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level of the voltage condition. Figure 2.15-2 shows the invers time characteristic of the OV
element when a multiplier setting [OV1-TMS] is used. The OV element uses Equation (2.15-1)
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 2.15-2 IDMT characteristic of OV element
Reset feature
The user should set the time for resetting. Figure 2.15-3 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 OV1 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)
- 168 -
��
]
( �� ��
⁄ ) − ��
��
TMS = 10
TMS = 5
TMS = 2
TMS = 1
2
2.5
3
6F2T0207 (0.01)
(2.15-1)
GRE200 (5,6)
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