Hitachi Relion 670 Series Applications Manual page 120

Section 8
Current protection
Trip time
tx
txMin
ANSI10000058 V1 EN-US
Figure 54:
In order to fully comply with the definition of the curve, the setting parameter txMin shall be set to a value
equal to the operating time of the selected inverse curve for twenty times the set current pickup value.
Note that the operate time is dependent on the selected time multiplier setting kx.
ResetTypeCrvx: The reset of the delay timer can be made as shown in Table 15.
Table 15:
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.
114
Minimum pickup current and trip time for inverse time characteristics
Reset possibilities
Curve index no.
1
2
3
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Pickup current
ANSI10000058-1-en.vsdx
Phasor measurement unit RES670
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Application manual