FORM 2
THE PATENTS ACT, 1970 COMPLETE SPECIFICATION
(See Section 10)
A COMMUNICATION SYSTEM FOR ELECTRICAL INTERRUPTION DEVICES
numbered as dated
INVENTORS:
1. JIGAR KUMAR LAKSHMANBHAI PATEL
2. SONAL KHINVASARA
3. RATNADEEP N. PINGALE
APPLICANT:
LARSEN & TOUBRO LIMITED
L&T House, Ballard Estate, P.O. Box No 278,
Mumbai, 400 001, Maharashtra,
INDIA


A COMMUNICATION SYSTEM FOR ELECTRICAL INTERRUPTION DEVICES
A) TECHNICAL FIELD
The present invention relates to electrical interruption devices and more particularly to the communication and control system through which the electrical interruption devices interacts with various modules coupled thereof.
B) BACKGROUND OF THE INVENTION
In a factory-power distribution system, power is generated by a power generation company and supplied to a factory and thereafter distributed around the factory to various equipment such as, for example, motors, welding machinery, computers, heaters, lighting, and the like. Power distribution systems of this type are typically centrally located in switch gear rooms or substations. From there, power is divided up into branches such that each branch supplies power to a portion of the factory and/or specified loads. Frequently, transformers are disposed throughout the factory to step down the supply voltage to that required by specific pieces of equipment or portions of the factory.


It is quite common to provide protective devices such as circuit breakers or fuses in at least each branch so that not only may each piece of equipment be protected but any problems associated with one piece of equipment does not ripple to adjacent or interconnected pieces of equipment. Further, when circuit breakers are utilized, they are used to detect more than just large overcurrent conditions caused by short circuit faults. In addition, they frequently detect lower level long-time overcurrent conditions and excessive ground currents.
Electronic circuit breakers which are installed in industrial environment and having high EMI/EMC effect are adjustable so as to fit a particular load or condition by the end user without designing or specifying different breakers. Breakers of this type typically include a microcontroller coupled to one or more current sensors. The microcontroller continuously monitors the digitized current values using a curve which defines permissible time frames in which both low-level and high-level overcurrent conditions may exist. If an overcurrent condition has maintained for longer than its permissible time frame, the breaker is tripped.
Because of the flexibility and configurability of microprocessor controlled circuit breakers and the large size and complexity of the industrial settings in which they are used, there is a provision of a centralized system providing communications having defined protocols to and from the circuit breakers. The communication system also provides reconfigurability of the circuit breakers from a centralized location and monitors


the circuit breakers at a centralized location. Also with the electronic circuit breakers there are configured various modules via the communication system which continuously interacts thereof. Normally, modules have large information that cannot be transmitted to electronic circuit breakers in a single communication. Large information need to be divided into smaller packet size data, so it can fit into communication media protocol. Every data exchange between module and electronic circuit breakers should be reliable. If any frame is missing / gets corrupt, device should response with request to retransmit missing data. Robust flow control is required for reliable data transmission.
Module networks should not be affected by temporary error in one module. Traditional network protocols used in electronic circuit breakers are not able to distinguish between short disturbances from permanent failures. Traditional serial protocol also does not support error recovery, automatic CRC Computation or message retransmission. Implementation of CRC Computation and message retransmission in traditional serial protocols bring additional burden on microcontroller. Electronic circuit breakers receive various data from different devices. Data from some devices have higher priority than other. With traditional serial protocol data priority can be implemented in software, but this is liable to add additional burden on CPU. Traditional serial protocol also does not support reliable, robust and fault tolerant communication at higher data rates.


Such a condition is however unacceptable and accordingly needs an improvement. Accordingly, it is an object of the present invention to provide such a communication system that eliminates at least one of the above mentioned drawbacks.
C) SUMMARY OF THE INVENTION
According to an aspect of the present invention, a communication system for an electrical interruption means comprises of an electronic tripping device configured to an application specific preprogrammed module. A controller area network is further inclusive of a defined communication protocol and a communication bus. The controller area network enables the electronic tripping device to communicate with the application specific preprogrammed module via the communication bus. Also, a microcontroller for monitoring and controlling data flow between the electronic tripping device and the module is configured to the same.
Alternatively, a plurality of modules may also be configured to the electronic tripping device via the same controller area network having a defined communication protocol.
Preferably, in the communication protocol of the controller area network, data flow is prioritized between the plurality of modules configured to the electronic tripping device wherein the prioritization of data between the modules depends on a unique module ID assigned to each of the module.


