Siemens ISGS SG8158-00 - Manual (Page 30)

Protective Function Configuration
24 Siemens Energy & Automation, Inc.
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 (1803) depends on the sec-
ondary phase CT rating (1 A or 5 A) and the value is in sec-
ondary amperes.
The Time Dial parameter (1805) 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 (1806) 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.
The Reset parameter (1709) offers instantaneous or disk
emulation settings. Selecting Instantaneous causes the relay
to clear the timer when the current drops below the pickup
threshold. Selecting Disk Emulation causes the relay to simu-
late the integrating disk characteristics of electromechanical
relays, where the delay time decays over time. With disk
emulation, a relay that continuously picks up and drops out
will eventually trip. Set this parameter to Instantaneous when
using a custom curve.
Each of the two waveform capture buffers (1810 and 1811)
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.
5.8 Blocking Capability for Breaker or
Interrupter Saving
High-set instantaneous phase overcurrent (50HS) and high-
set instantaneous neutral or ground overcurrent (50HSN)
functions have the capability to block 50, 51, 50N, and 51N
selectively to prevent opening an interrupting device should
the fault current exceed the rating of the device.
This function is used to keep an electrically-operated load
break switch, recloser, or aging circuit breaker from attempt-
ing to interrupt current beyond its capability or rating. It must
be used in conjunction with a slight delay (25 ms) in 50 so
that 50HS can pickup or trip before 50 times out and trips.
Should these parameters be set, a fault large enough to
cause 50HS to pickup or trip before 50 has timed out will
prevent 50 and/or 51, 50N, and 51N from tripping.
50HS/N can also be matrixed to an output contact to block
differential tripping of a transformer differential relay when a
fault is between the interrupter and the high side (bushings)
of the transformer.
Figure 5.1 Blocking Capability Diagram
5.9 Directional Phase Time Overcurrent (67)
The Directional Phase Time Overcurrent function uses a
selected time overcurrent characteristic curve to determine
the trip time for the applied phase currents, utilizing the volt-
ages present on the VTs to determine current direction. The
defined characteristic curves are valid over a range of multi-
ple of pickup values. The function also includes a customer
defined curve. Refer to Appendix A for detailed trip curve
information. This function is only available if the voltage input
option is installed.
A1900 Directional Phase Time Overcurrent (67)
Address Parameter Option
1901 Function Enabled or Disabled
1902 Curve Inverse
Short Inverse
Long Inverse
Moderately Inverse
Custom
Very Inverse
Extremely Inverse
Slightly Inverse
Definite Inverse
I 2 T Without Limit
1903 Pickup 5 A CTs: 0.5-20 A or
1 A CTs: 0.1-4 A
(0.1 A steps)
1905 Time Dial 0.1-9.9 (0.1 steps)
1906 Filter rms or fundamental
1907 Impedance 0-90°
1908 Direction Forward or Reverse
1910 Freeze Wfm 1 on Pickup, on Trip, or None
1911 Freeze Wfm 2 on Pickup, on Trip, or None
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