GE Multilin 745 Instruction Manual

Protection Schemes745Transformer Management RelayCommissioninghttp://www.GEindustrial.com/multilin7ñ20 GE MultilinPhase InstantaneousOvercurrent 1a) DescriptionThis procedure verifies that the Phase Instantaneous Overcurrent performancematches the in-service settings. The settings for these elements are found underthe S4 ELEMENTS !" PHASE OVERCURRENT setpoints menu. The testing occurs atcurrent multiples of at least five times the rated CT secondary value. Do not leavethe current signal on for more than a few seconds!b) Winding 1 ElementsTo ensure that only the Phase Instantaneous Overcurrent 1 element operates thetrip relays (and any other output relays) selected by the logic, disable all protectionfeatures except Phase Instantaneous Overcurrent 1. Use the general test setupshown in FIGURE 7ñ9: General Test Setup on page 7ñ18.Connect the current supply to terminals X = H1 and Y = G1 to test the Winding 1Phase A element. Monitor the appropriate output relays as per the relay FlexLogicôsettings.c) Pickup Level1. With the interval timer disabled, apply the current signal and increase its mag-nitude until the trip relay (and all selected auxiliary relays) operate. Comparethe measured operating level against the S4 ELEMENTS !" PHASE OC !" W1PHASE INST OC 1 !" W1 PHASE INST OC 1 PICKUP setpoint.2. Check that Trip, Pickup, and Phase A(C) LEDs turn on when the elementoperates. Check that one of the following messages is displayed:LATCHED a: W1 Phase Inst OC 1 or OPERATED a: W1 Phase Inst OC 13. Reduce the current until the element resets. The reset level should be 97% ofthe operate level. When the element resets, the Trip and Phase LEDs shouldremain on if the W1 PHASE INST OC 1 TARGET was selected as ìLatchedî.Otherwise, only the Trip LED should stay on.4. Reset indicators and clear messages.d) Operating TimeUsing the setup shown in FIGURE 7ñ9: General Test Setup on page 7ñ18 and theInterval Timer enabled, set the current level to 1.5 times the operating level of theelement. Apply current suddenly by closing the double-pole switch. Record theoperate time and compare it to the S4 ELEMENTS !" PHASE OC !" W1 PHASE INST OC 1!" W1 PHASE INST OC 1 DELAY setpoint value.e) Phase B and C ElementsIf the Phase A element performed correctly and met specifications, repeat thePickup Level portion of the above test for Phases B and C of Winding 1. For Phase B,X = H2 and Y = G2. For Phase C, X = H3 and Y = G3. The displayed messageshould change to indicate the correct phase, winding, and element that operated.f) Winding 2 and 3 ElementsBecause the Winding 2 and 3 elements can be set with completely differentparameters than the Winding 1 elements, it is necessary to repeat the full set oftests described above for each winding.Phase InstantaneousOvercurrent 2The Phase Instantaneous Overcurrent 2 elements are identical to the PhaseInstantaneous Overcurrent 1 elements. As such, the same test procedure can beused to verify their correct operation. Disable all protection features except thePhase Instantaneous Overcurrent 2 elements and follow the steps in the previoussection, making the appropriate changes for the display indications and outputrelays which are operated by the Phase Instantaneous Overcurrent 2 elements.The blocking from logic input, if enabled, can be tested as described inearlier tests for other elements.NOTE