IEC TS 60349-3 pdf download – Electric traction – Rotating electrical machines for rail and road vehicles – Part 3: Determination of the total losses of converter-fed alternating current motors by summation of the component losses

IEC TS 60349-3 pdf download – Electric traction – Rotating electrical machines for rail and road vehicles – Part 3: Determination of the total losses of converter-fed alternating current motors by summation of the component losses
1scope and object
This technical specification applies to machines complying with lEC 60349-2.
The total losses of a converter-fed motor may be determined by summation of the componentlosses derived from no-load and load tests. The total input power is the sum of the power atthe fundamental frequency and at all other frequencies. In all practical cases the latter inputincludes the losses resulting from the voltage and current harmonics in the converter supplyby using suitable instrumentation it can be derived from measurement of the total andfundamental frequency power inputs when the machine is on load.
The losses supplied at the fundamental frequency cannot be measured directly and so arederived from measurement of the fundamental frequency load current and the fundamentalfrequency no-load power input.
2Instrumentation
The extra loss due to operation on a converter supply is obtained from the difference of thetotal and fundamental frequency power input on load.
The power inputs shall be measured simultaneously on each phase by a digital samplinginstrument. Measurement on all three phases is preferred but the two wattmeter method ispermissible as an alternative.
The total power is obtained from the product of voltage and current over a period of time andthe fundamental power from a Fourier transform using the same sampling.
lt is necessary to consider the accuracy of the whole instrument chain taking into accountboth amplification and phase shift errors over the desired frequency range.As the powerfactor of the harmonics is generally very low (less than 0,1 for voltage imposed asynchronoussystems) particular attention is drawn to the need for minimum phase angle errors.
At the time of publication of this technical specification，wattmeters accurate within thefollowing limits, at 0,08 power factor, were available:
below 2 kHz
士0,5%;
between 2 kHz and 20 kHz
士1,0 %;
between 20 kHz and 50 kHz
±2,0 %.
Instruments often contain attenuators compensated and adapted to them, but if an externalattenuator is used,it is desirable that it be accurate within the following limits given inTable 1.
NOTE The frequency range over which measurements are necessary depends on the harmonic content of theoutput from the particular converter used and should therefore be decided for each individual case.With theinstrumentation presently available, the overall accuracy of the total harmonic loss measurement is likely to be ofthe order of ±10 %, but as the loss is unlikely to exceed 3 % of the total power input, this will result in only 0,3 %error in the calculated torque, which is well within the permitted tolerance of -5 % specified in lEC 60349-2.
At the time of publication of this technical specification, current transformers are significantly less accurate at thelow power factors and high harmonic frequencies involved than non-inductive shunts，which can have a ratioaccuracy within ±1 %and a phase shift within 土0,2”.
3summation of losses
3.1 The total losses are the sum of the following component losses.
3.1.1 Losses supplied at the fundamental frequency on no-load (no-load losses):- losses in the active iron and other metal parts;
– losses due to friction and windage including the power absorbed by integral fans.
3.1.2 Losses which occur when the motor is supplied at the fundamental frequency andwhich vary with load (load dependent losses):
– PR losses in the stator windings;
– 2R losses in the rotor winding of asynchronous motors;
additional load losses (load loss) consisting of:
losses in the active iron and metal parts other than the conductors;
eddy current losses in the stator and rotor windings arising from current dependent fluxpulsation.
3.1.3 Losses supplied at other than the fundamental frequency.
3.1.4I2R and brush contact losses in the excitation circuit of synchronous motors.
3.2 Determination of the component losses
3.2.1 Asynchronous motors
3.2.1 .1 No-load losses supplied at the fundamental frequency