ABB RELION RET670, Applications Manual

Page: 805 / 1016

Q> : When the reactive power exceeds the value given by this setting, the output
QGTFWD will be activated after the time delay tPower . It shall be noticed that the
setting is given with sign, which effectively means that the function picks up for all
values of reactive power greater than the set value, similar to the functionality for
P> .
Q< : When the reactive power falls below the value given by this setting, the output
QLTREV will be activated after the time delay tPower . It shall be noticed that the
setting is given with sign, which effectively means that the function picks up for all
values of reactive power less than the set value, similar to the functionality for
P< .
tPower : Time delay for activation of the power monitoring output signals (PGTFWD,
PLTREV, QGTFWD and QLTREV).
Parallel control (ParCtrl)
OperationPAR : Setting of the method for parallel operation.
OperCCBlock : This setting enables/disables blocking if the circulating current exceeds
CircCurrLimit .
CircCurrLimit : Pick up value for the circulating current blocking function. The setting
is made in percent of I2Base .
tCircCurr : Time delay for the circulating current blocking function.
Comp : When parallel operation with the circulating current method is used, this setting
increases or decreases the influence of the circulating current on the regulation.
If the transformers are connected to the same bus on the HV- as well as the LV-side,
Comp can be calculated with the following formula which is valid for any number of
two-winding transformers in parallel, irrespective if the transformers are of different
size and short circuit impedance.
2 V
Comp a 100%
n p
´ D
= ´ ´
´
EQUATION1984-ANSI V1 EN-US
(Equation 515)
where:
•
D
V is the deadband setting in percent.
• n denotes the desired number of difference in tap position between the
transformers, that shall give a voltage deviation V
di
which corresponds to the
dead-band setting.
• p is the tap step (in percent of transformer nominal voltage).
1MRK 504 163-UUS A
Section 15
Control
Transformer protection RET670 2.2 ANSI 799
Application manual