DESC:TECHNICAL FIELD

The present invention relates generally to a circuit breaker and various modules connected to it and, particularly, to the modules that communicate with the electronic trip unit (ETU) and certain modules that have access to the ETU settings.

BACKGROUND

An electronic trip unit provides the user to view and change the various ETU settings. With advancements in the technology, ETU can communicate with various other terminals i.e., supplementary modules such as M3U, Test-kit, Panel Display, Programmable Relay Module, among others, to provide high-end and improved functionalities. In such a scenario, limited access is required so that settings can be changed by the appropriate modules only. The present invention ensures the above. Any unwanted access of the settings could lead to corruption of the data. This could further result in hazardous consequences like nuisance tripping, flash-over or damage to the electric installation.

The prior-art document US 20110093639 A1 discloses a secure communications between and verification of authorized can devices wherein Encrypted encoding and decoding of identification data of CAN bus devices for communications there between provides deterrence of theft and unauthorized access of these secure CAN bus devices. Each one of the CAN bus devices is considered a “node” on the CAN bus for communications purposes. By using a unique encryption code stored in each of the “authorized” CAN bus devices, unauthorized CAN bus nodes will not be able to communicate with the authorized, e.g., secure, CAN bus nodes functioning in a CAN system. However, the patent document 20110093639 A1 uses a security peripheral such as the KEELOQ® system, a registered trademark of Microchip Technology Incorporated, used to encrypt/decrypt data for transmission via the CAN bus to authorized CAN bus nodes. KeeLoq is a proprietary hardware-dedicated block cipher. KeeLoq "code hopping" encoders encrypt a 0-filled 32-bit block with KeeLoq cipher to produce a 32-bit "hopping code". For simplicity, individual "code hopping" implementations do not use cryptographic nonces and clock drift excludes the possibility of using time stamping. This makes the protocol inherently vulnerable to replay attacks For example, by jamming the channel while intercepting the code, a thief can obtain a code that may still be usable at a later stage.

In the view of above mentioned drawbacks there exists a need to provide a technical solution that enables limited access to modules in the system and enhances system security.

SUMMARY

This summary is provided to introduce concepts related to a method for accessing electronic trip unit settings in circuit breakers. This summary is not intended to identify essential features of the subject matter nor is it intended for use in determining or limiting the scope of the subject matter.

In one implementation, a method for accessing electronic trip unit settings in circuit breakers is disclosed.

In one implementation, the present invention relates to circuit breakers and various modules connected to it. These modules communicate with the ETU and certain modules have access to the ETU settings. But only few modules are authorized to change the settings providing limited access to settings.

In one implementation, the 'identifier' of a customized message based CAN protocol to provide limited access are used. Hence, the identifier’s are used to provide then limited access in a way that is by no means obvious and requires extensive firmware.

Accordingly, in one implementation, a system (100) for providing a communication between an electronic trip unit (ETU) (102) of a circuit breaker (100) and at least one module (104) of said circuit breaker (100) thereby providing a limited access to various protection and system settings stored in a memory of said electronic trip unit (ETU) (102) is disclosed. The system (100) comprises of a communication protocol (106) to provide said communication between said electronic trip unit (ETU) (102) of said circuit breaker (100) and said at least one module (104) of said circuit breaker (100). The system is characterized in that said at least one module (104) of said circuit breaker (100) communicates with said electronic trip unit (ETU) (102) of said circuit breaker (100) over at least one message with a specific CAN frame structure (300) based CAN protocol (106), wherein said at least one message has a message identifier unique for said at least one module and defines data to be communicated and a priority of said at least one message.

In one implementation, a method (400) for providing a communication between an electronic trip unit (ETU) (102) of a circuit breaker (100) and at least one module (104) of said circuit breaker (100) thereby providing a limited access to various protection and system settings stored in a memory of said electronic trip unit (ETU) (102) is disclosed. The method (400) comprises of:
· providing (402) a communication protocol to enable said communication between said electronic trip unit (ETU) of said circuit breaker and said at least one module of said circuit breaker, characterized in that
· communicating (404) said at least one module of said circuit breaker with said electronic trip unit (ETU) of said circuit breaker over at least one message with a specific CAN frame structure based CAN protocol, wherein
· said at least one message has a message identifier unique for said at least one module and defines data to be communicated and a priority of said at least one message.

