Toshiba GR-200 Series Instruction Manual page 66

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 [EF1-RTMS-IEEE]
(incidentally, the default value is 1.000). Similarly, settings [EF1-RTMS-US] and [EF1-RTMS-
ORG] are provided for the US standard and the original, respectively (For more information
w.r.t the values for the kr and β, see Table 2.2-2; Figure 2.2-4 shows the characteristic curves).
Table 2.2-2 Constants for inverse-time-reset characteristics
Curve Type
IEC 60255-151
A IEC Normal Inverse (IEC-NI‡)
B IEC Very Inverse (IEC-VI‡)
C IEC Extremely Inverse (IEC-EI‡)
- UK Long Time Inverse (UK-LTI‡)
D IEEE Moderately Inverse (IEEE-MI)
E IEEE Very Inverse (IEEE-VI)
F IEEE Extremely Inverse (IEEE-EI)
- US CO8 inverse (US-CO8)
- US CO2 short time inverse (US-CO2)
†Note: To select the inverse-time-reset characteristic, set [EF1-Rtimer]=DEP. Conversely
set [EF1-Rtimer]=DEF to select definite-time-reset characteristic.
Note: For the setting [EF1-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 [EF1]. The reducing degree will be
determined with the reset curve characteristics defined in the standards.
Note: For the setting [EF1-Rtimer]=DEF (definite-time-reset), the integrated value shall
be zero when an energized current is smaller than the setting [EF1], when the
small energized current is continued for timer setting [TEF1R]. The integrated
value will not be zero when the energized current does not flow small for the
setting [TEF1R]. DEF is allowed to set in the IEEE, US, and ORG. DEF is set
unconditionally in the IEC and UK.
kr
�� ( I ) = �������� × [
1 − ( I I
⁄ )
Curve Description
- 47 -
]
β
s
kr
sec
N/A
N/A
N/A
N/A
4.85
21.6
29.1
5.95
2.261
6F2T0200 (0.15)
(2.2-2)
β
N/A
N/A
N/A
N/A
2
2
2
2
2
GRE200 (1,2)