CSA C390-10:2016 pdf download.Test methods, marking requirements,and energy efficiency levels for three-phase induction motors
7.2.7 Efficiency interpolation
The efficiency at specific load points shall be determined by interpolation, using the values calculated in accordance with Clause 7.2.6 against the temperature-corrected
power output calculated in accordance with Clause 7.2.5. Interpolation techniques suitable for the shape of curve shall be used.
8 Marking
The nominal efficiency at 100% of the rated full-load shall be marked on the motor in accordance with Clause 9. In the case of dual-frequency motors, the frequency at which the efficiency was determined shall be indicated on the rating plate.
Note: Users should be aware that there could be local regulatory marking requirements in place.
9 Determining nominal efficiency
The nominal efficiency value shall be selected from Column A in Table 6 for motor operation at its rated voltage, frequency, and related load point. The nominal efficiency value selected from Column A shall be less than or equal to the average efficiency of a statistically significant population of motors of the same design. The measured efficiency of an individual motor shall be not less than the associated minimum value specified in Column B in Table 6 when tested in accordance with Clause 7.
The minimum nominal efficiency for standard output power ratings of 60 Hz motors is specified in Tables 2 and 3. The minimum nominal efficiency for 60Hz motors with rated output power values not specified in Tables 2 and 3 shall be determined as follows:
(a) The minimum nominal efficiency of a rated power at or above the midpoint between two consecutive power ratings shall be the higher of the two efficiencies.
(b) The minimum nominal efficiency of a rated power below the midpoint between two consecutive power ratings shall be the lower of the two efficiencies.
5.6.2 Power input
Power input to a three-phase motor shall be measured at the motor terminals using two single- phase wattmeters connected as in the two-wattmeter method, one three-phase wattmeter, or three single-phase wattmeters. The total power read on a wattmeter shall be reduced by the amount of the 12R loss in the voltage circuits of the instruments whenever this loss is a measurable portion of the total power read. Instruments used for power measurement shall be selected based on the requirements specified in Clause 5.3 at a power factor of 1.0, and shall be calibrated over the range of intended use, including measurements from 0.1 to 1 .0 power factor.CSA C390-10 pdf download.