ABB Relion 670 Series Applications Manual page 167

1MRK 505 370-UUS Rev. K
Table 29:
Curve name
Instantaneous
IEC Reset (constant time)
ANSI Reset (inverse time)
The delay characteristics are described in the "Technical reference manual". There are some restrictions
regarding the choice of reset delay.
For the independent time delay characteristics the possible delay time settings are instantaneous (1) and
IEC (2 = set constant time reset).
For ANSI inverse time delay characteristics all three types of reset time characteristics are available;
instantaneous (1), IEC (2 = set constant time reset) and ANSI (3 = current dependent reset time).
For IEC inverse time delay characteristics the possible delay time settings are instantaneous (1) and IEC
(2 = set constant time reset).
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 then settings pr, tr and cr must be given.
HarmRestrainx: Enable freezing of timers step x 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 Off/On.
tPCrvx, tACrvx, tBCrvx, tCCrvx: Parameters for customer creation of inverse time characteristic curve
(Curve type = 17). See equation
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=
t s
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EQUATION1261 V2 EN-US
For more information, please refer to the "Technical reference manual".
tPRCrvx, tTRCrvx, tCRCrvx: Parameters for customer creation of inverse reset time characteristic curve
(Reset Curve type = 3). Further description can be found in the "Technical reference manual".
7.2.4.2 Second 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
component. This component can be used to create a restrain signal to prevent this unwanted function.
The settings for the 2
Busbar protection REB670
Application manual
Reset possibilities
Curve index no.
1
2
3
33
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÷
A
÷
+ ×
B IxMult
÷
p
æ ö
i
ç ÷ - ÷
C
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in
>
nd
harmonic restrain are described below.
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for the time characteristic equation.
Section 7
Current protection
(Equation 33)
SEMOD127941-90 v1
nd
harmonic
161