Rotating electrical machines - Part 25: AC electrical machines used in power drive systems - Application guide

IEC TS 60034-25:2022 describes the performance characteristics of AC electrical machines for use on converter supplies. For electrical machines specifically designed for converter duty application design features are defined. It also specifies the interface parameters and interactions between the electrical machine and the converter including installation guidance as part of a power drive system, but except for the voltage at the power interface which is described in IEC TS 61800-8. This fourth edition of IEC TS 60034-25 cancels and replaces the third edition, This edition includes the following significant technical changes with respect to the previous edition:
a. The definitions of a converter capable motor and a converter duty motor are added.
b. Clause 18 modified to include the performance expectations of a converter capable motor.
c. Clause 8 modified to update shaft currents section.
d. Annex D added to define the derating requirements.

General Information

Status
Published
Publication Date
26-Jun-2022
Technical Committee
Current Stage
PPUB - Publication issued
Completion Date
27-Jun-2022
Ref Project

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IEC TS 60034-25
Edition 4.0 2022-06
TECHNICAL
SPECIFICATION
colour
inside
Rotating electrical machines –
Part 25: AC electrical machines used in power drive systems – Application guide
IEC TS 60034-25:2022-06(en)
---------------------- Page: 1 ----------------------
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---------------------- Page: 2 ----------------------
IEC TS 60034-25
Edition 4.0 2022-06
TECHNICAL
SPECIFICATION
colour
inside
Rotating electrical machines –
Part 25: AC electrical machines used in power drive systems – Application guide
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 29.160.01 ISBN 978-2-8322-2003-0

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 60034-25:2022 © IEC 2022
CONTENTS

FOREWORD ........................................................................................................................... 9

INTRODUCTION ................................................................................................................... 11

1 Scope ............................................................................................................................ 12

2 Normative references .................................................................................................... 12

3 Terms and definitions .................................................................................................... 13

4 System characteristics ................................................................................................... 16

4.1 General ................................................................................................................. 16

4.2 System information ............................................................................................... 16

4.3 Torque/speed considerations ................................................................................ 16

4.3.1 General ......................................................................................................... 16

4.3.2 Torque/speed capability ................................................................................. 17

4.3.3 Electrical machine rating................................................................................ 18

4.3.4 Limiting factors on torque/speed capability .................................................... 18

4.3.5 Safe operating speed, over-speed capability and over-speed test .................. 19

4.3.6 Cooling arrangement ..................................................................................... 19

4.3.7 Voltage/frequency characteristics .................................................................. 20

4.3.8 Resonant speed bands .................................................................................. 20

4.3.9 Duty cycles .................................................................................................... 21

4.4 Electrical machine requirements ........................................................................... 21

5 Losses and their effects (for induction electrical machines fed from voltage source

converters) .................................................................................................................... 24

5.1 General ................................................................................................................. 24

5.2 Location of the additional losses due to converter supply and ways to reduce

them ..................................................................................................................... 25

5.3 Converter features to reduce the electrical machine losses ................................... 26

5.3.1 Reduction of fundamental losses ................................................................... 26

5.3.2 Reduction of additional losses due to converter supply .................................. 26

5.4 Use of filters to reduce additional electrical machine losses due to converter

supply ................................................................................................................... 27

5.5 Temperature influence on life expectancy ............................................................. 27

5.6 Determination of electrical machine efficiency ....................................................... 28

6 Acoustic noise, vibration and torsional oscillation .......................................................... 28

6.1 Acoustic noise ...................................................................................................... 28

6.1.1 General ......................................................................................................... 28

6.1.2 Changes in noise emission due to changes in speed ..................................... 28

6.1.3 Magnetically excited noise ............................................................................. 29

6.1.4 Sound power level determination and limits ................................................... 31

6.2 Vibration (excluding torsional oscillation) .............................................................. 31

6.2.1 General ......................................................................................................... 31

6.2.2 Vibration level determination and limits .......................................................... 32

6.3 Torsional oscillation .............................................................................................. 32

