Toshiba GR-200 Series Instruction Manual page 115

Figure 2.5-3 IDMT Characteristics curves
Operate time of DT
(iv)
The operate time in the DT is a constant.
Time characteristic
The user should set DT for the scheme switch [OCN1-Timer]. The value of the required operate
time is set for the setting [TOCN1] in the range 0.00–300.00s.
Instantaneous activation
The instantaneous operation characteristic is achieved by setting zero for the [TOCN1], but the
instantaneous one can be also obtained when the logic signal "1 (High)" is programmed to be
injected at PLC connection point "OCN1_INST_OP".
Reset time of IDMT
(v)
Programming the reset time characteristic is available for the IEEE standard, US standard
and original (user-programmable) dependent time characteristic†. In the IEEE standard, for
example, the user can set DEP for the scheme switch [OCN1-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),
Is = threshold setting (amperes),
kr = time required to reset fully after complete operation when the energizing current is
zero
RTMS = time multiplier setting for resetting.
β = constants defining curve.
For setting RTMS for the IEEE standard, the user can use setting [OCN1-RTMS-IEEE]
(incidentally, the default value is 1.000). Similarly, settings [OCN1-RTMS-US] and [OCN1-
RTMS-ORG] are provided for the US standard and the original, respectively (For more
information w.r.t the values for kr and β, see Table 2.5-2; Figure 2.5-4 shows the characteristic
curves).
kr
�� ( I ) = �������� × [
1 − ( I I
⁄ )
- 96 -
]
β
s
6F2T0200 (0.15)
(2.5-5)
GRE200 (1,2)