In one implementation, the present invention is technically advanced and is unique from the other existing techniques, in the way, the CAN query or Universal identifiers are created. Further, as per the present invention, system does not need to remember the data pointers of the memory location at which the data is stored. The modbus memory address itself indicates the data pointers in the Universal Identifier (UID). Also the CAN IDs are designed in such a way that the query details like the type of module, the data accessed, the message type etc is clear from the ID itself.

In one implementation, The CAN identifier provides the details like the Module ID, Data Header, Message Type, Data ID which is a Universal ID (UID).The UID is the adaptation of the Modbus query. It indicates the Index pointer of the data stored in the RAM. This avoids the complexity of having serial CAN IDs which may be difficult to interpret.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

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

Figure 1 illustrates a network implementation of an ETU system for accessing electronic trip unit settings in circuit breakers is shown, in accordance with an embodiment of the present subject matter.

Figure 2 illustrates a method of authentication for accessing electronic trip unit settings in circuit breakers is shown, in accordance with an embodiment of the present subject matter.

Figure 3 illustrates a message frame format is shown, in accordance with an embodiment of the present subject matter.

Figure 4 illustrates a method (400) for providing a communication between an electronic trip unit (ETU) (102) of a circuit breaker (100) and at least one module (104) of said circuit breaker (100) thereby providing a limited access to various protection and system settings stored in a memory of said electronic trip unit (ETU) (102) is shown, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

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

The terms and words used in the following description are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention.

It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

In one implementation, a method for accessing electronic trip unit settings in circuit breakers.

In one implementation, the overall system is shown in figure 1, which includes an electronic trip unit, relay module, communication module, etc. These modules can view various protection and system settings that are stored in data flash of ETU.

In one implementation, a system (100) for providing a communication between an electronic trip unit (ETU) (102) of a circuit breaker (100) and at least one module (104) of said circuit breaker (100) thereby providing a limited access to various protection and system settings stored in a memory of said electronic trip unit (ETU) (102) is disclosed. The system (100) comprises of a communication protocol (106) to provide said communication between said electronic trip unit (ETU) (102) of said circuit breaker (100) and said at least one module (104) of said circuit breaker (100). The system is characterized in that said at least one module (104) of said circuit breaker (100) communicates with said electronic trip unit (ETU) (102) of said circuit breaker (100) over at least one message with a specific CAN frame structure (300) based CAN protocol (106), wherein said at least one message has a message identifier unique for said at least one module and defines date to be communicated and a priority of said at least one message.

In one implementation, said at least one module (104) is selected from a group of modules (104-n) comprising a COM module (104-1), a relay module (104-2), a display module, and a combination thereof.

In one implementation, an identifier list comprising said message identifier unique for said at least one module is maintained and stored in a memory of said ETU (102).

In one implementation, the system is characterized in that it provides a first level of authentication and a second level authentication.

In one implementation, said first level of authentication is provided by using a user identification and password, wherein at least one user enters a password, and said system compares said entered password with previously stored password in said memory of said ETU (102), and based on a matching said first level of authentication is provided.

In one implementation, said second level of authentication is provided through a message identifier unique for said at least one module and said ETU (102) is preconfigured to accept setting commands from authorized said at least one module (104).

In one implementation, said identifier list is configured in every module so that said module (104) determines which data on a data lines is meant for which module, wherein if said identifier of said message on the data lines matches the one pre-configured in said module (104), only then said access is provided.

As a first level of authentication, the module that needs to access the settings data is required to enter a password as shown in figure 2. Whenever the user wants to view/change the settings, he initiates the same through a display module. The user is prompted on the display to enter the password. Once after entering the password and pressing the key enter, the controller stores the password entered by the user in a buffer and compares it with previously stored password. If both match, the user is allowed to change the settings. In the Event that the Password does not match, a message is displayed stating ‘User Authentication Failed’. In such a scenario, the user is not allowed to access the settings and previously stored settings stay applied. The password for the setting is customizable and can be altered by authorized personnel if required. To avoid complexity in the system, the password is maintained common across all modules.

In one implementation, all the modules communicate with ETU over a message based CAN protocol. CAN is based on the “broadcast communication mechanism”, which is based on a message-oriented transmission protocol. It defines message contents rather than stations and station addresses. Every message has a message identifier, which is unique within the whole network since it defines content and also the priority of the message. This is important when several stations compete for bus access (bus arbitration).

