GE M60 Instruction Manual

Also see for M60: Communications manual Communications guide Instruction manual Instruction manual

Contents

5-114 M60 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUALSYSTEM SETUP CHAPTER 5: SETTINGS5These settings are critical for all features that have settings dependent on current measurements. When the relay isordered, the CT module must be specified to include a standard or sensitive ground input. As the phase CTs are connectedin wye (star), the calculated phasor sum of the three phase currents (IA + IB + IC = neutral current = 3Io) is used as the inputfor the neutral overcurrent elements. In addition, a zero-sequence (core balance) CT which senses current in all of thecircuit primary conductors, or a CT in a neutral grounding conductor can also be used. For this configuration, the groundCT primary rating must be entered. To detect low level ground fault currents, the sensitive ground input can be used. In thiscase, the sensitive ground CT primary rating must be entered. See chapter 3 for more details on CT connections.Enter the rated CT primary current values. For both 1000:5 and 1000:1 CTs, the entry would be 1000. For correct operation,the CT secondary rating must match the setting (which must also correspond to the specific CT connections used).The following example illustrates how multiple CT inputs (current banks) are summed as one source current. Given thefollowing current banks:• F1: CT bank with 500:1 ratio• F5: CT bank with 1000:1 ratio• M1: CT bank with 800:1 ratioThe following rule applies:Eq. 5-61 pu is the highest primary current. In this case, 1000 is entered and the secondary current from the 500:1 ratio CT isadjusted to that created by a 1000:1 CT before summation. If a protection element is set up to act on SRC 1 currents, thena pickup level of 1 pu operates on 1000 A primary.The same rule applies for current sums from CTs with different secondary taps (5 A and 1 A).5.5.1.2 Voltage banksSETTINGS  SYSTEM SETUP  AC INPUTS  VOLTAGE BANK F5(M5)Because energy parameters are accumulated, these values should be recorded and then reset immediately prior tochanging VT characteristics.Two banks of phase/auxiliary VTs can be set, where voltage banks are denoted in the following format (X represents themodule slot position letter):Xa, where X = {F, M} and a = {5}See the Introduction to AC Sources section at the beginning of this chapter for additional details.With VTs installed, the relay can perform voltage measurements as well as power calculations. Enter the PHASE VT F5CONNECTION made to the system as “Wye” or “Delta.” An open-delta source VT connection is entered as “Delta.” VOLTAGE BANK F5  PHASE VT F5CONNECTION: WyeRange: Wye, Delta PHASE VT F5SECONDARY: 66.4 VRange: 25.0 to 240.0 V in steps of 0.1 PHASE VT F5RATIO: 1.00 :1Range: 1.00 to 24000.00 in steps of 0.01 AUXILIARY VT F5CONNECTION: VagRange: Vn, Vag, Vbg, Vcg, Vab, Vbc, Vca AUXILIARY VT F5SECONDARY: 66.4 VRange: 25.0 to 240.0 V in steps of 0.1 AUXILIARY VT F5RATIO: 1.00 :1Range: 1.00 to 24000.00 in steps of 0.01SRC 1 F1 F5 M1+ +=