7 Electrical machine insulation electrical stresses ............................................................ 33

7.1 General ................................................................................................................. 33

7.2 Causes ................................................................................................................. 33

7.3 Winding electrical stress ....................................................................................... 35

7.4 Limits and responsibility ........................................................................................ 36

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IEC TS 60034-25:2022 © IEC 2022 – 3 –

7.4.1 Electrical machines design for low voltage (≤ 1 000 V) .................................. 36

7.4.2 Electrical machines designed for medium and high voltage (> 1 000 V) ......... 37

7.5 Methods of reduction of voltage stress .................................................................. 37

7.6 Insulation stress limitation ..................................................................................... 38

8 Bearing currents ............................................................................................................ 39

8.1 Sources of bearing currents in converter-fed electrical motors .............................. 39

8.1.1 General ......................................................................................................... 39

8.1.2 Circulating currents due to magnetic asymmetry ............................................ 39

8.1.3 Electrostatic build-up ..................................................................................... 39

8.1.4 High-frequency effects in converter operation ................................................ 39

8.2 Generation of high-frequency bearing currents ...................................................... 41

8.2.1 Common mode voltage .................................................................................. 41

8.2.2 Motor HF equivalent circuit and the resulting bearing current types ............... 42

8.2.3 Circulating current ......................................................................................... 44

8.2.4 Rotor ground current ..................................................................................... 44

8.2.5 Electrostatic Discharge Machining (EDM) currents ......................................... 45

8.3 Consequences of excessive bearing currents........................................................ 46

8.4 Preventing high-frequency bearing current damage .............................................. 50

8.4.1 Basic approaches .......................................................................................... 50

8.4.2 Other preventive measures ............................................................................ 51

8.4.3 Other factors and features influencing the bearing currents ........................... 54

8.5 Additional considerations for electrical motors fed by high voltage source

converters ............................................................................................................. 54

8.5.1 General ......................................................................................................... 54

8.5.2 Bearing protection of cage induction, brushless synchronous and

permanent magnet electrical motors .............................................................. 54

8.5.3 Bearing protection for slip-ring electrical motors and for synchronous

electrical motors with brush excitation ........................................................... 54

8.6 Bearing current protection for electrical motors fed by high-voltage current

source converters ................................................................................................. 55

9 Installation ..................................................................................................................... 55

9.1 Earthing, bonding and cabling ............................................................................... 55

9.1.1 General ......................................................................................................... 55

9.1.2 Earthing ......................................................................................................... 55

9.1.3 Bonding of electrical machines ...................................................................... 55

9.1.4 Electrical machine power cables for high switching frequency

converters ..................................................................................................... 56

9.2 Reactors and filters ............................................................................................... 61

9.2.1 General ......................................................................................................... 61

9.2.2 Output reactors .............................................................................................. 61

9.2.3 Voltage limiting filter (du/dt filter) .................................................................. 61

9.2.4 Sinusoidal filter .............................................................................................. 61

9.2.5 Electrical machine termination unit ................................................................ 61

9.3 Power factor correction ......................................................................................... 62

9.4 Integral electrical machines (integrated electrical machine and drive

modules) ............................................................................................................... 63

10 Additional considerations for permanent magnet (PM) synchronous electrical

machines fed by voltage source converters ................................................................... 63

10.1 System characteristics .......................................................................................... 63

10.2 Losses and their effects ........................................................................................ 63

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– 4 – IEC TS 60034-25:2022 © IEC 2022

10.3 Noise, vibration and torsional oscillation ............................................................... 64

10.4 Electrical machine insulation electrical stresses .................................................... 64

10.5 Bearing currents ................................................................................................... 64

10.6 Particular aspects of permanent magnets ............................................................. 64

11 Additional considerations for cage induction electrical machines fed by high

voltage source converters .............................................................................................. 64

11.1 General ................................................................................................................. 64

11.2 System characteristics .......................................................................................... 65

