GE G60 Instruction Manual page 229

5 SETTINGS
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:
slope
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:
GE Multilin
830728A1.CDR
Figure 5–73: SPLIT PHASE PROTECTION FOR 2 CTS
830727A1.CDR
Figure 5–74: SPLIT PHASE PROTECTION FOR 1 CT
: load current, pickup: pickup setting, min_load: minimum load supervision setting
load
×
I slope I
=
bias load
I
Load CT Primary
split
---------- - × ---------------------------------------------------- -
=
I Load CT Secondary
load
( I I > pickup ) and
–
split bias
( > )
I I pickup and
–
split bias
G60 Generator Management Relay
Split Phase Load
Source Source
Split Phase Load
Source Source
offset
+
Split Phase CT Secondary
× --------------------------------------------------------------------- -
Split Phase CT Primary
( I ≥ min_load )
load
( ≥ )
I min_load
load
5.5 GROUPED ELEMENTS
(EQ 5.24)
(EQ 5.25)
(EQ 5.26)
(EQ 5.27)
5-131
5