Toshiba GR-200 Series Instruction Manual page 208

Operation feature
The operate time of the inverse (dependent) time characteristic is inversely proportional to the
level of the voltage condition. Figure 2.17-2 shows the invers time characteristic of the OVG
element when a multiplier setting is used. The OVG element uses Equation (2.17-1) to be in
conformity to IEC 60255-127:
where,
t = operating time (seconds),
V = energizing voltage (voltage),
Vs = pickup voltage setting (voltage), and
TMS = time multiplier setting to adjust a curve
Figure 2.17-2 IDMT characteristic of OVG element
Reset feature
The user should set the time for resetting. Figure 2.17-3 shows that examples of the pick-up
and the drop-off relevant to both the fault occurrences and the operation time. The value of the
time counter furnished in the OVG1 element is incremented if faults occur.
�� ( �� ) = ������ × [
Overvoltage Inverse Time Curves
1000.000
100.000
10.000
1.000
0.100
1 1.5
Applied Voltage (x Vs)
- 189 -
��
]
( �� ��
⁄ ) − ��
��
TMS = 10
TMS = 5
TMS = 2
TMS = 1
2 2.5 3
6F2T0200 (0.15)
(2.17-1)
GRE200 (1,2)