Method B of IEEE 112 refers to loss-of-loss input-output and indirect measurement of load-dispersion losses. It is applied to horizontal squirrel cage polyphase type electric motors in the 1-250 hp range.
For the results of this procedure to be satisfactory, we must observe some recommendations, regarding the treatment of data and instruments and equipment used.
For electrical quantities we must adopt some procedures:
– All measured quantities must be in rms values; The power supply must provide balanced sinusoidal phase voltages; The frequency shall be maintained at ± 0,5% of the value required during the test; The voltages shall be measured at the motor terminals and the maximum voltage unbalance shall not exceed 0,5% of the average of the voltages; The currents of each phase of the motor must be measured; The input power of the three-phase machine shall be measured by two single-phase wattmeters, connected in accordance with the two wattmeters method; Stroboscopes or digital tachometers are recommended; We must adopt a safety procedure, since forces, tensions and currents that may be dangerous to health are involved. sealmaster bearings