As a result of the content-oriented addressing scheme a high degree of system and configuration flexibility is achieved. It is easy to add stations to an existing CAN network without making any hardware or software modifications to the present stations as long as the new stations are purely receivers. This allows for a modular concept and also permits the reception of multiple data and the synchronization of distributed processes. Also, data transmission is not based on the availability of specific types of stations, which allows simple servicing and upgrading of the network. In our application we have customized the application layer of the CAN protocol to meet our requirements.

Changing the settings of the ETU is possible, but only authorized modules should change the settings over the CAN protocol. When any module wants to change or access the data, it sends the necessary request through the following CAN frame structure. Every message that needs to be sent has an identifier, and the identifier list required or meant for a module is pre-stored in the ETU memory. This ensures that the access to the memory of the Electronic Trip Unit i.e. the settings, is by the authorized modules only.

Additionally, the identifier list is configured in every module so that the module can ascertain which data on the data lines is meant for which module. If the identifier of the message on the data lines matches the one pre-configured in the module, only then can it access it.

This ensures limited access to modules and enhances system security.

In one implementation, each module that communicates with the trip unit will send the message following the identifier. The trip unit may verify using an algorithm if the particular message / data request / access request should be granted to the module. The algorithm that may be used to verify the particular message / data request / access request should be granted to the module is as given below:
1. The human machine interface (HMI) or programmable logic controller (PLC) software requests for a particular data using a register address as per the Memory Map.
2. The Modbus query is converted to a CAN query to get the data from ETU or any particular module. It may be understood by the person skilled in that art the conversion of Mod bus query to a CAN query is not a new technique, however, the way the CAN query or Universal identifiers are created is advancement in the existing techniques.
3. The CAN response from the recipient is again converted to Modbus protocol format which is understood by the HMI.

The present invention is technically advance and unique from the other existing techniques is in the way the CAN query or Universal identifiers are created. Further, as per the present invention, the algorithm does not need to remember the data pointers of the memory location at which the data is stored. The modbus memory address itself indicates the data pointers in the Universal Identifier (UID). Also the CAN IDs are designed in such a way that the query details like the type of module, the data accessed, the message type etc is clear from the ID itself.

This ensures that the access to the memory of the Electronic Trip Unit i.e. the settings, is by the authorized modules only. Additionally, the identifier list is configured in every module so that the module can ascertain which data on the data lines is meant for which module. If the identifier of the message on the data lines matches the one pre-configured in the module, only then can it access it. This ensures limited access to modules and enhances system security. Additionally the module IDs are incorporated in the identifier itself. The invention also ensures that two modules of the same type (say 2 panel displays) will be denied access.

Referring now to figure 3 illustrates a message frame format is shown, in accordance with an embodiment of the present subject matter.

In one implementation, CAN identifier is a 29 bit Extended format. The present invention is technically advanced from the other existing identifier and their generation techniques in the way that the identifier is configured. The CAN identifier provides the details like the Module ID, Data Header, Message Type, Data ID which is a Universal ID (UID).The UID is the adaptation of the Modbus query. It indicates the Index pointer of the data stored in the RAM. This avoids the complexity of having serial CAN IDs which may be difficult to interpret.

Referring now to figure 4, a method (400) for providing a communication between an electronic trip unit (ETU) (102) of a circuit breaker (100) and at least one module (104) of said circuit breaker (100) thereby providing a limited access to various protection and system settings stored in a memory of said electronic trip unit (ETU) (102) is shown, in accordance with an embodiment of the present subject matter.

In one implementation, a method (400) for providing a communication between an electronic trip unit (ETU) (102) of a circuit breaker (100) and at least one module (104) of said circuit breaker (100) thereby providing a limited access to various protection and system settings stored in a memory of said electronic trip unit (ETU) (102) is disclosed.

At step 402, a communication protocol to enable said communication between said electronic trip unit (ETU) of said circuit breaker and said at least one module of said circuit breaker is provided.

At step 404, said at least one module of said circuit breaker communicates with said electronic trip unit (ETU) of said circuit breaker over at least one message with a specific CAN frame structure based CAN protocol, wherein said at least one message has a message identifier unique for said at least one module and defines date to be communicated and a priority of said at least one message.

