3-58
Overcurrent, Voltage, Synchronism Check, Frequency, and Power Elements
Date Code 20001006
SEL-351 Instruction Manual
Voltage Sag, Swell, and Interruption Elements Settings
Settings are enabled with the ESSI (enable sag/swell/interruption elements) settings shown in Table
3.12.
Table 3.12: Sag/Swell/Interruption Elements Settings
Settings
Definition
Range
VINT
percentage of memory
voltage compared
against phase voltage to
assert INT elements
0 - 90 % of memorized positive-sequence
voltage
VSAG*
percentage of memory
voltage compared
against phase voltage to
assert SAG elements
10 - 90 % of memorized positive-sequence
voltage
VSWELL
percentage of memory
voltage compared
against phase voltage to
assert SW elements
110 - 180 % of memorized positive-sequence
voltage (300 V maximum upper limit for
300 V voltage inputs, 150 V for 150 V voltage
inputs)
* VSAG is set equal to VINT if an attempt is made to set VSAG less than VINT.
P
OWER
E
LEMENTS
(A
VAILABLE IN
F
IRMWARE
V
ERSIONS
2
AND
4)
Four independent power elements are available. The desired number of power elements is enabled
with the EPWR (enable power elements) setting:
EPWR = N (none), 1 through 4.
Each enabled power element operates on a per-phase basis. These per-phase power elements can
be set to detect real power or reactive power. With SEL
OGIC
Control Equations, the power
elements provide a wide variety of protection and control applications. Typical applications are:
•
Overpower and/or underpower protection/control
•
Reverse power protection/control
•
VAR control for capacitor banks
Summary of Contents for SEL-351
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