to be incorporated to include this feature in New Feeder Protection relay. In a power system, protection relay plays an

important role for proper and uninterrupted functioning of the healthy section of the system. The main objective of the protection relay is detection and tripping/blocking of the breaker, depending upon the application, in order to isolate the faulty section of the system from the healthy part.
Figure 1 depicts the flow of the inputs /commands to the corresponding hardware of the numerical relay. There are numerous components in terms of embedded systems (hardware) in the numerical relay of which Data acquisition & metering and CPU controller are the two main sub sections of the relay. Initially the current transformer secondary inputs i.e. phase currents which are analog inputs are fed to the Analog/Digital (A/D) converter located inside the relay. The A/D converter captures the current analog samples per cycle and converts into digitized form. 64 samples / cycle are captured by the A/D converter. These digitized samples from A/D converter go into the Data acquisition and metering section of the numerical relay and further to the protection algorithm logic.
The protection algorithm logic is installed in the CPU controller, in a coded form, which is embedded inside the relay. Through Data acquisition and metering section, the current inputs advance to CPU controller where the protection algorithm logic is processed. Here in this case after the procession of the logic, the digital output of the relay (hardware) gets the signal to trip the upstream breaker and the trip command is sent to the Digital Input of that breaker through hardware interface and an alarm is also raised.
During fault conditions of a power system, the breaker needs to be tripped to isolate the faulty part of the power system network. Though infrequent, but the circuit breaker may fail to trip. The possible methods of detection are as follows:-Breaker auxiliary contacts detecting breaker status (Breaker is closed) even after a timer

(timer value= breaker tripping time + a buffer) and fault current is still flowing interpreting that the breaker has not tripped resulting to failure of clearing the fault.
Action for this is LBB protection (Local breaker backup protection). If the downstream breaker fails to clear the fault, a DO is fed from the downstream breaker as DI of the upstream breaker to trip it. Breaker failure alarm provision is there which is user configurable.
Settings:-
The following settings are required on the HMI:-
Breaker Failure feature (Enabled/Disabled)
Breaker tripping time (10 ras to 10 sees in steps of 10 ms, default value= 50 ms)
Inputs
Status of the Breaker failure feature (enabled/disabled)
Three Phase currents (la, lb, Ic)
Breaker failure initiate element (In Flex logic to be configured normally phase O/C
elements are considered)
Outputs
The Flex logic operand bit for Breaker Failure goes high. If the alarm is configured, the CPU register containing the alarm value also goes high.
Abbreviations used:
HMI: Human machine interface CPU: Central processing unit O/C: Overcurrent A/D: Analog to digital LBB: Local breaker backup

DO: Digital output
DI: Digital input
BF: Breaker failure
Inom: Nominal current
BKR: Breaker
BFI: Breaker Failure Initiate
Although the embodiments herein are? described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein scope of the claims.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

WE CLAIM:
1. A breaker backup protection system to detect malfunctioning of a downstream breaker and taking corrective action to isolate the fault in LV/MV switchboards by tripping an upstream breaker, said protection system comprising:
a relay means for detecting and providing tripping signal to the upstream breaker;
a DI unit for detecting the breaker status (Close/Open) using inputs from breaker auxiliary contacts;
a breaker failure alarm means providing failure notification for said downstream breaker;
wherein said relay means including a CPU controller means having a protection algorithm logic installed therein,
an analog/digital converter for capturing current analog samples from a current transformer secondary and converting said analog signals into digitized form;
a data acquisition and metering section taking said digitized inputs from said analog/digital converter and advancing said digitized signal to said CPU controllers
wherein the controller logic checks the Breaker failure initiated by means of detecting any preselected Electrical fault arising in system through current and voltage value from Data Acquisition & metering and protection settings, and breaker status as (Close/Open) through digital input from breaker contacts and the breaker back up is enabled through controller (ON/OFF); said controller generating a signal to prohibit other related breaker to act in LBB and starts a

TIMER with specified time delay and when failure of breaker to trip is detected from DI status of breaker after Timer expires and state of BFI is still (On/Off); said controller generating breaker failure alarm and gives an indication to upstream breaker to trip on same BFI occurred in downstream.
2. System as claimed in claim 1 wherein said relay means is a numerical relay
3. System as claimed in claim 1 wherein said CPU controller means comprising processing the protection algorithm logic and providing trip signal to said upstream breaker.
4. System as claimed in claim 1 wherein said CPU controller means being configured with said breaker failure alarm means to provide tripping signal to said upstream breaker on receiving failure notification from said breaker failure alarm means.
5. A method of protection of breakers to detect malfunctioning of a downstream
breaker and taking corrective action to isolate the fault in LV/MV
switchboards by tripping a upstream breaker, said method comprising the
steps of:
detecting and providing tripping signal to the upstream breaker using a relay means; - detecting the breaker status using inputs from breaker auxiliary contacts using a DI unit; and
providing failure notification for said downstream breaker using a breaker failure alarm means.
6. Method as claimed in claim 5 further comprising the steps of
capturing current analog samples per cycle and converting into digitized form using an analog/digital converter;

said digitized samples from said analog/digital converter fed to a data acquisition and metering section;
output from said data acquisition and metering section further fed to a CPU controller where the protection algorithm logic is processed;
said CPU controller further generating the flex logic operand to block the over-current elements.
7. Method as claimed in claim 6 wherein said the protection algorithm logic is processed by said CPU controller and provide trip signal to said upstream breaker.
8. Method as claimed in claim 6 wherein said CPU controller is configured with said breaker failure alarm means to provide tripping signal to said upstream breaker on receiving failure notification from said breaker failure alarm means.

9. A breaker backup protection system to detect malfunctioning of a downstream breaker and taking corrective action to isolate the fault in LV/MV switchboards by tripping a upstream breaker as herein substantially described and illustrated with reference to the accompanying drawings.
10. A method of breaker backup protection to detect malfunctioning of a downstream breaker and taking corrective action to isolate the fault in LV/MV switchboards by tripping a upstream breaker as herein substantially described and illustrated with reference to the accompanying drawings.