ABB RELION RET670, Applications Manual

Page: 531 / 1016

Table 38: Reset possibilities
Curve name Curve index no.
Instantaneous 1
IEC Reset (constant time) 2
ANSI Reset (inverse time) 3
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 421 for the time characteristic
equation. For more information, refer to Technical manual .
[ ]
>
p
A
t s B MultPUx
i
C
in
= + ×
-
æ ö
ç ÷
ç ÷
ç ÷
æ ö
ç ÷ ç ÷
è ø è ø
ANSI-EQUATION1261 V1 EN-US
(Equation 421)
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 .
1MRK 504 163-UUS A
Section 9
Current protection
Transformer protection RET670 2.2 ANSI 525
Application manual