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reset threshold, the integral state (the point towards operation that it has travelled) of the timing
function (IDMT) is held for that period.
This does not apply following a trip operation, in which case resetting is always instantaneous.
The OV1 has a programmable dropoff/pickup(DO/PU) ratio.
Scheme Logic
Figure 2.2.3 shows the scheme logic of the overvoltage protection with selective definite time or
inverse time characteristic.
The definite time protection is selected by setting [OV1EN] to "DT". Definite time element
OV1-D is enabled for overvoltage protection, and trip signal OV1 TRIP is given through the
delayed pick-up timer TOV1.
The inverse time protection is selected by setting [OV1EN] to "IDMT". Inverse time element
OV1-I is enabled for overvoltage protection, and trip signal OV1 TRIP is given.
These protections can be disabled by the scheme switch [OV1EN] or PLC logic signal OV1
BLOCK.
Overvoltage Inverse Time Curves
1000.000
100.000
10.000
1.000
0.100
1
1.5
2
Applied Voltage (x Vs)
Figure 2.2.2
IDMT Characteristic
⎯
⎯
75
TMS = 10
TMS = 5
TMS = 2
TMS = 1
2.5
3
6 F 2 S 0 8 4 2
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