Low Three-Phase Voltage Alert
This feature is based on the Trip on Three-Phase Voltage element but is not a protection
element and will not lead to any IntelliRupter fault interrupter action. Instead, it noties
the user via the Operation screen and a SCADA message that a low-voltage condition
exists on three phases. There is no SCADA-acknowledge functionality. The DNP point
will be active when voltage is below the alert setting for approximately one second. The
DNP point clears when voltage is above the threshold. To avoid ooding the logs and
creating a urry of SCADA alerts when the voltage hovers at the threshold level, the DNP
point is not allowed more than one transition (on or off) per minute. (Setting options:
Yes or No; default = No)
Low Three-Phase Low Voltage Threshold
This is the percentage of line-to-ground RMS phase voltage below which a Three-Phase
Voltage Alert state occurs. (Range: 5-100; Step: 1; Default: 75)
Figure 50. The Setup>Protection>General Profile 1>Voltage, Frequency, and Sectionalizing>
Frequency Trip screen.
Under Frequency Enabled
Specify the Yes or No (default) option.
Under Frequency Threshold
This is the frequency (in hertz) below which a Trip operation will occur. Enter between
47 and 60 Hz, but the setting is valid only if it falls within the range (System Frequency - 3,
System Frequency). (Minimum: System Frequency - 3 Hz; Maximum: System Frequency;
Default: System Frequency - 0.5 Hz; Increment: 0.02)
Over Frequency Enabled
Specify the Yes or No (default) option.
Frequency Trip Section
Each General Prole feature has settings for multiple Frequency Trip elements. See
Figure 50.
Frequency Trip
S&C Instruction Sheet 766-530 83
Protection Setup
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