Over Frequency Threshold
This is the frequency (in hertz) above which a
Trip
operation will occur. Enter between
50 and 62 Hz, but the setting will be valid only if it falls within the range (System Frequency,
System Fre 2). (Minimum: System Frequency; Maximum: System Frequency
+ 2 Hz; Default: System Fre 0.5 Hz; Increment: 0.02)
Frequency Time to Trip
This is the time (in seconds) the underfrequency or overfrequency threshold must be
exceeded for a
Trip
operation to occur. (Range: 0.06-600.00; Step: 0.02; Default: 30.00)
Reset Time
This is the time (in seconds) good frequency must be present for the
Frequency
element
to reset. (Range: 0.06-600.00; Step: 0.02; Default: 1.00)
Low Frequency Indication
(IntelliTeam SG System and Loop Restoration Only)
The
Low-Frequency Indication
mode detects an underfrequency event immediately
before loss of voltage so the loop-restoration system or the IntelliTeam SG Automatic
Restoration System can be taken out of the
Ready
state to prevent automatic load pick
up during an underfrequency load-shedding event.
This feature should be coordinated with the underfrequency-detection scheme that
will result in the load-shedding operation. The
Under Minimum Time Detect
setpoint
must be faster than the underfrequency-detection scheme to ensure the low frequency
indication will prohibit restoration before an underfrequency load-shed event. Similarly,
if the IntelliRupter fault interrupter’s
Under Frequency Trip
element is used to open
the device with IntelliTeam SG restoration software, the
Under Minimum Time Detect
setpoint must be faster than the
Frequency Time to Trip
setpoint to ensure restora-
tion is prohibited before the
Trip
operation. The
Under Frequency Trip
element will
not disable the
Loop Restoration
mode or IntelliTeam SG system-restoration features
when it trips open the IntelliRupter fault interrupter.
Loop Restoration:
When the
Good Frequency to Close
setting for the profile
designated on the
Setup>Restoration>Loop
screen is set to the
Yes
state and the
Under
Frequency Enabled
setpoint is also set to the
Yes
state, a Loop Restoration
Close
command will be blocked if the frequency is below the active
Under Frequency
Threshold
setpoint for the configured
Under Frequency Minimum Time to Detect
setpoint. Loop restoration must be manually enabled after the low-frequency condition
has cleared. (The Under Frequency Threshold default value = System Frequency –
0.5 Hz, 49.50 Hz when
Setup>General>Site-Related>System Frequency
= 50 Hz or
59.50 Hz when
Setup>General>Site-Related>System Frequency
= 60 Hz; Minimum:
System Frequency – 3 Hz; Maximum: System Frequency; Increment: 0.01 Hz) Configure
the
Under Frequency Minimum Time to Detect
setpoint. (Range:0.10-10.0; Step: 0.02)
IntelliTeam SG System:
When the
Under Frequency Enabled
setpoint is set to
the
Yes
state and the
Under Frequency Threshold
setpoint identifies an underfre-
quency load-shed event (the underfrequency is at or below the active
Under Frequency
Threshold
setpoint for the duration of the
Under Frequency Minimum Time to
Detect
Timer
), it sets the IntelliTeam SG system to the
Prohibit Restoration
mode,
and the IntelliRupter fault interrupter goes out of the
Ready
state at that location. When
an IntelliRupter fault interrupter is not in the
Ready
state, restoration must be manually
enabled to return the IntelliTeam SG system to the
Normal
state.
84 S&C Instruction Sheet 766-530
Protection Setup
