ABB RELION RET670 Applications Manual page 531

1MRK 504 163-UUS A
Transformer protection RET670 2.2 ANSI
Application manual
Table 38: Reset possibilities
Curve name
Instantaneous
IEC Reset (constant time)
ANSI Reset (inverse time)
The delay characteristics are described in Technical manual. There are some
restrictions regarding the choice of the reset delay.
For the definite time delay characteristics, the possible delay time setting instantaneous
(1) and IEC (2 = set constant time reset).
For ANSI inverse time 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 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, settings pr, tr and cr must 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
equation. For more information, refer to Technical manual.
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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 Technical
manual.
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 Disabled/Enabled.
Curve index no.
1
2
3
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÷
÷
×
B MultPUx
÷
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Section 9
Current protection
421 for the time characteristic
(Equation 421)
525