• Title/Summary/Keyword: The single transformer

Search Result 380, Processing Time 0.027 seconds

A Study on the Characteristics of Circular Piezoelectric Transformner which has Multi-layered Crescent-Shaped Input Electrode (적층형 Crescent-Shaped Input Type 원형 압전변압기의 특성)

  • Jeong, Seong-Su;Park, Tae-Gone
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2006.11a
    • /
    • pp.223-224
    • /
    • 2006
  • This paper present a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. This transformer has multi-layered structure. The piezoelectric transformers operated m each transformer's resonance vibration mode. The electrodes and poling directions on commercialy available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor ($k_p,\;k_{15}$) becomes effective rather than the transverse mode coupling factor ($k_{31}$). The Resonance frequency is 65.22[kHz] and maximum voltage step-up ratio is 149. Multi-layered transformer has better efficiency and step-up ratio than the single-layered transformer.

  • PDF

Design of a 33 MVA HTS Transformer with OLTC (OLTC를 고려한 33 MVA 초전도 변압기 설계)

  • Choi, J.H.;Lee, S.W.;Park, M.J.;Kim, W.S.;Choi, K.D.
    • Proceedings of the KIEE Conference
    • /
    • 2006.07b
    • /
    • pp.885-886
    • /
    • 2006
  • We have proposed a 100 MVA, 3 phases, 154 kV class HTS transformer which will substitute for 60 MVA conventional transformer. In this paper, we designed conceptually the structure of the superconducting windings of a single phase 33 MVA transformer. The power transformer of 154 kV class has a tertiary winding besides primary and secondary windings. So the HTS transformer should have the 3rd superconducting winding, it makes the cost of the HTS transformer high and the efficiency low. Further more we considered On Load Tap Changer (OLTC) in HTS power transformer. OLTC equipment is required for fitting to a power transformer by which the voltage ratio between the windings can be varied while the transformer is on load. We analyzed the electrical characteristics of the HTS transformer such as magnetic stress and AC loss.

  • PDF

A Cost-Effective, Single-Phase Line-Interactive UPS System that Eliminates Inrush Current Phenomenon for Transformer-Coupled Loads

  • Bukhari, Syed Sabir Hussain;Atiq, Shahid;Lipo, Thomas A.;Kwon, Byung-il
    • Journal of Electrical Engineering and Technology
    • /
    • v.11 no.3
    • /
    • pp.675-682
    • /
    • 2016
  • Sudden voltage drops and outages frequently disturb the operation of sensitive loads for domestic, commercial, and industrial use. In some cases, these events may even impair the functioning of relevant equipment. To maintain power under such conditions, a UPS system is usually installed. Once a disturbance happens at the grid side, the line-interactive UPS system takes over the load to prevent an interruption. But, due to magnetic saturation of the transformer, a significant inrush current may occur for the transformer-coupled loads during this transition. The generation of such transient currents may in turn decrease the line voltage and activates over-current protecting devices of the system. In this work, a cost-effective, line-interactive UPS system is proposed that eliminates the inrush current phenomenon associated with transformer-coupled loads. The strategy was implemented by connecting a standard current-regulated voltage source inverter (CRVSI) to the secondary winding of the load transformer. During any transient condition at the grid side, the load current is monitored and regulated to achieve either seamless compensation of the load current or complete transferal of load from grid to the inverter. Experimental results were obtained for a prototype under all possible operating conditions so as to validate the performance of the proposed topology.

The Safety Survey Analysis and Consideration of Small Transformer (소형 변압기 안전성 실태 분석 및 고찰)

  • Kim, Sung-Sam
    • Journal of the Korean Society of Safety
    • /
    • v.29 no.2
    • /
    • pp.1-6
    • /
    • 2014
  • In this paper, safety certification products and safety condition of small transformer is analyzed in industries field and educational facilities. In transformer of 50places, absolute majority is step down transformer to measure of instrument. Most transformers were below 5kVA and 1~3kVA capacity was the mainstream. In industries field, 5 transformers were found without safety certification according to the Electrical Appliances Safety Control Act as cheap product prefer and lack of safety consciousness. Mark & number, voltage, date of manufacture of safety certification must show item of certification. However date of manufacture showed in product of 18%, 9places. As result of thermal imaging camera, running temperature of transformer was showed in below of target temperature. However as a narrow space of transformer and wall, power cable was touched on a ventilating flue in transformer. It was simple carelessness case that surface fouling and temperature ageing of transformer accelerate. Power poor connection, neglect of transformer in production equipment, fall damage by setup incongruity and ground omission were found in case of illogicality item of transformer.

