CSA C747-09:2016 pdf download.Energy efficiency test methods for small motors
5.4.1 General
The indicating instruments used in measurements shall be selected to give indications well up on the scale,that is, where a fraction of a division is easily estimated and where such a fraction is a small percentage of the value read. Indicating instruments shall have been calibrated over the range of their intended use within the past 1 2 months to limits of error no greater than +0.2% of full-scale deflection, traceable to national standards. Digital readout or computer printout instruments capable of the equivalent accuracy of measurement may be used.
Note: Further information on the use of instruments is given in IEEE 120.
5.4.2 Instrument transformers
When current and potential instrument transformers are used, corrections shall be made when necessary for ratio errors in voltage and current measurements (see Clauses 5.2 and 5.4.1). The ratio errors of instrument transformers shall be no greater than 0.3%.
5.4.3 Voltage
Voltages shall be read at the line connections. All measurements shall be performed only when the variation from rated voltage does not exceed +0. 5%. The three-phase motor test shall be performed only when the voltage unbalance from rated voltage does not exceed +0.5%.
Note: The percentage of voltage unbalance equals 100 times the maximum voltage deviation from the average voltage,divided by the average voltage (see Clause 5.2).
5.4.4 Current
Line current to the motor and any controlling or conditioning equipment shall be measured at the line connections. For the three-phase motor test, the line currents to each phase of the motor shall be measured. If the three-phase line currents are unequal, the arithmetic average shall be used in calculating motor performance from the test data.
5.4.5 Power
Input power shall be measured at the line connections. Input power shall be measured as follows:
(a) for the single-phase test, using a single-phase wattmeter; and
(b) for the three-phase test, using
(i) two single-phase wattmeters connected as in the two wattmeter method;
(ii) one polyphase wattmeter; or
(iii) three single-phase wattmeters.
The total input power read on a wattmeter shall be reduced by the amount of 12R (where I is current and R is resistance) in the voltage circuits of the instruments whenever such an amount is a measurable portion of the total power read.
Note: Further information on wattmeter connection methods is given in CAN/CSA-C60044-1 and CAN/CSA-C60044-2.
5.4.7 Dynamometer sizing
If dynamometer measurements are used, a correction factor shall be calculated to allow for coupling and bearing friction and inertia errors (see Clause 6.8). Dynamometers used for this test shall be sized such that the minimum load of the dynamometer, measured at the rated speed of the motor being tested, is no greater than 15% of the rated output of the motor.CSA C747-09 pdf download.