GE 469 Instruction Manual

Also see for Masoneilan 469 Series: Instruction manual Instruction manual Instruction manual Communications guide Instruction manual

Contents

Application Example 469Motor Management RelayGetting Startedhttp://www.GEindustrial.com/multilin 1–19GE MultilinUse the above data to set the output relays to achieve breaker control; to set digitalinputs for breaker status, remote operations, remote status, and alarm indication.Assume that the communications between the station and the master control centerwill be done by the RTU. Alarms, status indication, and breaker commands will behard-wired from the relay to the RTU. Similar information could be exchangedbetween the RTU and the relay via an RS485 or RS422 Serial Link using the ModbusRTU protocol. Refer to GE Publication GEK-106491: 469 Communications Guide foradditional information.Instrument TransformerData• Voltage Transformers– 2 × Open Delta connected, ratio = 600:120 V– Motor System Voltage = 575 V• Phase CTsThe phase CTs should be chosen such that the FLC is 50% to 100% of CTprimary. Since the FLC is 347.5A a 350:5, or 400:5 CT may be chosen; 400:5 isa standard available size and so would probably be selected.• Ground CTFor high resistive grounded systems, sensitive ground detection is possible withthe 50:0.025 CT. Use a 1 A or 5 A secondary CT on solidly grounded or lowresistive grounded systems where the fault current is much higher. If a residualconnection is chosen, pickup levels and timers must be set with respect to theacceleration time. The chosen zero-sequence CT must be able to handle allpotential fault levels without saturating. In this example, 50:5A CT is selected.• Motor FLCSet the motor full load current to 348 A, as specified by the data sheets.Use the above data to set the relay system parameters, such as CT and VTconnections, VT secondary voltage, and CT and VT primary to secondary ratios.Motor Protection • Overload PickupThe overload pickup is set to the maximum allowed by the service factor of themotor. Since this motor has RTDs and the relay will be using the RTD biasfeature for enhanced protection, set the overload pickup to the highest settingof 1.25 x FLC for the motor service factor of 1.15. If service factor is unknown,assume 1.0.• Overload CurveSelect the standard overload curve to be just below the cold thermal limit togive maximum process uptime, without compromising protection.The best fitting curve is curve 7 (see figure below)