Patent Publication Number: US-2001000355-A1

Title: Electronic trip unit having software download capabilities

Description:
RELATED APPLICATIONS  
     1. This application is a continuation-in-part of U.S. patent application Ser. No. 09/221,243 filed Dec. 28, 1998, which is incorporated by reference herein.  
    
    
     
       BACKGROUND OF THE INVENTION  
       2. The present invention relates generally to electronic trip units. More specifically, the present invention relates to electronic trip units having software download capabilities.  
       3. Electronic trip units (trip units) for actuating the separable contacts in a circuit breaker are well known. An electronic trip unit typically comprises voltage and current sensors that provide analog signals indicative of the power line signals. The analog signals are converted by an A/D (analog/digital) converter to digital signals that are processed by a microcontroller. The trip unit further includes RAM (random access memory), ROM (read only memory) and EPROM (electronic programmable read only memory) all of which interface with the microcontroller. The ROM includes trip unit application code, e.g., main functionality firmware, including initializing parameters, boot code, and operational parameters. Operational parameters for the application code are also stored in the EPROM. An output of the electronic trip unit actuates separable contacts of the circuit breaker. When the contacts open, circuit current is prevented from flowing from one contact member to the other and therefore, circuit current is prevented from flowing to a load which is connected to the breaker. The electronic trip unit initiates a trip for instantaneous, short time, long time, ground fault and manual conditions.  
       4. The inventors have discovered a need in the industry for upgradeable or adjustable trip units and have found that the use of EPROM technology has prevented trip units from being upgradeableCa desirable feature to drive service growth in the trip control industry.  
       BRIEF SUMMARY OF THE INVENTION  
       5. To overcome the limitations of the prior art, non-volatile memory such as EEPROM (Electrically Erasable Programmable Read Only Memory) or Flash memory is provided in the trip unit for storing the firmware, enabling one to change the trip unit&#39;s firmware after it is manufactured. The present invention provides increased functionality to trip units by enabling upgrades and servicing of the trip unit by downloading firmware to it. This would include remotely downloading firmware when the electronic trip unit is connected to a host controller, such as a multi-purpose computer either directly, over the telephone lines, LAN or any other suitable connection such as the Internet.  
       6. The above discussed and other features and additional advantages of the present invention will be appreciated and understood by those skilled in the art from the detailed description and drawings.  
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     7.FIG. 1 is a schematic block diagram of an electronic trip unit of the present invention; and  
     8.FIG. 2 is a schematic block diagram showing the trip unit&#39;s interconnectivity with a host controller and server via the Internet.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     9. Copending U.S. patent application Ser. No. 09/221,243 filed Dec. 28, 1998, is hereby incorporated in full herein by reference.  
     10. Referring to FIG. 1, a general schematic of an electronic trip unit of the present invention is generally shown at  30 . Power passes along power lines  10  to load  20 . Circuit breaker contacts  57 , shown in the open position are normally in the closed position so that power can pass to load  20 . Voltage sensor  32  and current sensor  36  provide analog signals indicative of a voltage and current measurements on signal lines  38  and  34 , respectively. The invention is not limited to requiring that both voltage and current sensors be present, but instead contemplates that either type of sensor, or any other sensor capable of sensing a fault condition of load  20  may be employed.  
     11. The analog signals on lines  34  and  38  are presented to an A/D (analog/digital) converter  40 , which converts these analog signals to digital signals. The digital signals are transferred over datapath  42  to a microcontroller (microprocessor or signal processor)  44 , such being commercially available from the Hitachi Electronics Components Group (Hitachi s H8/300 family of microcontrollers). Trip unit  30  further includes RAM (random access memory)  46 , ROM (read only memory)  48  and EEPROM (electronic erasable programmable read only memory) or flash memory (including sector erasable flash memory)  50  all of which communicate with the microcontroller  44  over a control bus  52 . It will be appreciated that A/D converter  40 , ROM  48 , RAM  46 , or any combination thereof may be internal to microcontroller  44 , as is well known. EEPROM  50  is non-volatile so that system information and programming will not be lost during a power interruption or outage. Data, typically status of the circuit breaker, is displayed by a display  54  in response to display signals received from microcontroller  44  over control bus  52 . An output control device  56 , in response to control signals received from microcontroller  44  over control bus  52 , controls a trip module  58  via a line  60 .  
     12. The EEPROM or flash memory includes trip unit application code and software settings, including initializing parameters, operational parameters such as the trip curve, and boot code. The firmware is initially stored in the electronic trip unit at the factory and can be downloaded or flashed for firmware upgrades and servicing. This would include remotely downloading the firmware when the electronic trip unit is connected to a system computer (not shown), either directly, over the telephone lines, or any other suitable connection. It may also be preferred that EEPROM  50  comprises a flash memory whereby such data is flashed, as is well known. During boot up of the electronic trip unit the firmware stored in the EEPROM, in particular the executable code, is loaded into the working memory, i.e., the RAM. This allows the processor to continue operating while the EEPROM or Flash is being updated. The firmware defines trip unit operation, including trip curve characteristics such as instantaneous, short time, long time, ground fault trip.  
     13.FIG. 2 shows an exemplary embodiment for downloading firmware to trip unit  30 . In this embodiment, multiple trip units  30  are connected via local area network  72  to host controller  77  which may be configured for monitoring the status of the trip units  30 . Additional trip units (not shown) may be connected using connections  73 . Host controller  77  is capable of downloading firmware to trip units  30  directly by the end users, or at the direction of remote computer  70  via the Internet  75 . In this configuration, remote computer  70  can also be configured to monitor the trip units&#39; status which can permit a centralized or outsourced monitoring of the industrial systems and also allows servicing of trip units  30  by persons in a remote location, which can reduce down time and expense necessary to get expert personnel to the location when servicing is required.  
     14. While preferred embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Accordingly, it is to be understood that the present invention has been described by way of illustrations and not limitation.