Eaton Magnum DS Technical Data Manual

Also see for Magnum DS: Instruction leaflet Instruction booklet Instructions Instructional Leaflet

Technical Data Effective: May 1998Page 20TD.44A.01.T.ECutler-HammerMagnum DSMetal-EnclosedLow-Voltage SwitchgearThe Following Provides Guidelines for Ground Fault Protection.System Advantages Disadvantages Equipment Available for ProtectionMain Breaker Tie Breaker Fdr. Breaker NotesUngrounded(3-Wire)Minimum distur-bance to servicecontinuity. Currentsfor the majority ofgrounds will be lim-ited to capacitancecharging current ofthe system. Canoperate with the firstground until it isremoved during aregular shutdown.Low cost. Supple-mental protectionfor an ungroundedsystem utilizing tripunit ground element.When ground detectorshows that a ground exists,corrective action must betaken at the earliest possi-ble shutdown. However,experience indicates thatthis attention is not alwayspossible. Therefore, thesesystems tend to operatewith one phase groundedthrough the first unclearedground. A high impedanceground on another part ofthe system would resultin low values of current,which would not operatea breaker phase trip, andcould produce fire damage.High voltages from arcinggrounds are possible.Lamp typeground detectoror grounddetecting volt-meters with orwithout voltagetransformers. Ifvoltage trans-formers areused, a groundalarm relay canbe added forremote or localalarming. 3-wireresidual protec-tion, minimumpickup.0.50 sec. timedelay. See SKNo. 1, No. 4,and No. 6.3-wire residualprotection, mini-mum pickup.0.35 sec. timedelay. Seesketch No. 4and No. 6.3-wire protec-tion, minimumpickup.0.22 sec. timedelay. See SKNo. 1, No. 4,and No. 6.20SolidGrounded20 20 Standard resid-ual ground pro-tection forsingle sourcesystems, andsource ground,per SK 5, formultiple groundsources. Mini-mum pickup.0.50 sec. timedelay.Ground 3-wireor 4-wire (asrequired) faultprotection. Mini-mum pickup.0.35 sec. timedelay. See SKNo. 4 or 5.Ground 3-wireor 4-wire (asrequired) faultprotection. Min-imum pickup.0.22 sec. timedelay or zerosequence cur-rent transformerfeeding Into tripunit. See SK No.1, No. 2, andNo. 6.This is the mostcommon systemin use today. Aslong as it is notnecessary tocoordinate withphase devicesdown the line, itwill give verygood main busand feeder pro-tection.HighResistanceGrounded(3-Wire)Ground fault currentis limited. Unground-ing can result inhigh voltages duringarcing grounds, andthis is corrected byhigh resistancegrounding. Can oper-ate with the firstground until it isremoved during aregular shutdown.Very sensitive detection isrequired to detect the lim-ited fault current. Whenthe ground detector showsthat a ground exists, cor-rective action must betaken at the earliest possi-ble shutdown. However,experience indicates thatthis attention is not alwayspossible, therefore, thesesystems tend to operatewith one phase groundedthrough the first unclearedground. A high impedanceground on another part ofthe system would result inlow values of current,which would not operate abreaker phase trip, andcould produce fire damage.Higher cost thanungrounded.Same as forungroundedexcept groundvoltage alarmrelay is con-nected acrossgrounding resis-tor, or currentrelay betweenresistor andground.Same as forungrounded.Same as forungrounded.Same as forungrounded.This system ismost effectivewhen suppliedwith a pulsingoption.Applicationwww . ElectricalPartManuals . com