CHAPTER 5: SETTINGS GROUPED ELEMENTSC70 CAPACITOR BANK PROTECTION AND CONTROL SYSTEM – INSTRUCTION MANUAL 5-2355• Permissive functions — The undervoltage feature can be used to block the functioning of external devices byoperating an output relay when the voltage falls below the specified voltage setting. The undervoltage feature canalso 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 loadfrom 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 curveoperates when the voltage drops below the pickup level for a specified period of time. The time delay is adjustable from 0to 600.00 seconds in steps of 0.01. The undervoltage elements can also be programmed to have an inverse time delaycharacteristic.The undervoltage delay setting defines the family of curves shown as follows.Eq. 5-21whereT = operating timeD = undervoltage delay setting (D = 0.00 operates instantaneously)V = secondary voltage applied to the relayVpickup = pickup levelFigure 5-122: Inverse time undervoltage curvesAt 0% of pickup, the operating time equals the PHASE UNDERVOLTAGE DELAY setting.5.7.8.2 Phase undervoltage (ANSI 27P, IEC PTUV)SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) VOLTAGE ELEMENTS PHASE UNDERVOLTAGE1(3) PHASE UNDERVOLTAGE1 PHASE UV1FUNCTION: DisabledRange: Disabled, Enabled PHASE UV1 SIGNALSOURCE: SRC 1Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6 PHASE UV1 MODE:Phase to GroundRange: Phase to Ground, Phase to Phase PHASE UV1PICKUP: 1.000 puRange: 0.004 to 3.000 pu in steps of 0.001
