Toshiba GR200 Series Instruction Manual page 276

Operation feature
The operate time of the inverse (dependent) time characteristic is inversely proportional to the
level of the voltage condition. Figure 2.14-2 shows the invers time characteristic of the OVG
element when a multiplier setting is used. The OVG element uses Equation (2.14-1) 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
If the user will require a user-programmable (original) curve in the inverse time
characteristic, it is provided when the constants of k, a, c are set, as shown in Table 2.14-2. For
example, the user-programmable (original) curve in the OVG1 element will be acquired when
Original is set for the scheme switch [OVG1-Timer], and when values of respective constants
are set for [OVG1-k], [OVG1-a], and [OVG1-C].
Figure 2.14-2 IDMT characteristic of OVG element
t ( G ) = TMS × {[
( �� ��
Overvoltage Inverse Time Curves
1000.000
100.000
10.000
1.000
0.100
1 1.5
Applied Voltage (x Vs)
- 255 -
��
] + ��}
��
⁄ ) − 1
��
TMS = 10
TMS = 5
TMS = 2
TMS = 1
2 2.5 3
6F2S1915 (0.46)
(2.14-1)
GRZ200 (Soft 031 & 032)