Toshiba GRL150-100 Series Instruction Manual page 22

In addition to the above nine curve types, the OC1 can provide a user configurable IDMT curve. If
required, set the scheme switch [M∗∗∗] to "CON" and set the curve defining constants k, a, c, kr
and b. The following table shows the setting ranges of the curve defining constants.
Curve defining constants
k
a
c
kr
b
IEC/UK Inverse Curves
(Time Multiplier = 1)
1000
100
10
1
0.1
1
Current (Multiple of Setting)
Programmable Reset Characteristics
OC1 has a programmable reset feature: instantaneous, definite time delayed, or dependent time
delayed reset. (Refer to Appendix A for a more detailed description.)
Instantaneous resetting is normally applied in multi-shot auto-reclosing schemes, to ensure correct
grading between relays at various points in the scheme.
The dependent time delayed reset characteristic is particularly useful for providing correct
coordination with an upstream induction disc type overcurrent relay.
Table 2.3.1.2 Setting Range of IDMT Curves
Range
0.00 – 300.00
0.00 – 5.00
0.000 – 5.000
0.00 – 300.00
0.00 – 5.00
LTI
NI
VI
EI
10 100
Figure 2.3.1.1 IDMT Characteristics
⎯ 21 ⎯
Step Remarks
0.01 Operating characteristic
0.01 ([M∗∗∗]=CON setting)
0.001
0.01 Resetting characteristic
0.01 ([M∗∗∗]=CON, and [∗∗∗R]=DEP setting)
IEEE/US Inverse Curves
(Time Multiplier = 1)
100
10
1
0.1
1 10
Current (Multiple of Setting)
6 F 2 S 0 8 2 8
MI
VI
CO2
CO8
EI
100