GE G60 Instruction Manual page 370

5.6 GROUPED ELEMENTS
The split phase element allows a separate pickup setting to be applied for each phase. Additionally, the pickup can be
biased by the load current (slope characteristic). Two modes of operation are supported (over and over-under).
5
The split phase element principle of operation is as follows. First, define the following parameters:
I : split-phase current, I
split
Then, the expected value of the steady state unbalance (defined as bias current) is expressed as follows:
where:
and offset is the split phase current at no-load. In "Over" mode, the element will pickup if:
In "Over-under", mode, the element will pickup if:
5-210
830728A1.CDR
Figure 5–102: SPLIT PHASE PROTECTION FOR 2 CTS
830727A1.CDR
Figure 5–103: SPLIT PHASE PROTECTION FOR 1 CT
: load current, pickup: pickup setting, min_load: minimum load supervision setting
load
I slope I
=
bias
I
Load CT Primary
split
---------- - × ---------------------------------------------------- -
slope
=
I Load CT Secondary
load
( I I > pickup )
–
split bias
G60 Generator Protection System
Split Phase Load
Source Source
Split Phase Load
Source Source
×
offset
+
load
Split Phase CT Secondary
× --------------------------------------------------------------------- -
Split Phase CT Primary
and ( I ≥ min_load )
load
5 SETTINGS
(EQ 5.24)
(EQ 5.25)
(EQ 5.26)
GE Multilin