ABB Relion 670 Series Applications Manual page 253
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- Technical manual (1432 pages) ,
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1MRK 505 370-UUS Rev. K
1.
Connect three-phase generator currents to one CVGAPC instance (for example, CVGAPC:2)
2.
Set parameter CurrentInput to value PosSeq
3.
Set base current value to the rated generator current in primary amperes
(the correct Global Base values group shall be selected by the parameter GlobalBaseSel)
4.
Enable one overcurrent step (for example OC1)
5.
Select parameter CurveType_OC1 to value Programmable
=
t
TD
op
EQUATION1745-ANSI V1 EN-US
where:
t
op
TD
M
A, B, C and P are user settable coefficients which determine the curve used for Inverse Time Overcurrent TOC/IDMT
When the equation
step, it is obvious that if the following rules are followed:
1.
set TD equal to the ANSI or IEEE standard generator capability value
2.
set parameter A_OC1 equal to the value (1/x)
3.
set parameter C_OC1 equal to the value (1/x)
4.
set parameters B_OC1 = 0.0 and P_OC1=2.0
5.
set PickupCurr_OC1 equal to the value x
then the OC1 step of the CVGAPC function can be used for generator stator overload protection in
accordance with ANSI or IEEE standard.
1.
select positive sequence current as measuring quantity for this CVGAPC function
2.
make sure that the base current value for CVGAPC function is equal to the generator rated current
3.
set TD = 37.5 for either the ANSI or IEEE standards
4.
set A_OC1= (1/1.15)
5.
set C_OC1= (1/1.15)
6.
set B_OC1 = 0.0 and P_OC1 = 2.0
7.
set PickupCurr_OC1 = 115%
Proper timing of CVGAPC function made in this way can easily be verified by secondary injection. All
other settings can be left at the default values. If required delayed time reset for OC1 step can be set in
order to insure proper function operation in case of repetitive overload conditions.
Furthermore the other built-in protection elements can be used for other protection and alarming
purposes.
In a similar way rotor overload protection in accordance with IEEE standard can be achieved.
Busbar protection REB670
Application manual
æ
ö
A
+
×
B
ç
÷
-
P
è
M
C
ø
is the operating time in seconds of the Inverse Time Overcurrent TOC/IDMT algorithm
is time multiplier (parameter setting)
is ratio between measured current magnitude and set pickup current level
calculation
85
is compared with the equation
2
= 0.7561
2
= 0.7561
© 2017 - 2021 Hitachi Power Grids. All rights reserved
86
for the inverse time characteristic of the OC1
2
2
Section 10
Multipurpose protection
(Equation 86)
247
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