Preferably, the data flow between the electronic tripping device and the module is processed in small packets via the communication bus.
Preferably, in the communication protocol of the controller area network corrupt data is automatically retransmitted between the module and the electronic tripping device. Preferably, the preprogrammed module may comprise of an application layer and a transport layer. Also the electronic tripping device has a preinstalled application layer and transport layer wherein same transport layer is configured to the plurality of modules. According to another aspect of the present invention a system for automatic detection of a module with an electrical interruption means comprises of an electronic tripping device for sending messages to a non-configured application specific preprogrammed module coupled to the electronic tripping device and a controller area network including a defined communication protocol and a communication bus. The controller area network enables the electronic tripping device to communicate with the non-configured application specific module via the communication bus, wherein the electronic tripping device interrogates the module by sending broadcast message followed by configuration data and ping request to which reciprocal of the module.
Other objects, features and advantages of the invention will be apparent from the drawings, and from the detailed description that follows below.


D) BRIEF DESCRIPTION OF THE DRAWINGS
Reference will be made to embodiments of the invention, examples of which may be illustrated in the accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in the context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
FIGURE.l illustrates the interface between the application layer and the transport layer according to an embodiment of the present invention.
FIGURE.2 illustrates the software architecture of the electronic device and the modules according to an embodiment of the present invention.
FIGURE.3 illustrates the flow control mechanism between the electronic tripping device and the modules of Fig 2.
FIGURE.4 shows the network join flow chart of automatic module detection method according to an embodiment of the present invention according to an embodiment of the present invention.


E) DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to the field of electrical interruption devices and more particularly to the communication and control system via which the electrical interruption devices interacts with various modules coupled thereof. The present invention would be better understood in conjunction with a following description of various embodiments and the figures that details the working principle of the present invention.
In the following description, references to the drawings, certain terms are used for conciseness, clarity and comprehension. It is assumed by one skilled in the art that there are to be no unnecessary limitations implied from such references, besides the limitations imposed by the prior art, because such terms and references are used for descriptive purposes only and intended to be broadly construed. Furthermore, the description and the drawings are for illustrative purposes only and not to be construed as limited to the exact details shown, depicted, represented, or described. Further, Reference in the specification to the phrases like "one embodiment", or "another embodiment" etc. means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the above-mentioned phrase in various places in the specification are not necessarily all referring to the same embodiment.


The Controller Area Network (CAN) (not shown) is a serial communication protocol which efficiently supports distributed real-time control. It has features like Prioritization of messages, guarantee of latency time, multicast reception with time synchronization, error detection, automatic retransmission of corrupted message, distinction between temporary errors and permanent failures etc. Further, it is also to be noted that In the present invention CAN is use as communication backbone to connect various modules like Digital Input/Output, Display, Analog Output etc to Electronic Switching device (ETD). Also, CAN nodes are able to distinguish short disturbances from permanent failures. Defective node declares itself logically disconnected from the network. This stage called bus offstage, in this stage node do not have any influence on CAN bus.
Other extremely important features of the controlled area network are that it offers features like auto Error detection, Automatic CRC computation and Automatic retransmission of corrupt message. This feature in CAN saves additional burden on CPU. Reference herein is being given to Figure 1 and Figure 2 that describes one of the embodiments of the present invention in which a communication system for an electrical interruption means comprises of an electronic tripping device 10, an application specific preprogrammed module 12 configured to the electronic tripping device 10, a controller area network including a defined communication protocol and a communication bus 14. The controller area network enables the electronic tripping device 10 to communicate with the application specific preprogrammed module 12 via the communication bus 14. Further, a microcontroller (not shown) monitors and controls data flow between the


electronic tripping device 10 and the module 12. The Microcontroller is part of Electronics tripping device or Module. Each module has one microcontroller. And Electronics Tripping device has one microcontroller.
It is to be noted and as referred in Figure 2, the preprogrammed module 12 further comprises of an application layer 16 and a transport layer 18 wherein the transport layer 18 is same to each of the plurality of modules 12. The electronic tripping device 10 also has a preinstalled application layer 16 and transport layer 18.
Normally, for the electronic tripping device 10 and the module(s) 12 software architecture is preinstalled and is divided in two layers. First layer is the application layer 16, which handles module 12 specific functionalities while the second layer is the transport layer 18, which handles functionalities like data transmission, hot plug-in, error handling in communication with modules 12. In present embodiment all modules 12 have same software for transport layer 18 and the ETD 10. Software developed for one module 12 can be easily used for rest of modules 12.
Transport layer 18 offer various application program interface (API) 17 to application layer 16 for data transmission and error checking. Application layer 16 and Transport layer 18 share common transaction buffer 19 for data exchange. Transport layer 18 of every module 12 update data in transaction buffer while the application layer 16 receives data in predefine format and takes actions accordingly by analyzing the received data.


