Siemens ISGS SG8158-00 - Manual (Page 31)

Protective Function Configuration
Siemens Energy & Automation, Inc. 25
The Directional Phase Time Overcurrent function can be
enabled or disabled (1901).
The Curve parameter (1902) allows the selection of the pre-
programmed characteristic curve used by this function. The
ISGS relay comes with nine standard overcurrent character-
istic curves that can be adjusted with the Time Dial parame-
ter. The custom curve is a user-definable protective curve
that integrates with instantaneous reset. The lower limit of
the custom curve is 1.10. The maximum time to trip is the
time at 1.10.
The range of the pickup value (1903) depends on the sec-
ondary phase CT rating (1 A or 5 A) and the value is in sec-
ondary amperes. The function begins timing when any
individual phase current exceeds the pickup current setting.
The Time Dial parameter (1905) used for the selected curve
allows the time-to-trip of the curve to be raised or lowered
The dial can be adjusted from 0.1 to 9.9 in steps of 0.1.
The Filter parameter (1906) sets the sensing method used by
the function in its pickup calculations. The rms filter uses fun-
damental current plus harmonics, while the fundamental filter
ignores harmonics.
Impedance (1907) sets the angle used by this function.
Impedance determines the direction of current flow being
measured and can be set from 0 to 90 degrees. The direc-
tional characteristic (line) in the complex impedance plane is
shown in Figure 5.2. The directional characteristic is always
perpendicular to the line impedance vector.
The sensing direction (1908) can be set to forward or
reverse. The forward setting allows the directional protection
element to pickup on fault current only in the direction oppo-
site to normal power flow.
Figure 5.2 Directional Characteristic
Each of the two waveform capture buffers (1910 and 1911)
can be independently programmed to freeze snapshots on
pickup or trip.
The function is able to actuate any binary output contact on
pickup, and any trip or binary output contact on trip.
5.10 Directional Neutral or Ground Time
Overcurrent (67N)
The Directional Neutral or Ground Time Overcurrent function
uses a selected time overcurrent characteristic curve to
determine the trip time for the applied current at the fourth
current input, utilizing the voltages present on the VTs to
determine current direction. The defined characteristic
curves are valid over a range of multiple of pickup values.
The function also includes a customer defined curve. Refer
to Appendix A for detailed trip curve information. This func-
tion is only available if the voltage input option is installed.
The Directional Neutral or Ground Time Overcurrent function
can be enabled or disabled (2001).
The Curve parameter (2002) allows the selection of the pre-
programmed characteristic curve used by this function. The
ISGS relay comes with nine standard overcurrent character-
istic curves that can be adjusted with the time dial parameter
(see below). The custom curve is a user-definable protective
curve that integrates with instantaneous reset. The lower limit
of the custom curve is 1.10. The maximum time to trip is the
time at 1.10.
A2000 Directional Neutral or Ground Time Overcurrent
(67N)
Address Parameter Option
2001 Function Enabled or Disabled
2002 Curve Inverse
Short Inverse
Long Inverse
Moderately Inverse
Custom
Very Inverse
Extremely Inverse
Definite Inverse
Slightly Inverse
I 2 T Without Limit
2003 Pickup 5 A CTs: 0.5-20 A or
1 A CTs: 0.1-4 A
(0.1 A steps)
2005 Time Dial 0.1-9.9 (0.1 steps)
2006 Filter rms or fundamental
2007 Impedance 0-90°
2008 Direction Forward or Reverse
2010 Freeze Wfm1 on Pickup, on Trip, or None
2011 Freeze Wfm2 on Pickup, on Trip, or None
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