11.3 Losses and their effects ........................................................................................ 66

11.3.1 Additional losses in the stator and rotor winding ............................................ 66

11.3.2 Measurement of additional losses .................................................................. 66

11.4 Noise, vibration and torsional oscillation ............................................................... 66

11.5 Electrical machine insulation electrical stresses .................................................... 67

11.5.1 General ......................................................................................................... 67

11.5.2 Electrical machine terminal overvoltage ......................................................... 67

11.5.3 Stator winding voltage stresses in converter applications............................... 67

11.6 Bearing currents ................................................................................................... 69

12 Additional considerations for synchronous electrical machines fed by voltage

source converters .......................................................................................................... 69

12.1 System characteristics .......................................................................................... 69

12.2 Losses and their effects ........................................................................................ 69

12.3 Noise, vibration and torsional oscillation ............................................................... 69

12.4 Electrical machine insulation electrical stresses .................................................... 69

12.5 Bearing currents ................................................................................................... 70

13 Additional considerations for cage induction electrical machines fed by block-type

current source converters .............................................................................................. 70

13.1 System characteristics (see Figure 35 and Figure 36) ........................................... 70

13.2 Losses and their effects ........................................................................................ 71

13.3 Noise, vibration and torsional oscillation ............................................................... 73

13.4 Electrical machine insulation electrical stresses .................................................... 73

13.5 Bearing currents ................................................................................................... 73

13.6 Additional considerations for six-phase cage induction electrical machines ........... 74

14 Additional considerations for synchronous electrical machines fed by LCI ..................... 74

14.1 System characteristics .......................................................................................... 74

14.2 Losses and their effects ........................................................................................ 75

14.3 Noise, vibration and torsional oscillation ............................................................... 75

14.4 Electrical machine insulation electrical stresses .................................................... 75

14.5 Bearing currents ................................................................................................... 75

15 Additional considerations for cage induction electrical machines fed by pulsed

current source converters (PWM CSI) ............................................................................ 76

15.1 System characteristics (see Figure 39) ................................................................. 76

15.2 Losses and their effects ........................................................................................ 77

15.3 Noise, vibration and torsional oscillation ............................................................... 77

15.4 Electrical machine insulation electrical stresses .................................................... 77

15.5 Bearing currents ................................................................................................... 77

16 Wound rotor induction (asynchronous) electrical machines supplied by voltage

source converters in the rotor circuit .............................................................................. 77

16.1 System characteristics .......................................................................................... 77

16.2 Losses and their effects ........................................................................................ 77

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IEC TS 60034-25:2022 © IEC 2022 – 5 –

16.3 Noise, vibration and torsional oscillation ............................................................... 78

16.4 Electrical machine insulation electrical stresses .................................................... 78

16.5 Bearing currents ................................................................................................... 78

17 Other electrical machine/converter systems ................................................................... 78

17.1 Drives supplied by cyclo-converters ...................................................................... 78

17.2 Wound rotor induction (asynchronous) electrical machines supplied by

current source converters in the rotor circuit ......................................................... 80

18 Special consideration for standard fixed-speed induction electrical machines in the

scope of IEC 60034-12 when fed from voltage source converter and motor

requirements to be considered a converter capable motor ............................................. 80

18.1 General ................................................................................................................. 80

18.2 Torque derating during converter operation ........................................................... 82

18.2.1 General ......................................................................................................... 82

18.2.2 Self-cooled motors ......................................................................................... 83

18.2.3 Non self-cooled motors .................................................................................. 84

18.3 Losses and their effects ........................................................................................ 84

18.4 Noise, vibrations and torsional oscillation ............................................................. 84

18.5 Electrical machine insulation electrical stresses .................................................... 84

18.5.1 General ......................................................................................................... 84

18.5.2 Converter capable motor ............................................................................... 85

18.6 Bearing currents in converter capable motors ....................................................... 85

18.7 Speed range mechanical limits.............................................................................. 86

18.7.1 General ......................................................................................................... 86

