1-16
ALPS Advanced Line Protection System
GE Power Management
1.5 OTHER FEATURES
1 PRODUCT DESCRIPTION
1
1.5 OTHER FEATURES
1.5.1 FLASH MEMORY
The program code resides in Flash memory rather than EPROM. This new technology provides the same functionality dur-
ing normal operations of the relay. The advantage to the Flash Memory is it can be changed for software upgrades without
opening the relay. The contents can be overwritten through the communications ports already provided in the relay. The
ability to change the contents requires special software and does not come with any of the standard communications pack-
ages available for the ALPS.
1.5.2 LINE OVERLOAD
The Line Overload function provides an event and a programmable signal. This signal can be used to provide alarm indica-
tion (contact closure) that the load current on the protected line has exceeded a set level for a set time interval. Two alarm
levels are included. Level 1 is generally set with a lower pickup setting and a longer time delay than level 2.
1.5.3 CURRENT UNBALANCE DETECTION
If the Fault Detector remains picked up for 60 seconds, a non-critical alarm is issued and an event message generated.
This function indicates sustained unbalanced current conditions such as a shorted or open current transformer.
1.5.4 FAULT LOCATION
A separate algorithm provides fault-location information, which is presented as miles, kilometers, or percent of line from the
relay location to the fault. The distance to the fault is based on a line length provided by the user as a setting. Fault location
output is displayed on the front panel liquid crystal display as part of the target information following a relay trip, and it is
also contained in the Fault Report described below.
1.5.5 FAULT REPORT
When a fault or oscillography trigger occurs, pertinent information, consisting of unit ID, date and time, operating time, pre-
fault currents, fault currents and voltages, fault type, trip type, distance to fault, and selected events, is stored in memory.
The number of fault events that are stored is selectable by the user. A relay with standard memory option may be set for: 2,
4, 8, or 12 fault reports. A relay with extended memory option may be set for 6, 12, 24, or 36 fault reports. Each fault report
is associated with an oscillography data file. See Section 8.2.3: REQUEST FAULT INFORMATION on page 8–17 for
obtaining a fault report through the local user interface and Section 11.6: INFORMATION on page 11–14 for fault reports
using ALPS-Link.
1.5.6 OSCILLOGRAPHY
Oscillography data are stored in memory each time the ALPS issues a trip and, optionally when an internal oscillography
trigger flag is set or an external contact is closed. Protection Setting 2026: CONFOSC, allows a configurable oscillography
trigger to be assigned by Xpression Builder. Note that OSC Trigger stores oscillography data, but does not necessarily set
t = 0, the time sample that delineates between prefault and postfault oscillography cycles. The term
disturbance period is
defined as the number of cycles of oscillography data (prefault plus postfault) as determined by General Setting 301: NUM-
FAULTS. If the internal Fault Detector, FD, comes up initially and OSC Trigger follows within the disturbance period, oscil-
lography data are stored whether or not the ALPS issues a trip.
If the ALPS issues a trip, then a normal fault report is stored as part of the oscillography data. If the ALPS does not issue a
trip, a pseudofault report is created. The trip type is listed as OSC, the trip time is set to when the OSC Trigger occurred,
the operating time is set to zero, and the fault type and location are computed, based on post-OSC Trigger data. The local
LCD display does not show target information, but an event message and fault report are stored in memory. In either case
above, t = 0 is determined by the internal Fault Detector (FD).
If OSC Trigger comes up initially and FD follows within the disturbance period, the same actions occur and FD determines
t = 0. If only OSC Trigger occurs, then a pseudofault report is created and OSC Trigger determines t = 0. This arrangement
assures that the oscillography function always captures an ALPS trip, with FD determining t = 0, regardless of whether an
optional internal or external trigger is used.
