Breakdown of polyurethane hard-foam insulation under short-time HV stress

Koenig, D.; Bayer, Bernhard C.; Heller, Harry

doi:10.1109/14.90282

Cited by 9 publications

(1 citation statement)

References 4 publications

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“…The shorttime breakdown strength and PD behavior of polyurethane foam were determined, and a breakdown model for a microporous structure was developed based on the breakdown of a single pore. It is concluded that the partial discharges in few pores would not be sufficient to cause breakdown of the foam in a short time [3,4]. In 2003, polyurethane foam has been investigated, and its electrical properties have been studied under power frequency and lightning impulse voltages.…”

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The Performance of Polyurethane Foam at Different Humidity and Temperature Conditions for High Voltage Insulation

Argin

Karady

2005/2006 Pes Td

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The active parts of many hollow insulation systems are placed in SF 6 or N 2 filled insulating structures. The challenge with using these insulating gases initiated the replacement of them with polyurethane foam, which is frequently used in lowvoltage switchgears. Rigid pour polyurethane foam is presented to serve as a high voltage insulation material. The electrical properties are studied under power frequency and lightning impulse voltage. The performance of the proposed foam is determined at different humidity and temperature conditions.

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The Performance of Polyurethane Foam at Different Humidity and Temperature Conditions for High Voltage Insulation

Argin

Karady

2005/2006 Pes Td

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Impacts of moisture absorption on electrical properties of rigid polyurethane foam for composite post insulator of UHVDC transmission line

Sun

Wang

et al. 2021

International Journal of Electrical Power & Energy Systems

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Effects of void size and gas content on electrical breakdown in lightweight, mechanically compliant, void-filled dielectrics

Anderson

Lagasse

Russick

et al. 2002

Journal of Applied Physics

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Dielectric potting materials (encapsulants) are used to prevent air breakdown in high-voltage electrical devices. We report breakdown strengths in void-filled encapsulants, stressed with unipolar voltage pulses of the order of 10 μs duration. High strengths, on the order of 100 kV mm−1, are measured under these test conditions. The materials studied include low-density open celled gel-derived foams with cell sizes of 4 μm or less, closed celled CO2-blown polystyrene and urethane foams, and epoxies containing 48 vol % of hollow glass microballoon (GMB) fillers. These last specimens varied the void gas (N2 or SO2) and also the void diameters (tens to hundreds of μm). Our measurements are thought to be directly sensitive to the rate of field-induced ionization events in the void gas; however, the breakdown strengths of the materials tested appeared to vary in direct proportion with the conventional Paschen-law gas-discharge inception threshold, the electric stress at which gas-ionization avalanches become possible. The GMB-epoxy specimens displayed this type of dependence of breakdown strength on the void-gas density and void size, but the measurements were an order of magnitude above the conventional predictions. Small-celled foams also showed increased breakdown strengths with decreased cell size, although their irregular void geometry prevented a direct comparison with the more uniformly structured microballoon-filled encapsulants. The experimental observations are consistent with a breakdown mechanism in which the discharge of a few voids can launch a full breakdown in the composite material.

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Breakdown of polyurethane hard-foam insulation under short-time HV stress

Cited by 9 publications

References 4 publications

The Performance of Polyurethane Foam at Different Humidity and Temperature Conditions for High Voltage Insulation

The Performance of Polyurethane Foam at Different Humidity and Temperature Conditions for High Voltage Insulation

Impacts of moisture absorption on electrical properties of rigid polyurethane foam for composite post insulator of UHVDC transmission line

Effects of void size and gas content on electrical breakdown in lightweight, mechanically compliant, void-filled dielectrics

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