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(v) Operate time of DT
The operate time in the DT is a constant.
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”.
(vi) Reset time of IDMT
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 2.15-4; Figure 2.15-6 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
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