Degradation Effects on Energy Absorption Capability and Time to Failure of Low Voltage Metal Oxide Varistors

Khanmiri, Dawood Talebi; Ball, Roy; Lehman, Brad

doi:10.1109/tpwrd.2016.2629442

Cited by 29 publications

(9 citation statements)

References 22 publications

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“…This significant reduction in TOV current over applied pulses forms a distinct contrast to the degradation trend of leakage current, which normally relates a higher leakage current with a degraded MOV [12]. This flip of degradation trend has been illustrated with a crossover in V-I curves between new and degraded MOVs at 0.01 A [33]. Moreover, attributing to the limited 100 ms duration of TOV stress, the TOV current kept a generally decreasing trend throughout tests.…”

Section: (B)mentioning

confidence: 94%

Evaluation Tests of Metal Oxide Varistors for DC Circuit Breakers

Rockhill

Zhang

et al. 2022

IEEE Open J. Power Energy

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With emerging technologies and products in power semiconductors and ultrafast mechanical switches, direct-current circuit breakers (DCCBs) have been developing rapidly. Yet the metal-oxide varistors (MOVs), being the indispensable DCCB components, are less analyzed and tested so far. Generally, MOVs in DCCBs are used to dissipate energy and limit overvoltage surges during switching events. This emerging application of MOVs calls for new design procedures and evaluation tests to ensure MOV performance under non-standard stresses and repetitive energy pulses. In this paper, online-monitored stress endurance tests are performed on MOVs that are employed in a 12 kV DCCB. Most MOVs have endured the DCCB-derived stresses for about 3500 pulses with little variation in their voltage-current characteristics, while only one fails after 1000 pulse tests and gets damaged by a shunt conductive channel. Different from conventional operating points of MOVs in their voltage-current characteristics, the MOVs in DCCB applications are found to work routinely in the temporary overvoltage (TOV) region with a decreasing TOV current over time. As these behaviors of MOVs are scarcely reported in the literature or covered by their datasheets, this study presents one of the first publicly available endurance test data that address the knowledge gaps about energy-dissipating MOVs in switchgear applications.

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Section: (B)mentioning

confidence: 94%

Evaluation Tests of Metal Oxide Varistors for DC Circuit Breakers

Rockhill

Zhang

et al. 2022

IEEE Open J. Power Energy

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“…However, it must be noted that thermal degradation occurs in MOVs due to repetitive surge pulses; hence, failure can occur in the long run. More information about MOV degradation patterns can be found in [58]. Next, we aim to estimate the energy distribution within the supercapacitor (SC) sub-circuit of the STS circuit.…”

Section: Energy Dissipation In Varistorsmentioning

confidence: 99%

Laplace Transform-Based Modelling, Surge Energy Distribution, and Experimental Validation of a Supercapacitor Transient Suppressor

Silva Thotabaddadurage

2023

Technologies

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The discovery of the transient-surge-withstanding capability of electrochemical dual-layer capacitors (EDLCs) led to the development of a unique, commercially beneficial circuit topology known as a supercapacitor transient suppressor (STS). Despite its low component count, the new design consists of a transient-absorbing magnetic core which takes the form of a coupled inductor placed between the AC-main- and load-side varistors. With an introduction to the structural features of metal oxide varistors (MOVs), gas tubes, thyristors, and EDLCs, this research presents a frequency (S)-domain analysis of an STS circuit to accurately model the surge propagation through its coupled inductor. Transient energy distribution trends among STS components are estimated in this paper, with an emphasis on peak energies absorbed and dissipated by the various inductive, capacitive, and resistive circuit elements. Moreover, this study reveals STS transient-mode test waveforms validated by a standard lightning surge simulator with supporting simulation plots based on LTSpice numerical techniques. Both experimental and simulation results are consistent, with the analytical findings showing 90% of the peak transient propagating through the primary coil, whereas only 10% is shared into the secondary coil of the coupled inductor. In addition, it is proven that the two STS MOVs dissipate over 50% of the transient energy for a standard 6 kV/3 kA combinational surge, while the magnetic core absorbs over 20% of the energy. All test procedures conducted during this research adhere to IEEE C62.41/IEC 61000-4-5 standards.

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“…12, it is apparent that if the MOV of each stage has the same clamping voltage rating, that will result in different amount of energy absorption for MOVs in different stage. This leads to uneven thermal stress on the MOVs, which can result in failure of the MOV operation reducing the breaker life-time and reliability [19]- [21].…”

Section: Energy Absorption In Movsmentioning

confidence: 99%