Iskra FPC 200 - Phase to Phase Undervoltage Protection - ANSI Code 27

Functionality
36 USER MANUAL FPC 200 - 3/2017
Phase to phase undervoltage protection - ANSI code 27
Phase to phase undervoltage is a function that protects the feeder or other elements of the power system from low
voltage.
2.3.3.1 Functionality
Undervoltage protection is used as time delayed
protection. It picks up when ph-ph voltage drops below
the selected threshold. The function can be enabled or
disabled through corresponding menu.
Several ph-ph undervoltage protection instances with
different settings can run independently at the same
time.
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.
27 Undervoltage
COUNTERS
0
Enabled:
1A 1B 2A 2B 3A 3B
No
Pickup:
Pickup value: 0,75
Trip delay:
1,5s
0
Trip:
CONTROL SETTINGS
Pickup delay:
5ms
Drop-out delay:
0,2s
0,95 Drop-out ratio:
BLOCK SETTINGS
Input: none
Fuse failure: Yes
A
Figure 2.27: Ph-Ph undervoltage protection setting as seen on
HMI.
2.3.3.2 Delays
Function includes following delays explained in Chapter
2.1:
 Pickup delay
 Trip delay
 Drop-out delay
2.3.3.3 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].
In addition the protection is blocked when voltage drops
below 40 % 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.