• Title/Summary/Keyword: Positive Temperature Coefficient

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Development on Electrical Fire Prevention System of Small Size and High Speed by using PTC Thermistor (PTC 서미스터를 이용한 소형 고속응성의 전기화재 방재시스템 개발)

  • Kwak, Dong-Kurl
    • Journal of the Microelectronics and Packaging Society
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    • v.15 no.1
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    • pp.51-58
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    • 2008
  • This paper is studied on a prevention system for electrical fire and electrical faults by using electrical temperature characteristic of PTC thermistor. The PTC thermistor has characteristic of positive resistivity temperature coefficient according to the temperature variation, which is construction of a regular square and cube demarcation with $BaTiO_3$ ceramics of positive temperature coefficient. Also PTC shows the phenomenon which is rapidly increased in the resistivity if the temperature is increased over Curie temperature point. This paper is proposed on a protective control system used with temperature sensor of PTC thermistor. The proposed prevention system will prevent electrical fires due to electric short circuit faults or overload faults. And the prevention system will solve the problems that circuit breakers to be commonly used at existing are happened frequently electrical fires and electrical disasters due to incapable operation, weak reliability and low speed response. Some experimental results of the proposed apparatus are confirmed to the validity of the analytical results.

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PTCR Characteristics of Multifunctional Polymeric Nano Composites (PTCR 나노 복합기능 소재의 전류 차단 특성 연구)

  • 김재철;박기헌;서수정;이영관;이성재
    • Polymer(Korea)
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    • v.26 no.3
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    • pp.367-374
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    • 2002
  • Electrical characteristics of crystalline polymer composites filled with nano-sized carbon black particle were studied. The developed composite system exhibited a typical positive temperature coefficient resistance (PTCR) characteristic, where the electrical resistance sharply increased at a specific temperature. The PTCR effect was sometimes followed by a negative temperature coefficient resistance (NTCR) feature with temperature, which seemingly caused by the coagulation of nano-sized carbon black particles in the excessive quantity. The PTCR temperature was controlled by the carbon black content and the external voltage. The change of electric conductivity was shown as a function of carbon black content, and the resistance was constant when the carbon black content was over 20 wt%. The room-temperature resistance was maintained by a repeated heating and cooling. The excellent PTCR characteristic was demonstrated by the low resistance in the initial stage and the instantaneous heating capability.

A Study on the Ignition Characteristics of the Electric Mosquito Repellent Mat (화재사례를 통한 전자 모기향의 발화특성에 관한 연구)

  • Choi, Jae-Sung;Choi, Seung-Bok;Min, Se-Hong;Choi, Don-Mook
    • Fire Science and Engineering
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    • v.23 no.5
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    • pp.196-205
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    • 2009
  • Electric mosquito repellent mats can be ignited by damage of cables, partial disconnection, overload. tracking and so on. In this study, we examined the structure of mosquito repellent mat, positive temperature coefficient(PTC) thermistor, used for heating element and phenomenological characteristics of remains, obtained on the scene of fires. After reappearance ignition test of PTC thermistors, we did comparison analysis them. And we could confine that the feature of heating plate and the shape of bursting were same.

A Study on Development of Electric Safety Control Apparatus by Using Thermal Characteristics of PTC Thermistor (PTC 서미스터의 온도특성을 이용한 전기안전 제어장치 개발에 관한 연구)

  • Kwak, Dong-Kurl;Jung, Do-Young
    • Fire Science and Engineering
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    • v.21 no.4
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    • pp.65-71
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    • 2007
  • This paper is studied on a protective control system for electrical fire and electrical faults by using electrical and thermal characteristics of PTC thermistor. The PTC thermistor has characteristic or positive resistivity temperature coefficient according to the temperature variation, which is construction of a regular square and cube demarcation with $BaTiO_3$ Ceramics of positive temperature coefficient. Also PTC thermistor shows the phenomenon which is rapidly increased in the resistivity if the temperature is increased over Curie temperature point. This paper is proposed on a protective control system used PTC thermistor which is protected from electrical fire due to electric short circuit faults or overload faults. Some experimental results of the proposed electric safety control apparatus are confirmed to the validity of the analytical results.

