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Drop-off and pickup setting
2.18.1
Figure 2.17-1 shows the characteristic of the OVN element. The outer circle shows the
threshold of pick-up threshold voltage (PU), whereas the inner circle shows drop-off voltage
point (DO). The hatched area shows the operation area of the OVN.
For example, with regard to the OVN1 element, suppose the user sets a pick-up value in
P.U for setting [OVN1]. Then the user should set a drop-off value using setting [OVN1-DPR],
which configures the ratio of the PU to the DO.
Delay of the operation of the OVN element
2.18.2
The OVN element has a delay timer for the operation. For the OVN1 element, the user can set
a delay time using setting [TOVN1]. The user can find the delay timer in the OVN function
logic. (See Chapter 2.17.5)
Time characteristic
2.18.3
The OVN element has two characteristics between a voltage condition and an operation time;
hence, the user should select a mode either (i) definite (independent) time characteristic delay
or (ii) inverse (dependent) time characteristic delay. For the definite time characteristic delay,
the operation time is a constant. In the inverse time characteristic delay, the operation time
depends upon the level of the voltage condition.
Definite time characteristic (DT)
(i)
To operate the definite (independent) time delay, set scheme switch [OVN1-Timer] DT.
Resetting the OVN element is performed when a voltage falls below the drop-off voltage.
Invers time delay (IDMT)
(ii)
To operate the dependent (invers) time delay, set scheme switch [OVN1-Timer] IDMT.
Dropoff
0
Figure 2.18-1 Setting points of OVN
- 196 -
Pickup
V
V
6F2T0207 (0.01)
GRE200 (5,6)
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