ABB Relion 670 Series Applications Manual page 168

Section 7
Current protection
2ndHarmStab: The rate of second harmonic current content for activation of the 2
signal, to block chosen steps. The setting is given in % of the fundamental frequency residual current.
The setting range is 5-100% in step of 1%. The default setting is 20%.
HarmRestrainx: This parameter can be set Off/On, disable or enable the 2
The four-step phase overcurrent protection can be used in different ways, depending on the application
where the protection is used. A general description is given below.
The pick up current setting inverse time protection or the lowest current step constant inverse time
protection must be given a current setting so that the highest possible load current does not cause
protection operation. Here consideration also has to be taken to the protection reset current, so that a
short peak of overcurrent does not cause operation of the protection even when the overcurrent has
ceased. This phenomenon is described in figure 92.
Current (A)
IEC05000203 V4 EN-US
Figure 92:
The lowest setting value can be written according to equation 34.
³
Ipu 1.2
EQUATION1262 V2 EN-US
where:
1.2
k
I
max
162
Operate current
Reset current
The IED does not reset
Pick up and reset current for an overcurrent protection
Im ax
×
k
is a safety factor,
is the resetting ratio of the protection, and
is the maximum load current.
© 2017 - 2021 Hitachi Power Grids. All rights reserved
1MRK 505 370-UUS Rev. K
nd
harmonic restrain
nd
harmonic restrain.
Line phase current
Time (s)
IEC05000203-en-2.vsd
Busbar protection REB670
(Equation 34)
Application manual