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CSA C747-09 pdf free download
CSA C747-09 pdf free download.Energy efficiency test methods for small motors.
5.4 Instrument selection
The indicating instruments used in measurements shall be selected to give indications well up on the scale, that is, where a fraction of a dMsion 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 12 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%.
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 o( voltage unbalance equals 100 times the mwumum voltage diation from the average voltage. divided by the overage voltage (see Clause 5.2).
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.
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 C.4N/CSA-C60044.2.CSA C747-09 pdf free download.
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