Toshiba GRL100-701B Instruction Manual page 433

2.10 Undervoltage element
a. Undervoltage element with current compensation (Phase selector)
(1) Undervoltage element (UVCV)
The UVCV element should be set not to work with the current of the power system.
UVCV < rated voltage × 0.7
= 63.5V × 0.7
= 44.5
(2) Reach setting (UVCZ)
The UVCZ element is set to the line impedance value:
UVCZ = 16.8 × (0.0197
= 0.41 ohms
b. VT failure supervision
The undervoltage element for VT failure supervision (UVFS, UVFG) is set to about 50% of
the rated voltage.
c. Weak infeed tripping function
The undervoltage element for weak infeed tripping (UVLS, UVLG) is set to 70% of the rated
voltage.
2.11 Time setting
a. Time delay setting for zone distance protection
b. Coordination time setting for protection signaling channel
This time setting is required only for the Blocking scheme. The time should be set larger than
the time delay of protection signaling equipment (PSE) including propagation time of PLC
(Power Line Carrier) or other communication link. The time setting should include an
operation margin of 5ms.
Element Setting
OCBF 5.1 (A)
TBF1 70ms
TBF2 140ms
2 2
) × 0.088
+ 0.2747
Element Setting
UVCV 45V
UVCZ 0.41
UVC θ
85
Element Setting
UVFS 52V
UVFG 30V
Element Setting
UVLS 77V
UVLG 45V
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