Claims:1. A method for communicating plurality of protection setting updates from at least one slave device to at least one master device in an electrical switching device, said method comprising:
receiving, by an user interface, at least one input corresponding to said protection setting updates provided by said slave device;
storing, in at least one memory unit in said slave device, said input;
enabling a reset sequence of said slave device and thereby actuating a Pre-RAM initialization process whereby:
first the variables related to non-volatile memory reading of settings and communication are initialized, followed by
configuration of communication peripherals and ports for communication; and communication of said protection setting update from said slave device to said master device takes place after reading said protection setting updates from said memory unit according to a counter value;
transmitting, by said slave device, said protection setting update to said master device within a time period of 16-18 ms, and then enabling, by said slave device, RAM/ROM memory initialization process to initialize remaining variables in said slave device.

2. The method as claimed in claim 1, wherein the reading of the settings according to the counter value from the non-volatile memory takes less than approximately 1ms.

3. The method as claimed in claim 2, wherein the reading of the settings is followed by the transmission of data from the display controller to main controller taking about 2-3 ms.

4. The method as claimed in claim 1, wherein the RAM/ROM initialization process optionally comprising initialization of variables for providing user interface such as initialization of variables for storing and display of metering, records data, configuring the display driver for displaying the data, configuring the navigation key port pins for taking input from the user and the like.

5. The method as claimed in claim 4, wherein the RAM/ROM initialization process further comprising configuration of LED’s, display backlight for system healthiness or fault indication purposes.

6. The method as claimed in claim 1, comprising:
receiving, by said user interface, said input corresponding to said protection setting update in online or offline mode, wherein said online mode corresponds to power ON condition and said offline mode corresponds to power OFF condition of said master or main controller device.

7. The method as claimed in claim 1, wherein said master device is a main controller unit.

8. The method as claimed in claim 1, wherein said slave device is a display controller unit.

9. The method as claimed in claim 1, wherein said inter-controller communication between said master device and said slave device is performed using at least serial protocol bus.

10. The method as claimed in claim 1, comprises:
storing, by said memory unit in said slave device, said input in the form of frames and one or more cyclic redundancy check code (CRC) at each frames to validate data on reading said frames.

11. The method as claimed in claims 1-10, wherein the step of transmitting said protection setting update from said slave device to said master device within a time period of 16-18 ms comprises:
reading, by said slave device, said protection setting updates in the form of a frame, one by one from said memory unit based on said counter value, wherein said counter value incremented at the end of reading each said frame;
converting, by said slave device, said frames into a communication frame format;
sending, by said slave device using at least one signal, at least one clock request message to said master device;
receiving, by said slave device, said clock from said master device and thereby transmitting, by said slave device, said frames one by one to said master device;
sending, by said master device, at least one acknowledgement message to said slave device upon receiving said frames.

12. The method as claimed in claim 11, comprising:
receiving, by said master device, said protection setting updates from said slave device for subsequent processing, wherein said master device performs tripping of said electrical switching device according to said protection setting updates.

13. An electronic switching device adapted to perform the method as claimed in claims 1-12, said electronic switching device comprising:
at least one electronic trip unit provided with at least one display unit for user interface;
at least one display driver;
at least one main controller unit;
at least one display controller unit; and
at least one bus interface;
wherein, said display controller unit configured to:
receive, by said display unit, at least one input corresponding to said protection setting update and thereby enable a pre-initialization process for initializing one or more variables related to communication of said protection setting update from said display controller unit to said main controller unit;
transmit, by said bus interface, said protection setting update to said main controller unit within a time period of 16 to 18 ms;
and then enable RAM/ROM memory initialization process to initialize remaining variables in said display controller unit.

14. The electronic switching device as claimed in claim 13, wherein said main controller unit is configured as master and said display controller unit is configured as slave.
15. The electronic switching device 13, wherein said bus interface is provided by serial peripheral interface protocol or I2C protocol or any combination thereof.
16. A slave device in an electrical switching device as claimed in claims 13-16, wherein said slave device comprising:
at least one display unit to receive at least one input corresponding to protection setting update;
at least one memory unit to store said input in the form of frames;
at least one processing unit configured to enable said slave device to:
read said frames one by one from said memory unit;
perform pre-initialization process for initializing one or more variables related to communication of said frames from said slave device to said master device;
transmit, by means of at least one bus interface, said frames from said slave device to at least one master device; and then
enable RAM/ROM memory initialization process in said slave device to initialize remaining variables in said slave device;
wherein said slave device enable communication of said protection setting update to said master device within a time period of 16 to 18 ms.
, Description:TECHNICAL FIELD

[001] The present subject matter described herein, in general, relates to a method of communication between two controller units in an electrical switching devices, and more particularly, relates to an improved method for communication of protection settings update between master device and a slave device in an electronic trip unit of circuit breakers.

