2Nd Harmonic Restrain - ABB Relion 670 Series Applications Manual

1MRK 511 358-UUS A
For the customer tailor-made inverse time delay characteristics (type 17), all three types of reset
time characteristics are available: instantaneous (1), IEC (2 = set constant time reset) and ANSI (3 =
current dependent reset time). If the current-dependent type is used, settings
be given.
tResetx : Constant reset time delay in seconds for step x.
tPCrvx , tACrvx , tBCrvx , tCCrvx : These parameters are used by the customer to create the inverse
time characteristic curve. See equation
information, refer to
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ANSI-EQUATION1261 V1 EN-US
tPRCrvx , tTRCrvx , tCRCrvx : These parameters are used by the customer to create the inverse reset
time characteristic curve. For more information, refer to
HarmRestrainx : Enables the block of step x from the harmonic restrain function (2nd harmonic).
This function should be used when there is a risk of an unwanted trip caused by power
transformer inrush currents. It can be set to
7.2.3.2

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.
The pickup 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 57.
Application manual
Technical manual .
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harmonic component. This component can be used to create a restrain signal to
28 for the time characteristic equation. For more
Technical manual .
Disabled / Enabled .
5 - 100 % in steps of 1%. The default setting is 20% and can
Section 7
Current protection
pr , tr and cr must
(Equation 28)
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