GE C70 Instruction Manual page 379

CHAPTER 5: SETTINGS
• Permissive functions — The undervoltage feature can be used to block the functioning of external devices by
operating an output relay when the voltage falls below the specified voltage setting. The undervoltage feature can
also be used to block the functioning of other elements through the block feature of those elements.
• Source transfer schemes — In the event of an undervoltage, a transfer signal can be generated to transfer a load
from its normal source to a standby or emergency power source.
The undervoltage elements can be programmed to have a definite time delay characteristic. The definite time curve
operates when the voltage drops below the pickup level for a specified period of time. The time delay is adjustable from 0
to 600.00 seconds in steps of 0.01. The undervoltage elements can also be programmed to have an inverse time delay
characteristic.
The undervoltage delay setting defines the family of curves shown as follows.
where
T = operating time
D = undervoltage delay setting (D = 0.00 operates instantaneously)
V = secondary voltage applied to the relay
V = pickup level
pickup
At 0% of pickup, the operating time equals the
5.7.8.2 Phase undervoltage (ANSI 27P, IEC PTUV)
SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  VOLTAGE ELEMENTS  PHASE UNDERVOLTAGE1(3)
 PHASE
 UNDERVOLTAGE1
C70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL
Figure 5-110: Inverse time undervoltage curves
PHASE UNDERVOLTAGE DELAY
PHASE UV1

FUNCTION: Disabled
PHASE UV1 SIGNAL

SOURCE: SRC 1
PHASE UV1 MODE:

Phase to Ground
PHASE UV1

PICKUP: 1.000 pu
GROUPED ELEMENTS
setting.
Range: Disabled, Enabled
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
Range: Phase to Ground, Phase to Phase
Range: 0.004 to 3.000 pu in steps of 0.001
Eq. 5-21
5
5-213