BACKGROUND

[002] The Circuit breakers or electronic tripping unit (ETU) provide a variety of protections with the use of microcontrollers for fault sensing and giving trip command. It enables breaking of current passing through an electrical circuit, in case the current goes above a certain threshold value. These ETU provides a variety of protections that may include but not limited to current protection, voltage protection, frequency protection and the like. Settings of the various protections offered can be preset through rotary switch, dip switches, and display navigation. Circuit breakers can provide energy, current, voltage, frequency metering and can also communicate on network (SCADA, HMI) using protocols such as CAN bus, MODBUS.

[003] As the features increases, generally different controllers are used to perform different activities in the trip unit. Data thus generated in one controller needs to be shared between various controllers. For example, one microcontroller may be used to perform breaker critical operations that may include but not limited to fault sensing, giving trip command to the breaker in case of fault, generating trip records, calculating metering data and the like. Whereas another microcontroller may be used for providing user interface such as display navigation. Display navigation can be used to view/change various protection settings, view trip record data, metering data and the like. Since, data is generated in main controller; it needs to be communicated to the display controller so that user can view various parameters as and when required. Also, parameters such as protection settings or trip record can be viewed by the user even after power down. So these parameters are generally stored in non-volatile memory such as data flash, which are subsequently processed.

[004] Circuit breakers offer various types of protections and all these protection have different settings such as pickup value, delay, and the like. All the protection settings are configurable via display navigation. As user interface is handled by display controller and fault sensing and tripping command by main controller, so these settings needs to be communicated to the main controller as and when changed by the user. Many times these settings can be changed by user in offline mode also, that is when main controller is not powered up. Hence, in such case, display controller needs to sense that main controller is powered up and send new settings to main controller.

[005] Reference is made to US 7,948,343 B2, wherein a settings emulator for a circuit breaker trip unit includes a handheld enclosure and a plurality of adjustable rotary switches mounted on the handheld enclosure. The adjustable rotary switches define a plurality of different trip settings for the circuit breaker trip unit. A communication channel is also mounted on the handheld enclosure. A microprocessor is enclosed by the handheld enclosure. The processor reads the different trip settings from the adjustable rotary switches and communicates the different trip settings through the communication channel to the circuit breaker trip unit.

[006] However, the US ‘343 B2 discusses about a handheld enclosure for changing protection settings of circuit breaker and communicating the same to the trip unit via wired/wireless communication. But since the settings emulator is a separate device other than trip unit and requires communication interface means to communicate with trip unit it adds to the cost of the entire unit. Also the entire setup doesn’t remain compact.

[007] Reference is made to US 8,654,496 B2, wherein a communication adapter module (CAM) which saves a copy of trip unit settings and is separable from the trip unit is disclosed. This module can communicate with the trip unit using various protocols and in case the trip unit fails, this module can be separated from the trip unit and the same settings can be communicated to another trip unit. Thus in case of replacing other trip unit, manually the settings need not be changed. CAM module can be used to dump the settings.

[008] In electronic trip units, data generated in one controller needs to be communicated to another one is a time critical activity. For example when any of the protection settings are changed by the user in offline mode, it will be saved in non-volatile memory of the display controller, but cannot be communicated to the main controller instantly since main controller is powered OFF. In case of short circuit or instantaneous fault, trip time may be as less as 20ms. Also, the fault may happen during make ON condition of the breaker. In this case it is important that main controller, that is responsible for fault sensing and giving trip command works with the latest settings done by the user. Hence it is critical to communicate the protection settings from display controller’s non-volatile memory to the main controller before the minimum possible trip time.

[009] The existing controller usually have a power up sequence which includes reset sequence, RAM/ROM initialization, peripheral initialization and then actual processing starts. Depending on the controller, reset sequence may take from few us to ms typically of the order of 1 to 3ms. After that RAM/ROM initialization takes place, which may take 6-7 ms depending upon the number of variables. Hence actual communication of settings will start after 8- 10ms from power up. Since, some of the protections have very less trip time, for example in case of short circuit fault, trip time can be as less as 20ms. Therefore, upon considering the above power up sequence of the existing controller, it may take much more time to communicate the settings from display controller to main controller at power up.

