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Time characteristic
The user should set DT for the scheme switches [OC1-Timer]. The value of the required
operate time is set for the setting [TOC1] in the range 0.00–300.00s.
Instantaneous activation
The operate time of the instantaneous characteristic is achieved by setting zero for the
[TOC1], but the instantaneous one can also obtained when the logic signal '1(High)' is
programmed to be injected at PLC connection point "OC1_INST_OP".
Reset time of IDMT
(vi)
Programming the reset time characteristic is available in the IEEE, US standards. It is also
allowed in original (user-programmable) inverse-time-reset characteristic. To get this
characteristic, the user should set DEP for setting [OC1-Rtimer]†. The following equation
defines the reset time for the inverse-time-reset characteristic. (ref. IEC 60255-151):
where,
t = time required for the element to reset fully after complete operation (seconds),
I = energizing current (amperes),
I s = threshold setting (amperes),
RTMS = time multiplier setting for resetting,
kr = time required to reset fully after complete operation when the energizing current is
zero (seconds),
β = constants defining curve.
For the IEEE standard, the user should use the setting [OC1-RTMS-IEEE] (incidentally,
the default value is 1.000). For the US standard and the original, settings [OC1-RTMS-US] and
[OC1-RTMS-ORG] are provided, respectively (For more information w.r.t the value for kr and
β, see Table 2.1-3; Figure 2.1-6 shows the characteristic curves).
†Note: To select the inverse-time-reset characteristic, set [OC1-Rtimer]=DEP.
Conversely set [OC1-Rtimer]=DEF to select definite-time-reset characteristic.
Note: For the setting [OC1-Rtimer]=DEP (inverse-time-reset), the integrated value will
be reduced in accordance to the magnitude of an energized current, when the
energized current is smaller than the setting [OC1]. The reducing degree will be
determined with the reset curve characteristics defined in the standards.
kr
t ( I ) = RTMS × [
1 − ( �� ��
⁄ )
- 24 -
]
β
��
6F2T0207 (0.01)
(2.1-2)
GRE200 (5,6)
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