A Study on Electric Safety Control Device for Prevention of Over Current and Short Circuit Faults (과전류 및 단락사고 방지용 전기안전 제어장치에 관한 연구)

  • Jo, Si-Hwan;Kwak, Dong-Kurl;Jung, Do-Young;Shim, Jae-Sun;Kim, Jung-Sook
    • Proceedings of the KIEE Conference
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    • 2008.07a
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    • pp.2100-2101
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    • 2008
  • This paper is studied on a protective control system for electrical fire and electrical faults due to over current or electric short circuit faults by using electrical thermal characteristics of PTC (Positive Temperature Coefficient) thermistor and current response characteristics of high sensitive reed switch. The PTC thermistor has characteristic of positive resistivity temperature coefficient according to the temperature variation, which is construction of a regular square and cube demarcation with BaTiO3_Ceramics of positive temperature coefficient. Also PTC thermistor shows the phenomenon which is rapidly increased in the resistivity if the temperature is increased over Curie temperature point, and reed switch, which is used for electrical fault current sensing devices, have a excellent characteristic of response velocity in degree of ${\mu}s{\sim}ms$ that sensing magnetic flux in proportion to dimension of line current. This paper is proposed on a protective control system use PTC thermistor and reed switch for sensor which is protected from electrical fire due to overload faults or electric short circuit faults. Some experimental results of the proposed electric safety control device are confirmed to the validity of the analytical results.

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A 2-stage CMOS operational amplifier with temperature compensation function for sensor signal processing (센서 신호 처리를 위한 온도 보상 기능을 가진 2단 CMOS 연산 증폭기)

  • Ha, Sang-Min;Seo, Sang-Ho;Shin, Jang-Kyoo
    • Journal of Sensor Science and Technology
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    • v.18 no.4
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    • pp.280-285
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    • 2009
  • In this paper, we designed a 2-stage CMOS operational amplifier with temperature compensation function using 2-poly 4-metal 0.35 $\mu$m standard CMOS technology. Using two bias circuits, the positive temperature coefficient(PTC) and the negative temperature coefficient(NTC) of the bias circuit are canceled out each other. When reference current circuit is simulated that it has a temperature coefficient of -150 ppm/$^{\circ}C$ with a temperature change from 0 $^{\circ}C$ to 120 $^{\circ}C$. Also the proposed circuit has a temperature coefficient of -0.011 dB/$^{\circ}C$ of DC open loop gain with the same temperature range.

Investigations of Temperature Effect on the Conduction Mechanism of Electrical Conductivity of Copolymer/Carbon Black Composite

  • El Hasnaoui, M.;Kreit, L.;Costa, L.C.;Achour, M.E.
    • Applied Microscopy
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    • v.47 no.3
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    • pp.121-125
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    • 2017
  • This study deals the prediction of temperature effect on low-frequency dispersion of alternating current (AC) conductivity spectra of composite materials based on copolymer reinforced with carbon black (CB) particles. A sample of ethylene butylacrylate loaded with 13% of CB particles were prepared and investigated using the impedance spectroscopy representation in the frequency range from 40 Hz to 0.1 MHz and temperature range from $20^{\circ}C$ to $125^{\circ}C$. The dielectric constant, ${\varepsilon}^{\prime}$, and dielectric losses, ${\varepsilon}^{{\prime}{\prime}}$, were found to decrease with increasing frequency. The frequency dependence of the AC conductivity follows the universal power law with a large deviation in the high frequency region, the positive temperature coefficient in resistivity effect has been observed below the melting temperature which makes this composite potentially remarkable for industrial applications.