18.7.2 Maximum speed ............................................................................................ 86

18.7.3 Minimum speed ............................................................................................. 86

18.8 Overload torque capability .................................................................................... 87

18.9 Excess overload current limits .............................................................................. 87

18.9.1 General ......................................................................................................... 87

18.9.2 Converter capable motor ............................................................................... 87

18.10 Volts/Hz ratio and voltage boost............................................................................ 87

18.11 Resonance............................................................................................................ 87

18.12 Hazardous area operation ..................................................................................... 87

18.12.1 General ......................................................................................................... 87

18.12.2 Converter capable motor ............................................................................... 88

18.13 Unusual service conditions ................................................................................... 89

18.13.1 Converter capable motors .............................................................................. 89

18.13.2 Unusual converter-fed applications ................................................................ 89

19 Additional considerations for synchronous reluctance electrical machine fed by

voltage source converters .............................................................................................. 89

19.1 System characteristics .......................................................................................... 89

19.2 Losses and their effects ........................................................................................ 89

19.3 Noise, vibration and torsional oscillation ............................................................... 89

19.4 Electrical machine insulation electrical stresses .................................................... 89

19.5 Bearing currents ................................................................................................... 89

19.6 Particular aspects of synchronous reluctance electrical machines ......................... 90

Annex A (informative) Converter characteristics ................................................................... 91

A.1 Converter control types ......................................................................................... 91

A.1.1 General ......................................................................................................... 91

A.1.2 Converter type considerations ....................................................................... 92

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– 6 – IEC TS 60034-25:2022 © IEC 2022

A.2 Converter output voltage generation (for voltage source converters) ..................... 92

A.2.1 Pulse width modulation (PWM) ...................................................................... 92

A.2.2 Hysteresis (sliding mode) .............................................................................. 93

A.2.3 Influence of switching frequency .................................................................... 93

A.2.4 Multi-level converters..................................................................................... 94

A.2.5 Parallel converter operation ........................................................................... 95

Annex B (informative) Output characteristics of 2 level voltage source converter

spectra ................................................................................................................................. 96

Annex C (informative) Voltages to be expected at the power interface between

converter and electrical machine ......................................................................................... 100

Annex D (informative) Speed and harmonic capability of converter capable induction

motor .................................................................................................................................. 104

D.1 General ............................................................................................................... 104

D.2 Harmonic capability of converter capable motors ................................................ 104

D.3 Speed capability and derating in variable torque application ............................... 105

D.4 Speed capability and derating in a constant torque application ........................... 105

Bibliography ........................................................................................................................ 107

Figure 1 – Torque/speed capability ....................................................................................... 17

Figure 2 – Current required by motor .................................................................................... 18

Figure 3 – Examples of possible converter output voltage/frequency characteristics ............. 20

Figure 4 – Example for the dependence of the electrical machine losses caused by
harmonics P related to the losses P at operating frequency f , on the switching
h, f1 1

frequency f in case of 2 level voltage source converter supply ............................................ 25

Figure 5 – Example of measured losses P as a function of frequency f and supply type ...... 26

Figure 6 – Additional losses ∆P of an electrical machine (same electrical machine as

Figure 5) due to converter supply, as a function of pulse frequency f , at 50 Hz

rotational frequency .............................................................................................................. 27

Figure 7 – Relative fan noise as a function of fan speed ....................................................... 29

Figure 8 – Vibration modes of the stator core ........................................................................ 30

Figure 9 – Typical surges at the terminals of an electrical machine fed from a PWM

converter .............................................................................................................................. 33

Figure 10 – Typical voltage surges on one phase at the converter and at the electrical

machine terminals (2 ms/division) ......................................................................................... 34

Figure 11 – Individual short rise-time surge from Figure 10 (1 μs/division) ............................ 34

Figure 12 – Definition of the rise-time t of the voltage pulse at the electrical machine

terminals ............................................................................................................................... 35

Figure 13 – First turn voltage as a function of the rise-time ...............................................

...

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