Iskra FPC 200 - Phase Undercurrent Protection - ANSI Code 37

Functionality
28 USER MANUAL FPC 200 - 3/2017
Phase undercurrent protection - ANSI code 37
Phase to phase undercurrent is a function that protects the rotating machine or other elements of the power system from
low current.
2.2.5.1 Functionality
Undercurrent protection is used as time delayed
protection. It picks up when one of the phase currents
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.
37 Undercurrent
Enabled:
No
Pickup value: 0.7In
A
Trip delay: 0.4s
1A 1B
CONTROL SETTINGS
Pickup delay:
0.4s
A
Figure 2.23: Phase undercurrent protection setting as seen on
HMI.
2.2.5.2 Delays
Function includes following delays explained in Chapter
2.1:
 Pickup delay
 Trip delay
 Drop-out delay
2.2.5.3 Block settings
Pickup of any instance separately of protection can be
individually blocked by:
 Any user defined signal [2.6.5].
 Defined zero current level.
In addition 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.