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Three instruments have been evaluated for their ability to estimate the load conditions and efficiency of operating motors based solely on measurements of terminal voltage and current. Laboratory tests, compared to a high-accuracy dynamometer system were used to assess the instruments' accuracy. Field tests were conducted in a paper mill to determine the ease of use and lack of intrusion. In both laboratory and field tests the instruments were applied to 50-hp, 100-hp, and 200-hp 460-V induction motors. Data of the relative accuracies of the three instruments, as functions of motor load and supply voltage, are presented together with observations of ease and lack of intrusion in use. Index Terms--Efficiency, induction motors, in-service measurement.

The thermal capacity of totally enclosed fan-cooled converter-fed induction motors varies at the different operating frequencies. Main effects are due to the variation of the cooling airflow, the variation of iron losses, and eventually, the presence of harmonics. This paper presents the results of a complete evaluation of these effects and of the thermal torque at the different operating speeds. Index Terms--AC induction motors, frequency-controlled drives, thermal evaluation.

There are many 'black boxes' offered to advise the efficiency of installed motors. The major problem with most of those devices is that access to the motor is required; motors must be taken out of service to add instrumentation resulting in excess costs and time. This approach is to take readings at the Motor Control Center or motor starter, without having to disturb the motor or having to take an outage. The results obtained are more than adequate to study and estimate energy savings possibilities. Index Terms--Current, efficiency, energy savings, loading, motors.

There are many applications of induction motors to cyclic loading. Most motor manufacturers will perform calculations to obtain motor stator temperature rise for variable-load and cyclic loadings based on data provided. This paper will be a report of a testing program on totally enclosed fan-cooled induction motors where temperatures for loadings are measured. Index Terms--AC induction motors, duty cycles, thermal evaluation, thermal rating, winding temperature.

The IEEE Standard 841 was developed to identify additional specific features deemed necessary for application of induction motors in the petroleum and chemical industry. The Pulp and Paper Industry Committee (PPIC) of the IEEE Industry Applications Society has also been studying the IEEE Standard 841 for possible adoption by the pulp and paper industry. Members of the PPIC Ad Hoc Committee on IEEE 841 have suggested additional requirements to those in the existing standard. This paper discusses a comparison testing program conducted by the Motor Systems Resource Facility, an EPRI/BPA center at Oregon State University, Corvallis, in support of an industrial investigation of the available motors manufactured to the IEEE Standard 841. Seven major motor manufacturers participated in this study. Each manufacturer provided a 50-hp, a 100-hp, and a 200-hp 'standard' IEEE 841 motor for examination on delivery and IEEE 112 Method A efficiency testing. All of the motors were horizontal, three phase, 60 Hz, four pole, and 460 V (except one that was 575 V). Index Terms--Efficiency, IEEE Standard 841-2001, Motor Systems Resource Facility.