Remanent Undervoltage Protection - Ansi Code 27R - Iskra FPC 200 User Manual

Functionality

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 drops below the selected
L12
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
1A 1B
Enabled:
Pickup value: 0,75xUn
Trip delay:
CONTROL SETTINGS
Pickup delay:
Drop-out delay:
Drop-out ratio:
BLOCK SETTINGS
Input:
COUNTERS
Pickup:
Trip:
Figure 2.29: Positive sequence undervoltage protection setting
as seen on HMI.
40
No
0,2s
5ms
0,2s
0,95
none
0
0
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 . To ensure the correct function of the protection, the
n
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.
USER MANUAL FPC 200 - 3/2017