Toshiba GR200 Series Instruction Manual page 325

Drop-off and pickup characteristic
2.21.1
Figure 2.21-1 shows the characteristic of the OV element. The outer circle shows the threshold
of pick-up threshold voltage (PU), whereas the inner dotted circle shows drop-off voltage point
(DO). The hatched area shows the operation area of the OV.
For example, with regard to the OV1 element, suppose the user sets a pick-up value in
P.U for setting [OV1]. Then the user should set a drop-off value using setting [OV1-DPR], which
configures the ratio of the PU to the DO.
Delay for the operation of the OV element
2.21.2
The OV element has a delay timer for the operation. For the OV1 element, the user can set a
delay time using setting [TOV1]. The user can find the delay timer in the OV function logic.
(See section 2.21.5)
Time characteristic
2.21.3
The OV 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 DT for scheme switch [OV1-Timer].
Resetting the OV element is performed when a voltage falls below the drop-off voltage.
Invers time characteristic (IDMT)
(ii)
To operate the dependent (invers) time delay, set IDMT for scheme switch [OV1-Timer].
Pick-up characteristic
The operate time of the inverse (dependent) time characteristic is inversely proportional to the
Dropoff
Figure 2.21-1 Characteristic of OV element
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Pickup
V
V
0
6F2S1914 (0.49)
GRL200 (Soft 033 & 037)