GE Multilin DFF, Инструкция по эксплуатации, Страница: 14 / 74

OPERATING PRINCIPLES
GEK-106166E DFF Digital Feeder Relay 13
FREQ Type
The DFF unit stores up to 4 oscillography records, with a resolution of 2 samples per cycle. Each record has a
maximum capacity of 1584 cycles, and the number of pre-fault cycles is selectable between 2 and 80. Each record
includes the following information:
•
Frequency trend computed every semi-cycle.
•
Digital channels indicating status of protection functions.
•
Date and time.
•
Trigger source.
•
Active settings.
To start an oscillography record, the user can set up to 24 signals that will act as a trigger. For details see Chapter 2
- LIST OF SETTINGS .
The waveforms are stored in a file in COMTRADE format (IEEE C37.111-1991 Standard).The oscillography record
must be retrieved from the DFF relay by using GE-LOCAL or DFFPC communications software. They can be viewed
through GE-OSC software or any program that can read COMTRADE files. They can also be imported from
Microsoft EXCEL.
2.4 SETTING TABLES
The DFF provides three independent setting tables, TABLE 1, TABLE 2, TABLE 3, stored in non-volatile EEPROM
memory. Only one table is active at one time.
There are some settings that are common for the three setting tables: GENERAL SETTINGS, ACTIVE TABLE,
OSCILLOGRAPHY MASK and FUNCTION PERMIT . The rest of settings are independent for each table.
There is a setting called ACTIVE TABLE that defines which table is being applied.
There is another way of changing the active table. By using up to two digital inputs, called “ TABLE 0 SELECTION ”
and “ TABLE 1 SELECTION ” up to four different (0 to 3) combinations are possible.
The selected combination is obtained from the following table:
Number TABLE 1 SELECTION TABLE 0 SELECTION TABLE APPLIED
0 0 0
ACTIVE TABLE setting
1 0 1 1
2 1 0 2
3 1 1 3
NOTE: If any of the two digital inputs is active the “ACTIVE TABLE” setting is ignored