Siemens SIPROTEC 7SJ61, Руководство пользователя, Страница: 197 / 454

Functions
2.13 Flexible Protection Functions
SIPROTEC, 7SJ61, Manual
C53000-G1140-C210-1, Release date 02.2008 197
Settings
The pickup thresholds, delay times and dropout ratios of the flexible protection function are set in the „Settings“
dialog box in DIGSI.
The pickup threshold of the function is configured via parameter
P.U. THRESHOLD
. The OFF-command delay
time is set via parameter
T TRIP DELAY
. Both setting values must be selected according to the required ap-
plication.
The pickup can be delayed via parameter
T PICKUP DELAY
. This parameter is usually set to zero (default
setting) in protection applications, because a protection function should pick up as quickly as possible. A setting
deviating from zero may be appropriate if a trip log is not desired to be started upon each short-term exceeding
of the pickup threshold, for example, with power protection or when a function is not used as a protection, but
as a monitoring function.
The dropout of pickup can be delayed via parameter
T DROPOUT DELAY
. This setting is also set to zero by
default (standard setting) A setting deviating from zero may be required if the device is utilized together with
electro-magnetic devices with considerably longer dropout ratios than the digital protection device (see Chapter
2.2 for more information). When utilizing the dropout time delay, it is recommended to set it to a shorter time
than the OFF-command delay time in order to avoid both times to "race".
The dropout ratio of the function can be selected in parameter
DROPOUT RATIO
. The standard dropout ratio
of protection functions is 0.95 (default setting). If the symmetrical current components are used, a dropout ratio
of at least 0.9 should be set. If the dropout ratio is decreased, it would be sensible to test the pickup of the
function regarding possible "chatter".
Renaming Messages, Checking Configurations
After parameterization of a flexible function, the following steps should be noted:
• Open matrix in DIGSI
• Rename the neutral message texts in accordance with the application.
• Check configurations on contacts and in operation and fault buffer, or set them according to the require-
ments.