1-20
ALPS Advanced Line Protection System
GE Power Management
1.6 COMMUNICATIONS
1 PRODUCT DESCRIPTION
1
1.6 COMMUNICATIONS
1.6.1 KEYPAD AND DISPLAY
A local user interface, incorporating a keypad and display, is provided to enter settings, display present values, view fault
target information, and access stored data (see Chapter 8 for details). Passwords provide security for keypad access.
Three separate passwords provide local keypad security against inadvertent breaker operations and settings changes. No
password is required to view data stored in the relay. The three levels of password protection are:
CONTROL: Allows control operations (trip and close the breakers).
SETTINGS: Allows settings changes.
MASTER: Allows both control operations and settings changes.
Refer to Section 8.1.21: CHANGE PASSWORD on page 8–14 for a description of the keypad password usage.
1.6.2 SERIAL COMMUNICATIONS
A DB-9 plug RS232 port (Port 1) on the front panel provides local serial communication via an IBM PC-compatible com-
puter. One or two rear ports (RS232 or RS485) are provided for serial communications. Port 2 is standard on all models.
When Port 2 is configured as RS232, connection is made using a DB25 plug; when Port 2 is configured as RS485, connec-
tion is made using a 4-pin Phoenix plug. Port 3 is optional (depending on the model) and uses a DB25 plug for either
RS232 or RS485. The communications protocol for each port may be selected independently as either GE-Modem, ASCII,
or DNP 3.0. Each port may be set independently for data communications from 300 to 9600 bps. In addition, Port 2 has the
ability to accept a plug in communication module that can support the Modbus RTU communications protocols.
Four different passwords provide remote serial communications security. The levels of password protection for communica-
tions are:
VIEW: Allows remote access to the ALPS to view and retrieve stored data.
CONTROL: Allows control operations (trip and close the breakers).
SETTINGS: Allows settings changes.
MASTER: Allows both control operations and settings changes.
Refer to Chapter 11: ALPS-LINK USER GUIDE for a description of ALPS-Link and Chapter 12: ASCII COMMUNICATIONS
for ASCII port password usage. The Modbus memory map and DNP 3.0 protocol information are contained in Appendices
B and C, respectively.
1.6.3 SCADA DIGITAL TO ANALOG (DTA) INTERFACE
An internal DTA function, standard on the ALPS, provides the following:
•
An analog output proportional to the distance from the relay to the fault as calculated by the fault-location algorithm.
•
Four contact outputs that provide fault-type information.
The analog output is intended to be wired into an analog port of a SCADA RTU to provide remote indication of distance to
the fault. The four contact outputs are designated phase A, phase B, phase C, and neutral and are intended to be wired into
four separate RTU digital ports. A particular contact closes when its phase (or neutral) is involved in the fault. For a phase
B-to-C-to-ground fault, the phase B, phase C, and neutral contacts close.
The DTA provides either a nominal 0 to 1 mA DC output or a nominal 0 to 5 V DC output. The choice of output ranges is
made by a switch located on the Processor Board. The Processor Board must be removed from the ALPS chassis to
access this switch. For the proper sequence, see Chapter 9: SERVICING.
When the fault location is calculated to be 100% of the line length, the DTA output is either 0.8 mA DC or 4.0 V DC. The
DTA output goes to full scale (either 1 mA DC or 5 V DC) when the fault location is calculated to be greater than 110% of
the line length. Consequently, the usable output ranges are 0 to 0.88 mA DC or 0 to 4.4 V DC, which covers the 0 to 110%
fault-location range. The SCADA system should be programmed to recognize a full-scale output as an indication of an
invalid output, resulting from either an out-of-limit fault-location calculation or a DTA reset.
Two settings are associated with the SCADA DTA Interface. FLTLOCK specifies a time after a fault during which fault-loca-
tion calculations resulting from subsequent faults are prevented from updating the fault-location information stored in the
DTA logic. FLTRESET specifies the time after a fault at which the fault-location information stored in the DTA logic is reset
(output forced to full-scale value) and those fault-type contacts that have closed will open. When either the ALPS date or
time is changed the timers associated with FLTLOCK and FLTRESET are reset and the DTA logic is reset. Fault phase
identification dry contacts for A, B, C, and N phases must be programmed by the user. Refer to Chapter 3 for details.
