Apparatus and method for seamlessly upgrading the firmware of an intelligent electronic device

An IED comprising:

• a power monitoring circuit operative to monitor a parameter of a portion of a power distribution system and generate an analog signal representative thereof;
• an analog to digital converter coupled with said power monitoring circuit, said analog to digital converter operative to convert said analog signal to a digital signal representative thereof;
• a processor coupled with said analog to digital converter and operative to implement power management functionality and generate power management data;
• at least one of a display and a communications interface coupled with said processor and operative to communicate said power management data external to said IED;
• an interface coupled with said processor and operative to receive an external function module;
• wherein said IED further comprises a first non-volatile memory operative to store first program code for execution by said processor, said processor being operative to access a second non-volatile memory in said external function module via said interface, said second non-volatile memory comprising second program code, said processor further operative to replace said first program code in said first non-volatile memory with said second program code.