4.61
Date Code 20170814
Instruction Manual
SEL-700G Relay
Protection and Logic Functions
Group Settings (SET Command)
Figure 4.33
Loss-of-Field Element Operating Characteristic,
Positive Zone 2 Offset
Current Unbalance Elements
Generator unbalance current causes high rotor heating. IEEE Standard
C50.13-1977 defined the ability of generators to withstand unbalance current
in terms of negative-sequence current. The standard defines a continuous
withstand capability as well as a short-time capability, expressed in terms of
.
The SEL-700G provides a negative-sequence definite time-overcurrent
element suitable for unbalance alarm application and an
time-overcurrent
element for unbalance current tripping. The negative-sequence overcurrent
elements are supervised by the 46QTC torque-control setting.
Set E46 := Y to enable negative-sequence overcurrent elements. If negative-
sequence overcurrent protection is not necessary, set E46 := N. The Level 1
element is typically applied as an unbalance alarm. The pickup is defined in
percent of machine nominal phase current, INOM. Use the 46Q1D setting to
add any necessary delay. Disable the element by setting 46Q1P := OFF.
The 46Q1 Relay Word bit asserts without time delay when the measured
negative-sequence current exceeds 46Q1P percent of INOM. The 46Q1T
Relay Word bit asserts 46Q1D seconds after 46Q1 asserts if the unbalance
condition continues.
d
Table 4.11
Current Unbalance Settings
Setting Prompt
Setting Range
Setting Name :=
Factory Default
NEG-SEQ OC ENBL
Y, N
E46 := Y
LVL1 NEG-SEQ O/C
OFF, 2.0–100.0 %
46Q1P := 8.0
LVL1 TIME DELAY
0.02–999.90 s
46Q1D := 30
LVL2 NEG-SEQ O/C
OFF, 2.0–100.0 %
46Q2P := 8.0
LVL1 TIME DIAL
1–100
46Q2K := 10
46Q TRQCTRL
SEL
OGIC
46QTC := 1
I
2
2
t
I
2
2
t
Содержание SEL-700G Series
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