A Study on the PTC Thermistor Characteristics of Polyethylene and Polyethylene Copolymer Composite Systems in Melt and Solution Manufacturing Method (용액 및 용융 가공방법에 따른 PE 및 PE 공중합물의 PTC 서미스터 특성 연구)

  • 김재철;박기헌;남재도
    • Polymer(Korea)
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    • v.26 no.6
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    • pp.812-820
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    • 2002
  • The positive temperature coefficient (PTC) characteristics of polymer composites were investigated with the nano-sized carbon black particles using solution tasting and melt compounding methods. The polymeric PTC composites should the electrical threshold at 35 wt% for the melt compounding method and 40 wt% for the solution casting method. The ethylene vinylacetate copolymer (EVA) composite showed a gradual increase of resistance as a function of temperature and showed a maximum at the polymer molting point. The resistance of the high-density polythylene (HDPE) composite remains unchanged with temperature but started to Increase sharply near the melting point of HDPE and showed a maximum resistance at the melting point of HDPE. The dispersion of nano-sized carbon black particles was investigated by scanning electron microscopy (SEM) and low resistance after electrical threshold, and both methods exhibited a well dispersed morphology. When the electric current was applied to the PTC composites, the resistance started increasing at the curie temperature and further increased until the trip temperature was roached. Then the resistance remained stable over the trip temperature. The secondary increase started at T$\sub$m/ of matrix polymer and kept increasing up to the trip temperature.

Analyses and improvement of fuel temperature coefficient of rock-like oxide fuel in LWRs from neutronic aspect

  • Shelley, Afroza
    • Nuclear Engineering and Technology
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    • v.52 no.6
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    • pp.1156-1163
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    • 2020
  • Fuel temperature coefficient (FTC) of PuO2+ZrO2 (ROX) fueled LWR cell is analyzed neutronically with reactor- and weapons-grade plutonium fuels in comparison with a U-free PuO2+ThO2 (TOX), and a conventional MOX fuel cells. The FTC value of a ROX fueled LWR is smaller compared to a TOX or a MOX fueled LWRs and becomes extremely positive especially, at EOL. This is because when fuel temperature is increased, thermal neutron spectrum is shifted to harder, which is extreme at EOL in ROX fuel than that in TOX and MOX fuels. Consequently at EOL, 239Pu and 241Pu contributes to positive fuel temperature reactivity (FTR) in ROX fuel, while they have negative contribution in TOX and MOX fuels. The FTC problem of ROX fuel is mitigated by additive ThO2, UO2 or Er2O3. In ROX-additive fuel, the atomic density of fissile Pu becomes more than additive free ROX fuel especially at EOL, which is the main cause to improve the FTC problem. The density of fissile Pu is more effective to decrease the thermal spectrum shifts with increase the fuel temperature than additive ThO2, UO2 or Er2O3 in ROX fuel.

The Electrical Property of Polymer Matrix Composites Added Carbon Powder

  • Shin, Soon-Gi
    • Korean Journal of Materials Research
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    • v.25 no.12
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    • pp.678-682
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    • 2015
  • The electrical property of polymer matrix composites with added carbon powder is studied based on the temperature dependency of the conduction mechanism. The temperature coefficient of the resistance of the polymer matrix composites below the percolation threshold (x) changed from negative to positive at 0.20 < x < 0.21; this trend decreased with increasing of the percolation threshold. The temperature dependence of the electrical property(resistivity) of the polymer matrix composites below the percolation threshold can be explained by using a tunneling conduction model that incorporates the effect of the thermal expansion of the polymer matrix composites into the tunneling gap. The temperature coefficient of the resistance of the polymer matrix composites above the percolation threshold has a positive value; its absolute value increased with increasing volume fraction of carbon powder. By assuming that the electrical conduction through the percolating paths is a thermally activated process and by incorporating the effect of thermal expansion into the volume fraction of the carbon power, the temperature dependency of the resistivity above the percolation threshold can be well explained without violating the universal law of conductivity.