[0010] Hence, there exists a need to device an efficient method to communicate all the protection settings information from display controller to the main controller within minimum possible trip time period from power up so as to take care of short circuit and instantaneous make on fault.

SUMMARY OF THE INVENTION

[0011] 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.

[0012] An object of the present invention is to provide a method for communicating protection setting update between two controllers in electronic trip unit of circuit breakers such that one controller generates the data and is responsible for fault sensing whereas other controller stores the data generated by first controller and provides user interface.

[0013] Another object of the present invention is to provide a reliable protection settings communication between two controllers in the electronic trip unit using Pre- initialization process and inter-controller communication is disclosed.

[0014] Yet another object of the present invention is to provide a method for communicating protection setting update from a slave device to a master device within a time period of 20ms from power up.

[0015] Accordingly to one aspect, the present invention provides a method for communicating plurality of protection setting updates from at least one slave device to at least one master device in an electrical switching device, said method comprising:

• receiving, by means of an user interface, at least one input corresponding to said protection setting updates provided by said slave device;
• storing, by using at least one memory unit in said slave device, said input;
• enabling a reset sequence of said slave device and thereby actuating a Pre-RAM initialization process whereby:
first the variables related to non-volatile memory reading of settings and communication are initialized, followed by
configuration of communication peripherals and ports for communication; and communication of said protection setting update from said slave device to said master device takes place after reading said protection setting updates from said memory unit according to a counter value;
• transmitting, by said slave device, said protection setting update to said master device within a time period of 16-18 ms, and then enabling, by said slave device, RAM/ROM memory initialization process to initialize remaining variables in said slave device.

[0016] In second aspect, the present invention provides an electronic switching device operating the method as mentioned above, said electronic switching device comprising: at least one electronic trip unit provided with at least one display unit for user interface; at least one display driver; at least one main controller unit; at least one display controller unit; and at least one bus interface, wherein, said display controller unit configured to:
• receive, by said display unit, at least one input corresponding to said protection setting update and thereby enable a pre-initialization process for initializing one or more variables related to communication of said protection setting update from said display controller unit to said main controller unit;
• transmit, by said bus interface, said protection setting update to said main controller unit within a time period of 16 to 18 ms;
• and then enable RAM/ROM memory initialization process to initialize remaining variables in said display controller unit.

[0017] In third aspect, the present invention provide a slave device in an electrical switching device, wherein said slave device comprising: at least one display unit to receive at least one input corresponding to protection setting update; at least one memory unit to store said input in the form of frames; at least one processing unit configured to enable said slave device to:
• read said frames one by one from said memory unit;
• perform pre-initialization process for initializing one or more variables related to communication of said frames from said slave device to said master device;
• transmit, by means of at least one bus interface, said frames from said slave device to at least one master device; and then enable RAM/ROM memory initialization process in said slave device to initialize remaining variables in said slave device;
Wherein, said slave device enable communication of said protection setting update to said master device within a time period of 16-18 ms.

[0018] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0019] Figure 1 illustrates a block diagram representation of a main controller unit and display controller unit using a serial communication protocol, in accordance with an embodiment of the present invention.
[0020] Figure 2 illustrate a block diagram representation of a main controller unit and display controller unit and mainly instructing the signals used for communication, in accordance with an embodiment of the present invention.
[0021] Figure 3 illustrates flow chart indicating the steps for communicating protection setting updates from a display controller unit to a main controller unit, in accordance with an embodiment of the present invention.

[0022] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0023] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0024] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0025] The terms and words used in the following description and claims 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 as defined by the appended claims and their equivalents.

[0026] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0027] 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.

[0028] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0029] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0030] It is also to be understood that the term “module” is used in the specification to indicate an apparatus, unit, component and the like. The term “means” when used in the specification is taken to specify the mode by which desired result is achieved.

[0031] The present invention can be implemented with an electrical switching system that may include but not limited to, circuit breakers or thermo-magnetic breaker, molded case circuit breaker (MCCB) residual circuit breaker (RCB), earth leakage circuit breaker (ELCB) and the like. In one implementation, the controller unit used in the present invention can be a microcontroller.

[0032] In the present invention, a time bound and reliable method of communication of protection settings from a slave device to a master device is provided wherein the master device is a main controller unit and the slave device is a display controller unit in an electrical switching device. Since the reset sequence timing in the controller can’t be reduced as it is controller specific, therefore, the present invention achieves the objective by splitting the RAM initialization process into two parts such that only variables related to settings communication are initialized first. This process is called as pre-initialization process. Thus, in the present invention, actual RAM initialization takes place after protection settings communication. Also, in the present invention enables initialization of only those peripherals at power up which are required for settings communication and rest peripherals can be initialized as and when required.

