Conference Paper

Progress on IEC 60034-18-42 for Qualification of Stator Insulation for Medium-Voltage Inverter Duty Applications

GE Consumer & Ind., Peterborough
DOI: 10.1109/PCICON.2007.4365806 Conference: Petroleum and Chemical Industry Technical Conference, 2007. PCIC '07. IEEE
Source: IEEE Xplore

ABSTRACT

There is an industry need for suitable methods to qualify medium-and high-voltage stator insulation systems for inverter duty applications. Technical Specification (TS) IEC 60034-18-42 is being written to address the unique requirements of form-wound micaceous systems to withstand inverter pulses, characterized by elevated voltage, fast rise times, and high frequency impulse repetition rates. These machines do not operate under the same ageing conditions as those supplied by sinusoidal power or as random windings supplied by pulse-width modulated (PWM) drives. Depending on the specific waveform characteristics observed at the machine terminals, the ground wall insulation, turn insulation, corona suppression and end winding voltage grading systems are significantly affected by ageing factors such as partial discharge (PD) and elevated temperature. The TS offers technically sound guidelines to manufacturers and users describing test procedures to prove the electrical and thermal reliability of these components. Like IEC 60034-18-41 (for low voltage systems) it will significantly impact construction and testing of NEMA motors. This paper describes the theoretical and practical considerations of the specification.

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    • "It must however be ensured that system availability, lifetime, and hazardous area requirements are not compromised due to insulation damage associated with inverter-induced overvoltages . Motor insulation requirements associated with MV ASDs are well documented in the literature and the recently published IEC 60034-18-42 standard [9], [10]. The standard (and literature) focuses, however, on the expected waveforms at the motor terminals, considering cable effects, MV pulsewidthmodulation (PWM) waveforms, and the reflective-wave phenomenon . "
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    ABSTRACT: Simulations and field tests indicate that unacceptable motor-terminal overvoltages and waveform shapes can occur in the normal operating range with high-output-voltage multilevel drive systems. These waveforms (if unattended) can result in premature motor insulation failures. A case study of an 11-kV multilevel system is presented. Simulations and calculations confirm the theory of resonance overvoltages. Different solution possibilities are analyzed. Further simulations and investigations are performed to determine the optimal carrier frequency. Test results confirm that the proposed modification has the desired effect, with waveforms well within limits stipulated by international standards. Simplified equations and recommendations are provided to determine suitable application solutions. Further simulated resonance case studies are presented, considering the effect of the system configurations, motor size, and cable length. Suitable carrier-frequency selection methods are presented to solve the problem.
    Preview · Article · Sep 2009 · IEEE Transactions on Industry Applications
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    • "It must however be ensured that system availability, lifetime, and hazardous area requirements are not compromised due to insulation damage associated with inverter-induced overvoltages . Motor insulation requirements associated with MV ASDs are well documented in the literature and the recently published IEC 60034-18-42 standard [9], [10]. The standard (and literature) focuses, however, on the expected waveforms at the motor terminals, considering cable effects, MV pulsewidthmodulation (PWM) waveforms, and the reflective-wave phenomenon . "
    [Show abstract] [Hide abstract]
    ABSTRACT: Simulations and high voltage field tests indicate that unacceptable and unexpected motor terminal overvoltages and waveform shapes can occur in the normal operating range with multilevel drive systems. These waveforms (if unattended) would have resulted in premature motor insulation failures. A case study of an 11 kV multilevel system is discussed. Simulations and calculations confirm the theory of resonance overvoltages. Different solution possibilities are analyzed. Further simulations and investigations are performed to determine the optimal carrier frequency. Test results confirm that the proposed modification has the desired effect; with waveforms well within limits stipulated by international standards. Simplified equations and recommendations are provided to determine suitable application solutions.
    Preview · Conference Paper · Jun 2007
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