IEEE 115A-1987 pdf free.IEEE Standard Procedures for Obtaining Synchronous Machine Parametersby Standstill Frequency Response Testing.
IEEE 115A The measurements should be made with an instrument functionally equivalent to a transfer function analyzer,frequency response analyzer, Fourier analyzer, ordigital signal analyzer. Such instruments measurethe magnitudes and relative phase angles of twosignals and extract only the fundamental component from any distorted waveforms. In particular,a phaseangle measurement made by a zero crossing detector will not be satisfactory for the lowerfrequencies.
Typical Test Setups. (Refer to Fig 2.) Therelationships between the measured quantitiesand the desired variables are given in Section 5.An oscillator， sometimes an integral part of themeasuring instrument,provides the test signal.This goes to a power amplifier，the output ofwhich is connected to two terminals of the generator armature winding.The metering error of any measured transfer function should not exceedone percent at any point in the frequency range.The power arnplifier should create readily measurable signal levels for the armature and fieldwinding voltages and currents. Test currentsshould be small enough to avoid temperaturechanges in the armature, field, or damper circuitsduring the test. Voltages at the armature or fieldwinding terminals shall not exceed rated voltagelevels.As a general guide, test currents would notbe expected to exceed onehalf of one percent ofrated armature current (see 5.1).
Normal precautions to avoid overloading inputsand outputs of instruments should be observed.The impedance measured at the armature terminals at very low frequencies will be approximatelytwice the armature phase resistance. The maximum measured impedance will be approximately2(R2+ joL2), where R,and L, are the negativesequence resistance and inductance, and o is thehighest angular frequency used for the test. Boththe power amplifier and the measuring instrument should be suitable for this impedance range.4.4.2Measurement Accuracy. Reducing oreliminating the effect of contact resistances isvery important to the accuracy of the measurements, particularly on the armature winding.Thearmature current metering shunt should be bolteddirectly to the conductor in the isolated phasebus,as close to the generator terminals as possible; conducting grease should be used to enhancethe contact. An instrument having differentialinputs is preferred for making the measurements.Figure 3 shows the proper connection of the testleads for such a device. If an instrument withsingle ended inputs (common low side) is used,then the connections in Fig 4 are appropriate.IEEE 115A pdf download.