A trip unit for a circuit interrupter for a power circuit, said circuit interrupter including an operating mechanism and separable contacts, said trip unit comprising: a trip circuit structured to cooperate with said operating mechanism to trip open said separable contacts, said trip circuit comprising a number of hardware circuits (16, 18, 20, 22, 24, 26, 28, 30, 32, 34) including a processor having a number of routines (38,40,42) structured to provide: a number of protective functions structured to detect a number of faults of said power circuit, a number of repetitive test functions for said number of hardware circuits (16, 18, 20, 22, 24, 26, 28, 30, 32, 34), and a supervisory function cooperating with said number of repetitive test functions, said supervisory function being structured to prevent availability of protection by said number of protective functions from falling below a predetermined threshold as a result of a plurality of intermittent error conditions of said number of hardware circuits (16, 18, 20, 22, 24, 26, 28, 30, 32, 34), wherein said supervisory function is executed once per each of a plurality of half-cycles of a line-to-neutral voltage of said power circuit, and is structured to determine if any one of the number of repetitive test functions detects an error condition during a current one of the half-cycles, set a timer equal to a predetermined timeout value if the error condition is detected during the current one of the half-cycles, irrespective whether or not the error condition is detected and the timer is set or not to the predetermined timeout value, determine if the timer is greater than zero or not, decrement the timer and increment an accumulator if the timer is greater than zero, reset the accumulator if the timer is not greater than zero, and determine if the accumulator is greater than a predetermined threshold value and responsively cause said trip circuit to cooperate with said operating mechanism to trip open said separable contacts. a trip circuit structured to cooperate with said operating mechanism to trip open said separable contacts, said trip circuit comprising a number of hardware circuits (16, 18, 20, 22, 24, 26, 28, 30, 32, 34) including a processor having a number of routines (38,40,42) structured to provide: a number of protective functions structured to detect a number of faults of said power circuit, a number of repetitive test functions for said number of hardware circuits (16, 18, 20, 22, 24, 26, 28, 30, 32, 34), and a supervisory function cooperating with said number of repetitive test functions, said supervisory function being structured to prevent availability of protection by said number of protective functions from falling below a predetermined threshold as a result of a plurality of intermittent error conditions of said number of hardware circuits (16, 18, 20, 22, 24, 26, 28, 30, 32, 34), a number of protective functions structured to detect a number of faults of said power circuit, a number of repetitive test functions for said number of hardware circuits (16, 18, 20, 22, 24, 26, 28, 30, 32, 34), and a supervisory function cooperating with said number of repetitive test functions, said supervisory function being structured to prevent availability of protection by said number of protective functions from falling below a predetermined threshold as a result of a plurality of intermittent error conditions of said number of hardware circuits (16, 18, 20, 22, 24, 26, 28, 30, 32, 34), wherein said supervisory function is executed once per each of a plurality of half-cycles of a line-to-neutral voltage of said power circuit, and is structured to determine if any one of the number of repetitive test functions detects an error condition during a current one of the half-cycles, set a timer equal to a predetermined timeout value if the error condition is detected during the current one of the half-cycles, irrespective whether or not the error condition is detected and the timer is set or not to the predetermined timeout value, determine if the timer is greater than zero or not, decrement the timer and increment an accumulator if the timer is greater than zero, reset the accumulator if the timer is not greater than zero, and determine if the accumulator is greater than a predetermined threshold value and responsively cause said trip circuit to cooperate with said operating mechanism to trip open said separable contacts.