Load analysis system for fault detection

A method of analyzing faults occurring on a distribution circuit coupled to an AC power source, comprising the steps of:

• monitoring a load current flowing over the distribution circuit during sequential time analysis units and generating in response thereto a stream of incoming load current data values for each time analysis unit;
• initially storing a first stream of load current data values in a first data storage location;
• storing a second subsequent stream of load current data values in a second data storage location;
• checking each data value of the second stream for any abnormality;
• when all of the data values in the second stream are found to be normal during the checking step, updating the data values stored in the first location with the data values stored in the second location;
• when an abnormal data value is found during the checking step, storing the most recent normal data in the first location by replacing the oldest portion of the data values stored in the first location with the data from the second stream which precede the abnormal data value, and storing the post abnormality data in the second location;
• analyzing the load current over time;
• and
• distinguishing, based on the analysis of the load current, the difference between a first type of fault requiring de-energization of the distribution circuit, and a second type of fault for which the distribution circuit remains energized.

A method of analyzing faults occurring on a distribution circuit coupled to an AC power source, comprising the steps of:

• monitoring a load current flowing over the distribution circuit;
• analyzing the load current over time for plural types of conditions;
• and
• distinguishing, based on the analysis of the load current, the difference between a first type of fault requiring de-energization of the distribution circuit, and a second type of fault for which the distribution circuit remains energized, where the distinguishing step includes the steps of initiating plural timers, checking several of the plural types of conditions while the timers are running, and selectively providing alarms, downed conductor, and arcing outputs.

A load analysis apparatus for analyzing faults occurring on a distribution circuit coupled to an AC power source, comprising:

• a monitor for monitoring a load current flowing over the distribution circuit and in response thereto, generating a load signal, the monitor including a transducer coupled to the distribution circuit to indicate the load current magnitude and waveform;
• a controller responsive to the monitor for analyzing the load current over time, and for distinguishing from the analyzed load current the occurrence of a first type of fault requiring de-energization of the distribution circuit, and of a second type of fault for which the distribution circuit remains energized;
• and
• a surge protector for protecting the load analysis apparatus from surges on the distribution circuit.