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 5 - 100% in steps of 1%.
The default setting is 20% and can be used if a deeper investigation shows that no other
value is needed..
HarmRestrainx: This parameter can be set Off/On, 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.
The operating current setting of the inverse time protection, or the lowest current step
of the definite time protection, must be defined 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
48.
Operate current
Current I
The IED does not reset
Line phase current
Time t
Reset current
IEC05000203-en-2.vsd
IEC05000203 V3 EN
Figure 48: Operate and reset current for an overcurrent protection
The lowest setting value can be written according to equation 15.
1MRK 505 291-UEN A Section 6
Current protection
99
Application manual
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