ABB Relion 670 Series Applications Manual page 195

1MRK 511 407-UUS Rev. J
In order to achieve such protection functionality with one CVGAPC functions the following must be
done:
1. Connect three-phase generator currents to one CVGAPC instance (for example, GF01)
2. Set parameter
3. Set base current value to the rated generator current in primary amperes
4. Enable one overcurrent step (for example OC1)
5. Select parameter
=
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/
When the equation
OC1 step in it is obvious that if the following rules are followed:
1. set TD equal to the IEC or ANSI standard generator capability value
2. set parameter
3. set parameter
4. set parameters
5. set
then the OC1 step of the CVGAPC function can be used for generator negative sequence inverse
overcurrent protection.
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 the IEC standard or TD = 41.4 for the ANSI standard
4. set
5. set
6. set
7. set
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 the similar way rotor overload protection in accordance with ANSI standard can be achieved.
Phasor measurement unit RES670
Application manual
CurrentInput to value PosSeq
CurveType_OC1 to value Programmable
æ A ö
+
×
B
ç ÷
-
P
M C
è 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
IDMT calculation
93 is compared with the equation
A_OC1 equal to the value 1/x2
C_OC1 equal to the value 1/x2
B_OC1 = 0.0 and P_OC1 =2.0
PickupCurr_OC1 equal to the value x
A_OC1 = 1/1.162 = 0.7432
C_OC1 = 1/1.162 = 0.7432
B_OC1 = 0.0 and P_OC1 = 2.0
PickupCurr_OC1 = 116%
© Copyright 2017 Hitachi Power Grids. All rights reserved
94 for the inverse time characteristic of the
Section 11
Multipurpose protection
(Equation 94)
189