IEEE 112-2017 pdf download

IEEE 112-2017 pdf download.IEEE Standard Test Procedure for Polyphase Induction Motors and Generators.
The errors of the transformers used shall not be greater than ±0.5% for general testing, or not greater than ±0.3% when the test results are for use with Efficiency Test Method B. When instrument transformers and instruments for measuring voltage, current, or power are calibrated as a system, the errors of the system shall not be greater than ±0.2% of full scale when the test results are for use with Efficiency Test Method B.
4.1.4 Voltage
Voltages shall he measured with the signal leads connected to the machine terminals. If local conditions will not permit such connections, the difference between the voltage at the machine terminals and the point of measurement shall be evaluated and the readings shall be corrected. The arithmetic average of the voltages shall be used in calculating machine perfbrrnance from the test data.
4.1.5 Current
The line currents to each phase of the motor shall be measured, and the arithmetic average value shall he used in calculating machine performance from the test data.
4.1.6 Power
Power input to a three-phase motor or power output from a three-phase generator may be measured by two single-phase wattmeters connected as in the two wattmeter method, one polyphase wattrneter, or three single-phase wattrneters. All power measurements and calculations, both electrical and mechanical, herein are in watts. On large machines it may be more practical to work with power quantities expressed in kilowatts. If the unit of measure is changed, take care that all affected values are properly converted.
4.1.7 Frequency
The instrument used to measure frequency shall have an accuracy of +0.05% of reading.
4.2 Resistance
4.2.1 Instrument selection
Calibrated high-accuracy instrumentation shall be used. Either analog instruments (such as a Kelvin bridge) or digital instruments may be used in testing.
The instruments shall bear record of calibration, within 1 2 months of the test, indicating limits of the error no greater than ±0.2% of full scale.
When a suitable automatic data-acquisition system is available, it may be used.
4.2.2 Resistance measurement
The procedures given in IEEE Std 118 and IEEE Std 119 should be used when measuring the resistance of the stator winding (and the rotor winding on wound-rotor machines).
4.3 Mechanical
4.3.1 Power
Mechanical power measurements shall be taken with the greatest care and accuracy. If a mechanical brake is to be used, the tare, if present. shall be carefully determined and compensated for. If dynamometer output measurements are used, coupling and bearing friction losses must be compensated for. An in-line torque transducer may be used to provide a direct measurement of torque at the test machine shaft. Properly sized dynamometers should be used, such that the coupling, friction, and windage losses of the dynamorneter (see the note below) measured at rated speed of the machine being tested should not be greater than 15% of the rated output of the machine being tested; and the dynamometer should be sensitive to a change of torque of 0.25% of the rated torque.
NOTE—A dynamometer is defined as a device for applying torque to the rotating member of the test machine. It is equipped with means for indicating torque and speed, and is not limited to a cradle base construction.6
The errors of the instrumentation used to measure mechanical torque shall not be greater than +0.2% of full scale. Additionally, for Efficiency Test Methods A and B, the operating range for the instrumentation shall be selected such that at rated full-load of the motor under test, the total error for torque measurements shall not exceed ±0.7% of the reading, which shall include all errors from all sources (load cell, torque arm length, etc.). The error of the instrumentation can be validated by calibration as a system or by calculation from the square root of the sum of the squares of the individual instrument errors. See Annex E for information on determining the total error of measurements.
4.3.2 Speed and slip
4.3.2.1 Instruments
Stroboscopic or digital tachometer methods shall be used to determine slip or speed. When a stroboscope is used to measure slip, the power supply for the stroboscope shall have the same frequency as the motor power supply.