Design of a IMVA Single-Phase HTS Power Transformer

  • Kim, Sung-Hoon;Kim, Woo-Seok;Park, Chan-Bae;Hahn, Song-yop;Park, Kyeong-Dal;Joo, Hyeong-Gil;Hong, Gye-Won
    • Progress in Superconductivity
    • /
    • v.4 no.1
    • /
    • pp.86-89
    • /
    • 2002
  • In this paper, the design of a IMVA single-phase high temperature superconducting(HTS) power transformer with BSCCO-2223 HTS tapes is presented. The rated voltages of each sides of the transformer are 22.9 ㎸ and 6.6 ㎸, respectively The winding of 1MVA HTS transformer is consisted of double pancake type HTS windings, which have advantages of insulation and distribution of high voltage, and are cooled by subcooled liquid nitrogen of 65K. Four HTS tapes were wound in parallel for the windings of low voltage side and the four parallel conductors are transposed. The design of 1MVA HTS transformer, a shell type core made of laminated silicon steel plate is chosen, and the core is separated with the windings by a cryostat with a room temperature bore. The cryostat made of non-magnetic and non-conducting material and a liquid nitrogen sub-cooling system is designed in order to maintain the coolant's temperature of 65K. For electromagnetic analysis of 1MVA HTS transformer, a finite element method of an axis of symmetry is used. The maximum perpendicular component of magnetic flux density of pancake windings is about 0.15T. And through analyzing the magnetic field distribution, an optimal winding arrangement of 1MVA HTS transformer is obtained.

  • PDF

A High efficiency Multi output PDP Power system with Single transformer structure (Multi 출력단을 Single Transformer 로 통합 설계한 고효율 PDP 용 전원시스템)

  • Park, Sang-Gab;Roh, Chung-Wook;Han, Sang-Kyu;Hong, Sung-Soo;SaKong, Sug-Chin;Kim, Jong-Hae;Lee, Hyo-Bum
    • Proceedings of the KIPE Conference
    • /
    • 2007.07a
    • /
    • pp.280-282
    • /
    • 2007
  • 기존 PDP 전원 시스템은 일반적으로 두 개의 절연형 Transformer 를 사용하여 유지전원($V_S$)과 어드레스 전원($V_A$), Multi단 전원($V_M$) 으로 구성된다. 이들 각 전력 변환 회로에 Transformer 및 제어 IC 가 사용되므로, 효율 저감 및 원가 상승, 소자 스트레스 등의 단점을 가지고 있다. 본 논문에서는 절연형 Transformer 한 개로 PDP 전원시스템을 구동하는 방식에 대해 제안한다. 제안된 방식은 DC/DC 전력단의 고효율 동작 및 신뢰성 개선은 물론 부피, 크기를 줄여 원가 저감에 기여한다. 또한, 제안된 방식은 PDP 구동 방식의 하나인 Address Display Separation Method (ADSM) 에 적합하다. 기존 방식과 제안된 방식을 비교하고 이론적 분석과 실험을 통해 제안된 방식의 우수성을 확인 하였다.

  • PDF

A Study on the Characteristics of Circular Piezoelectric Transformer which has Crescent-shaped Input Type (Crescent-shaped Input Type 원형압전변압기의 특성 연구)

