This chapter has shown that electrical techniques are powerful tools for the CM of electrical machines, particularly axial leakage flux, current and power, offering the potential to provide a general CM signal for the machine. The availability of high -quality, digitally sampled, mechanical vibration and electrical terminal 'performance' data from electrical machines opens the possibility for more comprehensive monitoring of the machine and prime mover or driven machine combinations. However, these signals generally require broad bandwidth (>50 kHz) and a high data rate for adequate analysis. Therefore, the principal difficulty of applying these techniques is the complexity of the necessary spectral analysis and interpretation of their content.

Chapter Contents:

• 9.1 Introduction
• 9.2 Generator and motor stator faults
• 9.2.1 Generator stator winding insulation detection
• 9.2.2 Stator current monitoring for stator faults
• 9.2.3 Brush-gear fault detection
• 9.2.4 Rotor-mounted search coils
• 9.3 Generator rotor faults
• 9.3.1 General
• 9.3.2 Earth leakage faults on-line
• 9.3.3 Turn-to-turn faults on-line
• 9.3.3.1 Air-gap search coils
• 9.3.3.2 Circulating current measurement
• 9.4 Motor rotor faults
• 9.4.1 General
• 9.4.2 Air-gap search coils
• 9.4.3 Stator current monitoring for rotor faults (MCSA)
• 9.4.4 Rotor current monitoring
• 9.5 Generator and motor comprehensive methods
• 9.5.1 General
• 9.5.2 Shaft flux
• 9.5.3 Stator and rotor currents
• 9.5.4 Power
• 9.5.5 Shaft voltage or current
• 9.5.6 Mechanical and electrical interaction
• 9.6 Conclusions

Inspec keywords: electric machines; power measurement; electric current measurement

Other keywords: general CM signal; power monitoring; flux monitoring; electrical machines; online current monitoring; electrical terminal performance data; prime mover; mechanical vibration

Subjects: d.c. machines; Current measurement; a.c. machines; Power and energy measurement