At step 406 an identifier list comprising said message identifier unique for said at least one module is maintained and stored in a memory of said ETU.

At step 408, a first level of authentication and a second level authentication is provided.

At step 410, said identifier list in every module so that said module determines which data on a data lines is meant for which module is configured, wherein if said identifier of said message on the data lines matches the one pre-configured in the module, only then said access is provided.

It will be understood by the person skilled in the art that, the details of steps performed by the system are provided in the above description, the unnecessary repetition of the data is avoided to avoided complexity.

In one implementation, it will be understood by the person skilled in the art that the above mentioned method may be performed by said microcontroller and the set of instruction or module may be stored in the available memory of the micro controller or the circuit breaker. Further, said firmware may be available for performing the above motioned steps when coupled with the micro controller.

In one implementation, the identifiers are used to provide limited access in a way that is by no means obvious and requires extensive firmware.

Although a method for accessing electronic trip unit settings in circuit breakers is been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations a can interface between an electrical trip unit of a circuit breaker is disclosed.
,CLAIMS:1. A system (100) for providing a communication between an electronic trip unit (ETU) (102) of a circuit breaker (100) and at least one module (104) of said circuit breaker (100) thereby providing a limited access to various protection and system settings stored in a memory of said electronic trip unit (ETU) (102), said system (100) comprising:
a communication protocol (106) to provide said communication between said electronic trip unit (ETU) (102) of said circuit breaker (100) and said at least one module (104) of said circuit breaker (100), CHARACTERIZED IN THAT said at least one module (104) of said circuit breaker (100) communicates with said electronic trip unit (ETU) (102) of said circuit breaker (100) over at least one message with a specific CAN frame structure (300) based CAN protocol (106), wherein
said message has a message identifier unique for said at least one module and defines data to be communicated and a priority of said at least one message.

2. The system (100) as claimed in claim 1, wherein said at least one module (104) is selected from a group of modules (104-n) comprising a COM module (104-1), a relay module (104-2), a display module, and a combination thereof.

3. The system (100) as claimed in claims 1 to 3, wherein an identifier list comprising said message identifier unique for said at least one module is maintained and stored in a memory of said ETU (102), and said message identifier comprises at least detail selected from a group comprising a Module ID, a Data Header, a Message Type, a Data ID which is a Universal ID (UID), or any combination thereof.

4. The system (100) as claimed in claims 1 to 4 is characterized in that it provides a first level of authentication and a second level authentication.

5. The system (100) as claimed in claims 1 to 5, wherein said first level of authentication is provided by using a user identification and password, wherein at least one user enters a password, and said system compares said entered password with previously stored password in said memory of said ETU (102), and based on a matching said first level of authentication is provided.

6. The system (100) as claimed in claims 1 to 6, wherein said second level of authentication is provided through a message identifier unique for said at least one module and said ETU (102) is preconfigured to accept setting commands from authorized said at least one module (104).

7. The system as claimed in claims 1 to 7, wherein said identifier list is configured in every module so that said module (104) determines which data on a data lines is meant for which module, wherein if said identifier of said message on the data lines matches the one pre-configured in said module (104), only then said access is provided.

8. A method (400) for providing a communication between an electronic trip unit (ETU) (102) of a circuit breaker (100) and at least one module (104) of said circuit breaker (100) thereby providing a limited access to various protection and system settings stored in a memory of said electronic trip unit (ETU) (102), said method (400) comprising:
providing (402) a communication protocol to enable said communication between said electronic trip unit (ETU) of said circuit breaker and said at least one module of said circuit breaker, characterized in that
communicating (404) said at least one module of said circuit breaker with said electronic trip unit (ETU) of said circuit breaker over at least one message with a specific CAN frame structure based CAN protocol, wherein
said at least one message has a message identifier unique for said at least one module and defines date to be communicated and a priority of said at least one message.

9. The method as claimed in claim 8 comprises maintaining and storing (406) an identifier list comprising said message identifier unique for said at least one module in a memory of said ETU.

10. The method as claimed in claims 8 and 9 is characterized in providing (408) a first level of authentication and a second level authentication.

11. The method as claimed in claims 8 and 9 comprises configuring (410) said identifier list in every module so that said module determines which data on a data lines is meant for which module, wherein if said identifier of said message on the data lines matches the one pre-configured in the module, only then said access is provided.