  • Jeong, Seong-Su;Park, Tae-Gone
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
    • /
    • v.19 no.7
    • /
    • pp.644-649
    • /
    • 2006
  • This paper presents a new disk-type piezoelectric transformer. The input side of the transformer has a crescent-shaped electrode and the output side has a focused poling direction. The piezoelectric transformers operated in each transformer's resonance vibration mode. The electrodes and poling directions on commercially available piezoelectric ceramic disks were designed so that the planar or shear mode coupling factor $(k_p\;k_{15})$ becomes effective rather than the transverse mode coupling factor $(k_{31})$. ANSYS finite element code was used to analyze transformer behavior and to optimize electrode and poling configurations. The voltage step-up ratio of the proposed transformer has been markedly improved in comparison with that of the equivalent rectangular(Rosen) type. A single layer prototype transformer, $20\sim30mm$ in diameter and $1.0\sim3.5mm$ thick, was fabricated, such as step-up ratio, power transformation efficiency, and temperature were measured. While the transformer was driving a Cold Cathode Fluorescent Lamp(CCFL), the temperature field of the transformer was also observed.

Design of an HTS Transformer with OLTC (OLTC를 고려한 고온 초전도 변압기의 설계)

  • Choi, J.H.;Lee, S.W.;Park, M.J.;Joo, H.G.;Han, J.H.;Hahn, S.Y.;Choi, K.D.
    • Progress in Superconductivity and Cryogenics
    • /
    • v.9 no.1
    • /
    • pp.67-71
    • /
    • 2007
  • HTS transformers which have been developed until now had only fundamental structures. Among the auxiliary functions of conventional transformers, voltage regulating is the most important one. For the voltage regulation, conventional transformers are equipped with on load tap changers (OLTCS). In this paper, we describe the possibility of the HTS transformer with OLTC. For the case study, we designed a single phase 33 MVA HTS transformer with OLTC. It is one of three individual HTS transformers which composes a 3 phase, 100 MVA transformer. It is expected to substitute for a 3 phase, 60 MVA conventional transformer in Korea. The parameters of an HTS transformer are varied due to the gap length between primary and secondary windings. The length was decided for the transformer to have the impedance of 12 %. Its size was limited to the one of the conventional transformer. The characteristics of the HTS transformer were analyzed in both case of having OLTC and not.

Zero Sequence Impedance of Yg-Yg Three Phase Core Type Transformer (Yg-Yg 3상 내철형 변압기의 영상분 임피던스 분석)

  • Jo, Hyunsik;Cho, Sungwoo;Shin, Changhoon;Cha, Hanju
    • The Transactions of The Korean Institute of Electrical Engineers
    • /
    • v.65 no.6
    • /
    • pp.940-945
    • /
    • 2016
  • In this paper, zero sequence equivalent circuit of Yg-Yg three phase core-type transformer is analyzed. Many problems by iron core structure of the three phase transformer due to asymmetric three phase lines, which includes line disconnection, ground fault, COS OFF, and unbalanced load are reported in the distribution system. To verify a feasibility of zero sequence impedance of Yg-Yg type three phase transformer, fault current generation in the three phase core and shell-type Yg-Yg transformer is compared by PSCAD/EMTDC when single line ground fault is occurred. As a result, shell-type transformer does not affect the flow of fault current, but core-type transformer generate an adverse effect by the zero sequence impedance. The adverse effect is explained by the zero sequence equivalent circuit of core-type transformer and Yg-Yg type three phase core-type transformer supplies a zero sequence fault current to the distribution system.

Temperature Characteristic Analysis according to Variation of Properties of Transformer Insulating Oil (변압기 절연유의 물성치 변화에 따른 온도특성해석)

  • Kim, Ji-Ho;Rhee, Wook
    • The Transactions of the Korean Institute of Electrical Engineers P
    • /
    • v.63 no.4
    • /
    • pp.327-332
    • /
    • 2014
  • In this paper, the temperature distribution according to the property change of the insulating oil of the power transformer and max temperature were predicted through the ductility interpretation which heat-flow is coupled. By using CFD (Computation Fluid Dynamics) for the interpretation, the temperature distribution of 154kV the class single phase power transformer was predicted. The power loss causing the temperature rise of the transformer was changed to the heat source and we used as the input value for the heat-flow analysis. The temperature distribution was predicted according to the change of the density, specific heat, thermal conductivity and viscosity, that is the ingredient having an effect on the temperature rise of the transformer oil. The mineral oil of 4 kinds used in domestic and international based on the interpreted result was selected and the temperature distribution according to each load and Hot Spot temperature was predicted.