5-142 L90 Line Differential Relay GE Multilin5.5 GROUPED ELEMENTS 5 SETTINGS55.5.13 VOLTAGE ELEMENTSa) MAIN MENUPATH: SETTINGS !" GROUPED ELEMENTS ! SETTING GROUP 1(6) !" VOLTAGE ELEMENTSThese protection elements can be used for a variety of applications such as:Undervoltage Protection: For voltage sensitive loads, such as induction motors, a drop in voltage increases the drawncurrent which may cause dangerous overheating in the motor. The undervoltage protection feature can be used to eithercause a trip or generate an alarm when the voltage drops below a specified voltage setting for a specified time delay.Permissive Functions: The undervoltage feature may be used to block the functioning of external devices by operating anoutput relay when the voltage falls below the specified voltage setting. The undervoltage feature may also be used to blockthe functioning of other elements through the block feature of those elements.Source Transfer Schemes: In the event of an undervoltage, a transfer signal may be generated to transfer a load from itsnormal 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 oper-ates when the voltage drops below the pickup level for a specified period of time. The time delay is adjustable from 0 to600.00 seconds in steps of 10 ms. The undervoltage elements can also be programmed to have an inverse time delaycharacteristic. The undervoltage delay setting defines the family of curves shown below.Figure 5ñ85: INVERSE TIME UNDERVOLTAGE CURVES# VOLTAGE ELEMENTS## PHASE# UNDERVOLTAGE1 See page 5ñ143.MESSAGE # PHASE# UNDERVOLTAGE2 See page 5ñ143.MESSAGE # PHASE# OVERVOLTAGE1 See page 5ñ144.MESSAGE # NEUTRAL OV1# See page 5ñ145.MESSAGE # AUXILIARY UV1# See page 5ñ146.MESSAGE # AUXILIARY OV1# See page 5ñ147.D=5.0 2.0 1.00.02.04.06.08.010.012.014.016.018.020.00 10 20 30 40 50 60 70 80 90 100 110% of V pickupTime (seconds)where: T = Operating TimeD = Undervoltage Delay Setting(D = 0.00 operates instantaneously)V = Secondary Voltage applied to the relayVpickup = Pickup LevelAt 0% of pickup, the operating time equals theUNDERVOLTAGE DELAY setting.T D1 VV pickup------------------– ----------------------------------=NOTE