Every module 12 has different parameter and software requirement. So module 12 dependent parameters like crystal frequency, maximum no of bytes in transaction buffer etc. are defined in common header file between transport layer 18 and application layer 16. Unique software architecture reduces development and testing efforts. ETD 10 and module 12 share common transport layer 18. Every module 12 and ETD 10 has different application layer 16 depending on its functionality.
Now as shown in Figure 3, the controller area network (CAN) protocol does not support transmission of more than 64 bits in one frame. Modules 12 may have larger information, which can not be transmitted to ETD 10 in single 8 byte frame. So transport layer 18 needs to divide information in to frame of 8 bytes. In the present embodiment transmission and reception of data is up to 255 bytes.
To send data on the CAN bus 14, transmitter (ETD 10 or module 12) will inform the recipient the total no of bytes to be sent in first frame. Total frame to be sent or receive will be calculated on both ETD 10 (master) and module 12 (slave) on basis of total number of bytes. The receiver will keep a local track on the number of frames expected and compare them with those received frame (shown in Figure 3).
Data in transaction buffer divided into frames of 8 bytes or less. Each frame contains 6 bytes of data to be sent and the additional two bytes of frame number inserted by the transport layer 18. First frame contains number of bytes and data bytes. Consecutive


frame will follow the first frame. In the last frame "Transport layer 18 Control Byte" are appended, which consist of control bits. After receiving all consecutive frames the receiver will send the flow control acknowledge message for error or successful reception of all frames. For error code reception transmitter will resend data to receiver.
If maximum data byte to be sent is more than predefine limit, then data will be divided in to packet by the application layer 16. Application layer 16 of receiver will keep track of multiple packet and process data. Maximum data byte supported by transport layer is predefine common header file (Between Application layer and transport layer).
According to one embodiment of the present invention and as illustrated in fig 4, in the communication protocol of the controller area network 20, data flow is prioritized between the plurality of modules 12 configured to the electronic tripping device 10 wherein the prioritization of data between the modules 12 depends on a unique module ID assigned to each of the module 12. It is quite well known that data on bus 14 might get corrupt due to the electromagnetic waves generated by the noise produced while in industrial operation. The problem occurs when the two modules 12 start transmitting data in the form of messages simultaneously. This condition creates loss of time window. Data transmission in ETD 10 required message arbitration for efficient communication between modules 12 and ETD 10. As CAN have facility of message arbitration, if two messages are simultaneously sent over the CAN bus 14, the bus 14 takes the "logical AND" of all them. The messages identifier with the lowest binary number gets the


highest priority. Every device listens on the channel and backs off as and when it notices a mismatch between the bus's bit and its identifier's bit. This feature provides message arbitration without loss of time window. This feature reduce additional burden on CPU which may not have been the case with traditional microcontroller. According to another embodiment of the present invention and as illustrated in Fig 3, a system for automatic detection of a module 12 with an electrical interruption means comprises of an electronic tripping device 10 for sending messages to a non-configured application specific preprogrammed module 12 coupled to the electronic tripping device 10, a controller area network including a defined communication protocol and a communication bus 14, the controller area network enabling the electronic tripping device 10 to communicate with the non-configured application specific module 12 via the communication bus 14, wherein the electronic tripping device 10 interrogates the module 12 by sending broadcast message followed by configuration data and ping request to which reciprocal of the module 12.
CAN protocol does support automatic module 12 detection facility. Automatic module 12 detection is service to detect non-configured devices which are already connected on CAN bus 14. To detect modules 12 connected on CAN bus 14, ETD 10 (master) will send broadcast message (data) 22 to all modules 12 connected on CAN bus 14. This broadcast message is transmitted at predefine interval. After reception of "Broadcast message" all modules 12 will reply 24 with their predefined module IDs to join networks. ETD 10 will receive 26 this data and give permission 28 to modules 12 to join network.


