ABB Relion 650 Series Applications Manual page 81

1MRK 505 287-UUS B
Operate time
tx
tnMin
IEC09000164 V2 EN-US
Figure 29: Minimum operate current and operation time for inverse time characteristics
In order to fully comply with curves definition setting parameter
which is equal to the operating time of the selected inverse curve for measured current of twenty
times the set current pickup value. Note that the operating time value is dependent on the
selected setting value for time multiplier
HarmRestrainx : Enable block of step n from the harmonic restrain function (2nd harmonic). This
function should be used when there is a risk if power transformer inrush currents might cause
unwanted trip. Can be set
7.1.3.2 2nd harmonic restrain
If a power transformer is energized there is a risk that the transformer core will saturate during
part of the period, resulting in an inrush transformer current. This will give a declining residual
current in the network, as the inrush current is deviating between the phases. There is a risk that
the phase overcurrent function will give an unwanted trip. The inrush current has a relatively large
ratio of 2
prevent this unwanted function.
The settings for the 2nd harmonic restrain are described below.
2ndHarmStab : The rate of 2nd harmonic current content for activation of the 2nd harmonic
restrain signal, to block chosen steps. The setting is given in % of the fundamental frequency
residual current. The setting range is
be used if a deeper investigation shows that no other value is needed..
HarmRestrainx : This parameter can be set Disabled / Enabled , to disable or enable the 2nd
harmonic restrain.
The four step phase overcurrent protection 3-phase output can be used in different ways,
depending on the application where the protection is used. A general description is given below.
Busbar protection REB650
Application manual
IMinn
Disabled / Enabled .
nd
harmonic component. This component can be used to create a restrain signal to
© Copyright 2013 ABB. All rights reserved
Current
IEC09000164-2
TDn .
5 - 100 % in steps of 1%. The default setting is 20% and can
Current protection
tnMin shall be set to the value,
Section 7
M12982-91 v7
75