Toshiba GR200 Series Instruction Manual page 288

installed characteristic curves and one user-original characteristic carver where the user can
set the equation parameters. The inverse-time-reset curve equation and parameters will be
discussed in section (v).
Operate time of IDMT
(iii)
The dependent time in the IDMT is defined by Equation (2.17-4). (ref IEC 60255-151):
where:
t = operating time for constant current I (seconds),
I = energizing current (amperes),
Is = earth fault current setting (amperes),
TMS = time multiplier setting,
k, α, c = constants defining curve.
The nine pre-programmed standard characteristic curve are tabulated in Table 2.17-2;
additionally, one original (user-programmable) curve can be applied. One curve can be chosen
for each OCN stage by setting. Figure 2.17-3 illustrates these characteristic curves. For
example, the user should set one for the scheme switch [OCN1-Timer]: "IEC-NI" for IEC Normal
Inverse, "IEC-VI" for IEC Very Inverse, "IEC-EI" for IEC Extremely Inverse, "UK-LTI" for UK
Long Time Inverse, "IEEE-MI " for IEEE Moderately Inverse, "IEEE-VI" for IEEE Very Inverse,
"IEEE-EI" for IEEE Extremely Inverse, "US-CO2" for US CO2 short time inverse, "US-CO8" for
US CO8 inverse, and "Original" for user-programmable characteristic.
In the IDMT operation, the user can also program the characteristic using time-
multiplier-setting (TMS) for the required operate time. For example, when the IEC
characteristic is selected, the user can set the TMS value using the setting [OCN1-TMS-IEC]
(incidentally, the default value of the TMS is 1.00). The other TMSs are also available by the
[OCN1-TMS-UK], [OCN1-TMS-IEEE], [OCN1-TMS-US] and [OCN1-TMS-ORG].
Curve type
(IEC 60255-151)
A
B
C
-
D
E
F
-
-
�� ( �� ) = ������ × {[
( I I
Table 2.17-2 Constants for IDMT
Curve Description
IEC Normal Inverse (IEC-NI)
IEC Very Inverse (IEC-VI)
IEC Extremely Inverse (IEC-EI)
UK Long Time Inverse (UK-LTI)
IEEE Moderately Inverse (IEEE-MI)
IEEE Very Inverse (IEEE-VI)
IEEE Extremely Inverse (IEEE-EI)
US CO8 inverse (US-CO8)
US CO2 short time inverse (US-CO2)
- 265 -
k
] + c}
α
⁄ ) − 1
s
k
0.14
13.5
80
120
0.0515
19.61
28.2
5.95
0.02394
6F2S1914 (0.49)
(2.17-4)
α c
0.02 0
1 0
2 0
1 0
0.02 0.114
2 0.491
2 0.1217
2 0.18
0.02 0.01694
GRL200 (Soft 033 & 037)