At time of joining process master will send addresses and configuration data to module 12. On successful joining master will update list of connected modules 12.
To avoid collision on CAN bus 14 all different type of modules 12 will have offset time according to their module IDs. Once any module 12 is successfully configured, module 12 will stop responding to "Broadcast Message".
After configuration master send ping request 30 at predefine interval to every module 12. If module 12 does not have predefined data to send it to master, module 12 responds with empty message 32 (header and 0 data bytes). If master do not receive response of ping request for predefine period, it declare communication error for respective module 12. On communication error master remove module 12 from its list of module 12 connected.
Figure 3 shows network join process for module 1 and module 2. On the reception of broadcast message module 1, module 2 and module 3 are sending hot plug in message. ETD 10 receives data from all three modules 12 and processes it. And give permission to module 1 and module 2 to join network, by sending addresses and configuration data. ETD 10 will not send address and configuration data to module 3, due to invalid data in hot-plug in message. This feature prevents unauthorized access of network.
The foregoing description of the invention has been described for purposes of clarity and understanding. It is not intended to limit the invention to the precise form disclosed.


Various modifications may be possible within the scope and equivalence of the appended claims.


CLAIMS
What is claimed is:
1. A communication system for an electrical interruption means, the system
comprising:
an electronic tripping device;
an application specific preprogrammed module configured to the electronic tripping device;
a controller area network including a defined communication protocol and a communication bus, the controller area network enables the electronic tripping device to communicate with the application specific preprogrammed module via the communication bus; and
a microcontroller for monitoring and controlling data flow between the electronic tripping device and the module.
2. The communication system as claimed in claim 1 further comprising a
plurality of modules configured to the electronic tripping device.


3. The communication system as claimed in claim 2, wherein in the
communication protocol of the controller area network, data flow is prioritized
between the plurality of modules configured to the electronic tripping device.
4. The communication system as claimed in claim 3, wherein the prioritization of data between the modules depends on a unique module ID.
5. The communication system as claimed in claim 1, wherein the data flow between the electronic tripping device and the module is processed in small packets via the communication bus.

6. The communication system as claimed in claim 1, wherein in the communication protocol of the controller area network corrupt data is automatically retransmitted between the module and the electronic tripping device.
7. The communication system as claimed in claim 1, wherein in the communication protocol of the controller area network error between the module and the electronic tripping device is automatically detected.
8. The communication system as claimed in claim 1, wherein the module is
digital input/ output device, display unit, analog output or the like.


9. The communication system as claimed in claim 1, the preprogrammed module
further comprises of an application layer and a transport layer.
10. The communication system as claimed in claim 1, the electronic tripping device has a preinstalled application layer and transport layer.
11. The communication system as claimed in claim 1, wherein the transport layer is same to each of the plurality of modules.
12. The communication system as claimed in claim 1, wherein the
Microcontroller is part of electronics tripping device or module wherein each
module has one microcontroller, and electronics tripping device has one
microcontroller.
13. A system for automatic detection of a module with an electrical interruption
means, the system comprising:
an electronic tripping device for sending messages to a non-configured application specific preprogrammed module coupled to the electronic tripping device;


a controller area network including a defined communication protocol and a communication bus, the controller area network enabling the electronic tripping device to communicate with the non-configured application specific module via the communication bus; wherein
the electronic tripping device interrogates the module by sending broadcast message followed by configuration data and ping request to which reciprocal of the module.
14. The system as claimed in claim 13, wherein the electronic tripping device sends messages to a plurality of modules.
15. The system as claimed in claim 13, wherein firstly, the electronic tripping device sends data in the form of broadcast message to the module to which the module replies by sending pre-assigned module ID.
16. The system as claimed in claim 13, wherein secondly, on receiving the module ID the electronic tripping device sends permission in the form of configuration data to be received by the module.
17. The system as claimed in claim 13, wherein thirdly, the electronic tripping device send ping request to the module.


18. The system as claimed in claim 13, wherein the electronic tripping device send ping request to the plurality of modules.
19. The system as claimed in claim 13, wherein the electronic tripping device declares a communication error if it does not receives a response from the module for a predetermined specific period of time thereby detecting non-configuration of the module.





ABSTRACT
A communication system for an electrical interruption means, the system comprising an electronic tripping device an application specific preprogrammed module configured to the electronic tripping device, a controller area network including a defined communication protocol and a communication bus, the controller area network enables the electronic tripping device to communicate with the application specific preprogrammed module via the communication bus, and a microcontroller for monitoring and controlling data flow between the electronic tripping device and the module.
19 Claims, 4 Drawing Sheets