GE G30 Instruction Manual page 301

5 SETTINGS
• SPLIT PHASE A(C) OFFSET: This setting specifies the steady-state split phase current at no-load for the each phase.
This should be set equal to the split phase current during normal (unfaulted) operation. The user should assign the split
phase current and the load current (positive sequence) to the data logger to identify the optimum value for this setting.
• SPLIT PHASE A(C) SLOPE: This setting specifies the slope of split phase characteristic for each phase. This setting
is used to bias the pickup of the element due to variations in generator loading. The slope is defined as the ratio of the
per-unit split phase current over the per-unit load current. The user should assign the split phase current and the load
current (positive sequence) to the data logger to identify the optimum value for this setting.
• SPLIT PHASE MIN LOAD: This setting specifies the minimum load (positive-sequence current) supervision level.
• SPLIT PHASE MODE: This setting specifies the mode of operation. If the "Over" mode is chosen, the element will
pickup when the split phase current is rises above the biased offset current plus the pickup setting. If "Over-under"
mode is chosen, the element will also pickup if the split phase current is falls below the biased offset current minus the
pickup setting. See the earlier description for further details.
• SPLIT PHASE DELAY: This setting specifies a time delay required to operate after the pickup condition is established.
During an external disturbance the CTs may saturate. CT saturation can cause a spurious split phase current, espe-
cially in the case where the split phase current is derived from the external summation of two split phase CTs (first fig-
ure above). In this instance, a time delay can be used to ride through the saturation event. Alternately, the CT
saturation flag can also be used to supervise the function.
GE Multilin G30 Generator Protection System
5.6 GROUPED ELEMENTS
5-171
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