Progress in Superconductivity and Cryogenics (한국초전도ㆍ저온공학회논문지)

The Korean Society of Superconductivity and Cryogenics (한국초전도저온학회)
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Contact resistance characteristics of 2G HTS coils with metal insulation

  • Sohn, M.H. (Superconductivity Research Center, Korea Electrotechnology Research Institute) ;
  • Ha, H. (Superconductivity Research Center, Korea Electrotechnology Research Institute) ;
  • Kim, S.K. (Superconductivity Research Center, Korea Electrotechnology Research Institute)
  • Received : 2018.12.05
  • Accepted : 2018.12.28
  • Published : 2018.12.31
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Abstract

The turn-to-turn contact resistance of 2G high temperature superconducting (HTS) coils with metal insulation (MI) is closely related to the stability of the coils, current charging rate and delay time [1]. MI coils were fabricated using five kinds of metal tapes such as aluminum (Al) tape, brass tape, stainless steel (SS) tape, copper (Cu)-plated tape and one-sided Cu-plated SS tape. The turn-to-turn contact surface resistances of co-winding model coils using Al tape, brass tape, and SS tape were 342.6, 343.6 and $724.8{\mu}{\Omega}{\cdot}cm^2$, respectively. The turn-to-turn contact resistance of the model coil using the one-sided Cu-plated SS tape was $ 248.8{\mu}{\Omega}{\cdot}cm^2$, which was lower than that of Al and brass tape. Al or brass tape can be used to reduce contact resistance and improve the stability of the coil. Considering strength, SS tape is recommended. For strength and low contact resistance, SS tape with copper plating on one side can be used.

Keywords

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Fig. 1. Schematic diagram of four types of HTS coils. (a) no insulation, (b) metal insulation coil, and (c) metal tapes for insulation.

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Fig. 2. Photo of model coils. (a) NI coil (NI50), (b) Al tape insulation coil (MI50-Al), (c) Brass tape insulation coil (MI50-Brass), (d) SS tape insulation coil (MI50-SS), (e) Cu-plated SS tape insulation coil (MI50-SS(2Cu)), and (f) one-sided Cu-plated SS tape insulation (MI50-SS(1Cu).3.

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Fig. 3. Photo of model coils and measurement array (a), and schematic drawing of the test circuit (b).

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Fig. 4. I-V characteristic curves of six types of model coils. (a) NI50 coil, (b) MI50-Al coil, (c) MI50-Brass coil, (d) MI50-SS, (e) MI50-SS(2Cu) coil, and (f) MI50-SS(1Cu) coil.

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Fig. 5. Variation of normalized magnetic field intensity in six model coils. (b) is an enlargement of (a)

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Fig. 6. Magnetic field intensity-time curves of three models with respect to current ramping rate. (a) MI50-Al coil, (b) MI50-Brass coil, and (c) MI50-SS(1Cu) coil.

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Fig. 7. Delay time according to the current ramp rate in six model coils. (b) is an enlargement of (a)

TABLE I SPECIFICATIONS OF FIVE TYPES OF METAL TAPES

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TABLE II SPECIFICATIONS OF SIX TYPES OF MODEL COILS

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References

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