Load Sharing Module - Home Mega Global Solution

Manual 26011Chapter 5Theory of OperationLoad Sharing ModuleIntroductionThis chapter describes the operation of the Load Sharing Module and its internalcircuits. Figure 1-4 is a block diagram of the circuits in the module.The Load Sharing Module senses the power output of a generator and provides a–4.5 to +1.5 Vdc signal to the speed control to adjust the power output of theengine-generator set to match the reference power level. The Load Sharing Modulecan also produce a droop condition (instead of isochronous load-sharing), makingit possible to connect the generator set in parallel with either a generator set whichis running isochronously, or with an infinite bus.Power SupplyThe power supply generates a regulated dc voltage for the operation of the circuitsin the Load Sharing Module. The power supply gets its power from two of thethree phase-potential connections which are made to the output of the generator setbeing controlled. Jumper wires on terminals 15 through 18 provide for selection ofinput voltages of either 95 to 130 Vac or 190 to 260 Vac. The plant wiringdiagram (Figure 1-3) shows these connections and jumpers. Do not connect inputsto terminals 15 through 18.Power SensorGenerator load is measured by the power-sensor circuit of the Load SharingModule. The power-sensor circuit senses current amplitude, and produces a loadsignal proportional to the current amplitude times the power factor. The potentialinput comes from potential transformers (PTs) and the current input comes fromthe current transformers (CTs). The circuit uses these two inputs to generate aload signal which is then filtered and sent to the controller circuit. The load signalvoltage of each generator set will be proportional to the percentage of rated loadon the generator set.Ammeters and voltmeters may be driven with the same PT and CT wires.Woodward 23