Toshiba GR200 Series Instruction Manual page 364

FRQ features and characteristics
2.26.1
UF/OF characteristic
(i)
The UF and OF elements check the frequency every 5msec; they determines the frequency-
deviations whether the frequency is in under-frequency or over-frequency. Figure 2.26-1(a)
shows the UF characteristic; Figure 2.26-1(b) shows the OF characteristic; hatched area
reflects operation zone of the UF and the OF elements.
The user can select the stage 1 to detect either over-frequency state or under-frequency
state using scheme switch [FRQ1-Chara]. For example, If OverFrq is set for the scheme switch
[FRQ1-Chara], the stage 1 determines the over-frequency state when an over frequency is
observed (Figure 2.26-1(a)); the user can set the threshold value into [FRQ1]. Conversely, if
UnderFrq is set for the scheme switch, the stage 1 determines the under-frequency state when
an under frequency is observed (Figure 2.26-1(b)). The user can use a delay timer to postpone
to issue a trip signal using setting [TFRQ1].
Hz
o
Pickup voltage (FRQBLK)
a. Over frequency element at Stage 1
Figure 2.26-1 Characteristics of UF and OF elements (e.g. Stage 1 of FRQ)
Regarding the operation of the UF and OF elements, the user should notice the element
not to pick-up when the measured voltage is below the threshold value set with the [FRQBLK]
in positive sequence. Any operation of the FRQ function is blocked when an acquired voltage
is smaller than the pickup voltage to be set.
Enabling FRQ function
(ii)
The user should set On to enable the FRQ function using scheme switch [FRQ1-EN]. If the user
do not require the FRQ operation, Off should be set for the scheme switch.
OF stage 1
operation zone
V
- 341 -
Hz
UF stage 1
operation zone
o
Pickup voltage (FRQBLK)
b. Under frequency element at Stage 1
6F2S1914 (0.49)
V
GRL200 (Soft 033 & 037)