Iskra FPC 200 - Remanent Undervoltage Protection - ANSI Code 27 R

Functionality
40 USER MANUAL FPC 200 - 3/2017
Remanent undervoltage protection - ANSI code 27R
Remanent undervoltage protection is a function that prevents closing of the breaking element when voltage remaining by
rotating machines is still present on the load power line.
2.3.5.1 Functionality
Remanent undervoltage protection is a single phased
function, used as time delayed protection. It picks up
when ph-ph voltage U
L12
drops below the selected
threshold. The function can be enabled or disabled
through corresponding menu.
The selection of pickup value, pickup delay as well as
drop-out ratio and drop-out delay helps the user to fine
tune the protection according to the project
specifications.
27R Remanent UV
COUNTERS
0
Enabled:
1A 1B
No
Pickup:
Pickup value: 0,75xUn
Trip delay: 0,2s
0
Trip:
CONTROL SETTINGS
Pickup delay:
5ms
Drop-out delay:
0,2s
0,95 Drop-out ratio:
BLOCK SETTINGS
Input: none
Figure 2.29: Positive sequence undervoltage protection setting
as seen on HMI.
2.3.5.2 Delays
Function includes following delays explained in Chapter
2.1:
 Pickup delay
 Trip delay
 Drop-out delay
2.3.5.3 Block settings
Pickup of any instance separately of protection can be
individually blocked by:
 Any user defined signal [2.6.5].
 Enabling Fuse failure protection [2.6.4].
Protection is blocked when voltage drops below 5 % of
U
n
. To ensure the correct function of the protection, the
protection block is time delayed for a brief moment
after any condition for blocking has expired. The
individual protection trip exhibits pulse type if
connected to trip relay [4.2.4.5.7, relay mapping
section], to ensure correct CBFP [2.6.1.10] functionality.