[0033] Typically, RAM initialization takes time according to the number of variables in the module. In one implementation, the RAM initialization time can reduced by initializing only those variables which are used for communicating the protection settings before actual RAM/ROM memory initialization. The RAM/ROM initialization process optionally comprising initialization of variables for providing user interface such as initialization of variables for storing and display of metering, records data, configuring the display driver for displaying the data, configuring the navigation key port pins for taking input from the user and the like. The RAM/ROM initialization process further comprising configuration of LED’s, display backlight for system healthiness or fault indication purposes.

[0034] It is understood that the master and slave devices are controller units, each comprising a display, a memory unit storing instructions and a processor executing said instructions to enable said master and slave devices to perform communication of data.

[0035] In one implementation, the figure 1 is a block diagram of the integrated circuits, more specifically circuit breakers, Electronic trip unit (ETU) with LCD display for user interface, comprising main controller, display controller, LCD display driver and bus interface. In one implementation, the bus interface can be provided by SPI protocol. Even I2C could be used for the purpose. The SPI protocol in general uses 4 wires (Master In Slave Out MISO, Master Out Slave In MOSI, Clock, Slave select).

[0036] In one implementation, as shown in figure 2, single master and single slave communication can be used for communication. Here the main controller is configured as master and display controller is configured as slave device. As main controller is the master, so clock for communication is controlled by the master.

[0037] In one implementation, the main controller senses the fault and issues trip command when current goes above a certain threshold. User interface for receiving at least one input that may include but not limited to changing settings, viewing trip record, viewing metering data can be provided by the display controller. The settings of various protections can be changed both in online and offline mode wherein the online mode corresponds to mode in which both main controller and display controller are powered ON. When the protection settings will be changed in online mode by the user, settings will be saved in non- volatile memory of the display controller and will be communicated to the main controller instantly. Whereas in offline mode, only display controller is powered UP, so when settings are changed in offline mode, then settings will only be saved in the non-volatile memory of the display controller but cannot be communicated to the main controller. In this case, settings can be communicated only when online power up happens.

[0038] In one implementation, the settings received by the user interface are stored in the non-volatile memory such as data flash memory of display controller. Hence, before communicating the settings from display controller to main controller, these settings need to be read from the data flash. The protection settings are stored in the non-volatile memory in the form of frames wherein each frame may be of current protection, another of voltage protection, and the like, and at the end of each frame cyclic redundancy check code (CRC) may be stored so as to validate the data on reading the frame.

[0039] In one implementation, reference is made to figure 3, wherein the process for the communicating protection settings from the slave device to the slave device is illustrated. Protocol chosen as an example for inter-controller communication can be SPI (Serial Peripheral Interface), but same can be achieved using other protocols as well. First the controller executes the reset sequence. Then various controller ports can be configured according to the requirement. Next step is to configure the SPI peripheral for communication. Then Pre-RAM initialization of variables required for communication of various protection settings from display controller to main controller is done. The settings stored in the data flash memory are read based on a settings counter value which is incremented at the end of each settings are read. Thus first the protection settings frames may be read one at a time from the display controller memory. Then before communication takes place, frames can be converted to communication frame format. Once communication frame is ready for transmission, the slave device (display controller) requests for clock from master device by using a handshaking signal. On reception of clock from the master the slave may send frames that is current protection first. On reception of settings frame, master sends the acknowledgement to the slave device. The process continues till all the settings frame are sent to the master device. Thus all settings will be communicated to the master (main controller) within a time period of 16-18ms from power up. After all the frames are sent to the master, then RAM initialization for remaining variables to be used in the slave device is done. After RAM initialization is complete remaining peripherals are initialized.

[0040] In one implementation the reading of the settings according to the counter value from the non-volatile memory takes less than approximately 1ms.

[0041] In one implementation, the reading of the settings is followed by the transmission of data from the display controller to main controller taking about 2-3 ms.

[0042] In one implementation, the master device (main controller unit) receives the protection setting updates from the slave device for subsequent processing, wherein said master device performs tripping of the electrical switching device according to the protection setting updates.

[0043] Some of the advantages of the present invention, are as follows:
• Efficient method of communicating protection settings from display controller to main controller within 16-18 ms from power up thus making the new settings available before tripping in case of make ON fault.
• Unique pre-RAM initialization process and inter controller communication process for protection settings communication.

[0044] Although a method for communication of protection settings in a circuit breaker have 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 of the method for communication of protection settings in a circuit breaker.