Energy Algorithm; Randomness Algorithm; Expert Arc Detector Algorithm - GE F60 Instruction Manual

HIGH-IMPEDANCE (HI-Z) FAULT DETECTION
• Load Event Detector algorithm
• Load Analysis algorithm
• Load Extraction algorithm
• Arc Burst Pattern Analysis algorithm
• Spectral Analysis algorithm
• Arcing-Suspected Identifier algorithm
• Even Harmonic Restraint algorithm
• Voltage Supervision algorithm
The following sections explain the algorithms.

9.1.2 Energy algorithm

The Energy algorithm monitors a specific set of non-fundamental frequency component energies of phase and neutral
current. After establishing an average value for a given component energy, the algorithm indicates arcing if it detects a
sudden, sustained increase in the value of that component. The Hi-Z element runs the Energy algorithm on each of the
following parameters for each phase current and for the neutral:
• Even harmonics
• Odd harmonics
• Non-harmonics
On a 60 Hz system, the non-harmonic component consists of a sum of the 30, 90, 150,..., 750 Hz components, while on a 50
Hz system, it consists of a sum of the 25, 75, 125,..., 625 Hz components. If the Energy algorithm detects a sudden,
sustained increase in one of these component energies, it reports this to the Expert Arc Detector algorithm, resets itself,
and continues to monitor for another sudden increase.

9.1.3 Randomness algorithm

The Randomness algorithm monitors the same set of component energies as the Energy algorithm but differs slightly.
Rather than checking for a sudden, sustained increase in the value of the monitored component energy, it looks for a
sudden increase in a component followed by highly erratic behavior. This type of highly erratic behavior is indicative of
many arcing faults. Just as with the Energy algorithm, if the Randomness algorithm detects a suspicious event in one of its
monitored components, it reports it to the Expert Arc Detector algorithm, resets itself, and continues to monitor for another
suspicious event.

9.1.4 Expert Arc Detector algorithm

The Expert Arc Detector algorithm assimilates the outputs of the basic arc detection algorithms into one "arcing
confidence" level per phase. Note that there are actually 24 independent basic arc detection algorithms, since both the
Energy algorithm and the Randomness algorithm are run for the even harmonics, odd harmonics, and non-harmonics for
each phase current and for the neutral. The assimilation performed by the Expert Arc Detector algorithm, then, is
accomplished by counting the number of arcing indications determined by any one of the 24 algorithms over a short
period of time (for example the last 30 seconds). Also taken into account is the number of different basic algorithms that
indicate arcing.
In the Expert Arc Detector algorithm, the arcing confidence level for each phase increases as the number of basic
algorithms that indicate arcing (per phase) increases. It also increases with increasing numbers of indications from any
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one basic algorithm. These increases in confidence levels occur because multiple, consecutive indications from a given
algorithm and indications from multiple independent algorithms are more indicative of the presence of arcing than a
single algorithm giving a single indication.
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CHAPTER 9: THEORY OF OPERATION
F60 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL