내진형 수배전반을 위한 지진격리장치 설계

고동우 대한건축학회지회연합회 2020 대한건축학회연합논문집 Vol.22 No.3

As the social interest in seismic design of telecommunication facilities increased in the early 2000s, studies on the development of seismic electrical cabinet in ordinary buildings began to be conducted. In Korea, various methods have been suggested to improve the seismic performance of electrical cabinet for ordinary building, but only a few of them are actually used. In this study, seismic isolation device was developed, based on the results of the nonlinear time history analysis, to increase the seismic performance of the electrical cabinet, and the seismic performance was verified by shaking table tests. The results of the analysis and tests are as follows; (1) Proposed simplified model showed the possibility of being usefully used to grasp the dynamic characteristics of the electrical cabinet. (2) As a result of shaking table tests, the maximum bottom shear force was reduced by 55% and operated normally to satisfy the demanded performance of the electrical cabinet. (3) A series of processes performed in this study, seismic isolator can be useful in the development of seismic isolators for electrical cabinet in the future. 2000년대초에 전기통신설비의 내진설계에 대한 사회적 관심이 증가함에 따라 보통 건물의 내진형 수배전반 개발에 대한 연구가 수행되기 시작하였다. 우리나라에서도 보통 건물에 설치되는 수배전반의 내진성능을 향상시키기 위한 다양한 방법들이 제시되어 왔으나, 이들 방법들 가운데 실제 활용된 사례는 일부에 불과하다, 본 연구에서는 비선형 시간이력해석 결과를 바탕으로 수배전반의 내진성능을 높이기 위한 지진격리장치를 개발한 후, 진동대실험을 통해 성능을 검증하였다. 이를 통한 결론은 다음과 같다. (1) 수배전반을 등가의 동적특성을 나타내는 캔틸레버로 모델링하여 비선형 시간 이력 해석을 수행한 결과, 단순화한 해석모델은 수배전반의 동적특성을 파악하는데 유용하게 활용될 수 있는 가능성을 보여주었다. (2) 비선형해석결과 나타난 물성을 바탕으로 지진격리장치를 설계한 후 수배전반에 대한 진동대 실험 결과와 비교하였다. 최대 밑면전단력은 55% 감소하여 수배전반의 요구성능을 만족하였으며, 진동대실험결과 수배전반은 정상적으로 작동하여 주어진 요구성능을 만족하였다. (3) 이상의 과정을 통해 단순캔틸레버로 수배전반의 해석모델을 단순화하고, 이를 통해 지진격리장치의 요구성능을 도출하는 일련의 과정은 향후 유사한 수배전반의 격리장치 개발에서 유용하게 사용될 수 있음을 알 수 있다.

콘크리트 재료의 불확실성을 고려한 전기 캐비닛-앵커 시스템의 지진 취약도 분석

손호영 ( Son Ho-young ),전법규 ( Jeon Bub-gyu ),정우영 ( Jung Woo-young ),주부석 ( Ju Bu-seog ) 한국복합신소재구조학회 2021 복합신소재구조학회논문집 Vol.12 No.6

배전기 캐비닛은 발전소와 같은 플랜트 시설에서 전자기기 혹은 시스템 컨트롤러 등을 보관하는 역할을 한다. 전기 캐비닛이 지진과 같은 외부하중에 의해 손상될 경우 시스템 장애 혹은 운영 중단이 발생할 수 있다. 안정적이고 지속가능한 에너지 공급을 위해 외부 하중에 의한 전기 캐비닛의 안전성 평가는 매우 중요하다. 전기 캐비닛은 주로 콘크리트 슬래브에 앵커로 지지되기 때문에 앵커의 지지력 상실로 인해 전기 캐비닛이 손상될 수 있다. 콘크리트 재료는 다양한 불확실성이 존재하며 변동성이 다른 재료에 비해 큰 편이다. 따라서 본 연구에서는 선행연구에서 개발된 전기 캐비닛-앵커 시스템의 유한요소 모델을 이용하여 콘크리트 재료의 불확실성을 고려한 지진 취약도 평가를 수행하였다. 30개의 콘크리트 재료 모델을 라틴 하이퍼큐브 샘플링을 이용하여 샘플링하였으며 울진 지역의 등재해도 스펙트럼을 만족하는 인공지진을 적용하여 시간이력 해석을 수행하였다. 앵커의 응력과 캐비닛 최상단의 변위를 한계상태로 정의하였다. 지진 취약도 분석 결과 0.2g를 초과할 때 앵커의 응력 및 캐비닛 최상단 변위가 정해진 한계상태를 초과하는 것으로 나타났으며 대부분 0.5g에서 파괴되는 것으로 나타났다. 추후 연구에서는 지진의 불확실성과 재료의 불확실성을 동시에 고려하여 지진 취약도 평가를 수행하고자 한다. The electric cabinet serves to store electronic devices or system controllers in plant facilities such as power plants. If the electrical cabinet is damaged by an external load such as an earthquake, a system failure or plant shutdown may occur. For a stable and sustainable energy supply, it is very important to assess the safety of the electric cabinet using an external load. Electrical cabinets are mainly supported by anchors on concrete slabs, so the loss of anchoring capacity may result in cabinet damage. Concrete materials are subject to various uncertainties and their variability exceeds that of other materials. As a result, using the finite element model of the electric cabinet-anchor system developed in previous studies, seismic fragility was evaluated in this study while accounting for the uncertainty of concrete materials. Thirty concrete material models were sampled using Latin hypercube sampling, and time history analysis was performed under artificial earthquake that satisfies the uniform hazard spectrum of the Uljin area. The stress of the anchor and the displacement of the top of the cabinet were defined as limit states. As a result, the damage begins when the anchor stress and top displacement exceeded 0.2 g and mostly fails at 0.5 g. In a future study, we plan to conduct a seismic fragility evaluation by considering the uncertainty of earthquakes and the uncertainty of materials simultaneously.

지진격리형 수배전반의 내진성능 평가

고동우 대한건축학회지회연합회 2019 대한건축학회연합논문집 Vol.21 No.1

In this study, a seismic capacity of isolated electrical cabinet system was evaluated through shaking table test. A high voltage Vacuum Contactor Breaker (VCB) was selected, and developed seismic isolation system, which is consisted of 4 damper and 10 scattered ball-caster, for electrical cabinet. Damper was to resist lateral force, and ball-casters absorbed vertical shock energy due to up-lift. Ground motion was adjusted to the spectrum defined from Korean seismic test method for telecommunication facilities. To evaluate seismic behavior of specimen, three dimensional accelerations were measured at three points of cabinet system. The dynamic amplification factors are ranged from 0.83 to 4.19, which is lower than that analysed in prior research. Because of the light weight of cabinet, overall behavior is governed by overturning and induced large up-lift behavior was monitored during the excitation. Maximum lateral drift of slender side of cabinet exceed 75mm which is allowed maximum lateral drift in KS standard, but large lateral drift is due to rocking behavior of cabinet. So, the cabinet can maintain its function after two times of excitation. 본 연구는 진동대실험을 통해 격리형수배전반의 내진성능을 평가하였다. 이를 위해 고압 VCB반을 선택하고 4개의 댐퍼와 10개의 분산 볼 캐스터로 구성된 지진 격리 시스템을 개발했다. 댐퍼는 횡방향에 대해 저항하며, 볼 캐스터는 상부 리프트로 인해 수직 충격 에너지를 흡수하게 된다. 지진동은 전기통신 시설의 지진 시험 방법에서 정의한 스펙트럼에 맞추었으며, VCB반의 지진 거동을 평가하기 위해 캐비닛 시스템의 세 지점에서 3차원 가속도를 측정했다. 동적 증폭 계수는 과거의 유사한 연구에서 보여준 증폭계수보다 낮은 0.83~4.19의 범위로 나타났다. VCB반 중량이 가볍기 때문에 실험과정에서 전도거동에 의한 들뜸이 크게 발생하였으며, 세장한 측의 횡방향 움직임도 KS규격에서 허용하는 최대 변형량 75mm를 초과하지만, 이와 같은 큰 움직임은 전도거동에 의한 들뜸에 의한 것으로 나타났다. 2회의 지진실험 후에도 VCB반이 작동하는데 이상이 없어 격리장치는 VCB반의 내진성능을 확보하는데 기여하였다.

A PROCEDURE FOR GENERATING IN-CABINET RESPONSE SPECTRA BASED ON STATE-SPACE MODEL IDENTIFICATION BY IMPACT TESTING

Cho, Sung-Gook,Cui, Jintao,Kim, Doo-Kie Korean Nuclear Society 2011 Nuclear Engineering and Technology Vol.43 No.6

The in-cabinet response spectrum is used to define the input motion in the seismic qualification of instruments and devices mounted inside an electrical cabinet. This paper presents a procedure for generating the in-cabinet response spectrum for electrical equipment based on in-situ testing by an impact hammer. The proposed procedure includes an algorithm to build the relationship between the impact forces and the measured acceleration responses of cabinet structures by estimating the state-space model. This model is used to predict seismic responses to the equivalent earthquake forces. Three types of structural model are analyzed for numerical verification of the proposed method. A comparison of predicted and simulated response spectra shows good convergence, demonstrating the potential of the proposed method to predict the response spectra for real cabinet structures using vibration tests. The presented procedure eliminates the uncertainty associated with constructing an analytical model of the electrical cabinet, which has complex mass distribution and stiffness.

A PROCEDURE FOR GENERATING IN-CABINET RESPONSE SPECTRA BASED ON STATE-SPACE MODEL IDENTIFICATION BY IMPACT TESTING

SUNG GOOK CHO,JINTAO CUI,김두기 한국원자력학회 2011 Nuclear Engineering and Technology Vol.43 No.6

The in-cabinet response spectrum is used to define the input motion in the seismic qualification of instruments and devices mounted inside an electrical cabinet. This paper presents a procedure for generating the in-cabinet response spectrum for electrical equipment based on in-situ testing by an impact hammer. The proposed procedure includes an algorithm to build the relationship between the impact forces and the measured acceleration responses of cabinet structures by estimating the state-space model. This model is used to predict seismic responses to the equivalent earthquake forces. Three types of structural model are analyzed for numerical verification of the proposed method. A comparison of predicted and simulated response spectra shows good convergence, demonstrating the potential of the proposed method to predict the response spectra for real cabinet structures using vibration tests. The presented procedure eliminates the uncertainty associated with constructing an analytical model of the electrical cabinet, which has complex mass distribution and stiffness.

전기 캐비닛-앵커 시스템의 지진 취약도 분석

손호영,정우영,전법규,주부석 한국복합신소재구조학회 2019 복합신소재구조학회논문집 Vol.10 No.6

The recent earthquakes in Gyeongju and Pohang have caused a lot of damage to structural elements as well as structural elements due to seismic waves that contain a lot of high frequency areas. Among the non-structural elements, the electrical cabinet keeps the power generation system controller of the plant, so that the damage in the electrical cabinet can be extended to secondary damage, such as the interruption of stable energy supply and the fire accident. In this study, the finite element model of electrical cabinet-anchor system is constructed and verified to apply input earthquake considering high frequency earthquake to perform seismic fragility analysis. For the finite element model of the electrical cabinet, the resonance frequency search result had a error of approximately 1% with the target frequency, and the finite element model of the post installed anchor showed a good match of the initial stiffness and maximum load point when compared with the experimental results. The time history analysis was performed by varying the scales to 0.2g, 0.5g, 0.8g, and 1.2g. Based on the analysis results, the seismic fragility assessment was performed, which is a probabilistic safety assessment. The analysis of time history of 0.2g scale showed that the stress generated by the anchors was the greatest at 280.15MPa and that they reacted sensitively to high frequency earthquakes. The slope changed rapidly between 0.2g and 0.5g when analyzing the seismic fragility with the stress of the anchors limited, and the displacement at the top of the cabinet was shown to be more sensitive to the displacement of the X-axis than the displacement of the Z-axis when analyzing the seismic fragility. 최근 발생한 경주 및 포항 지진은 고주파 영역의 성분이 많이 포함된 지진파로 구조적 요소 뿐만아니라 비구조적 요소에 피해가 많이 발생하였다. 비구조적 요소 중 전기 캐비닛은 발전소의 발전 시스템 컨트롤러를 보관하는 함으로써 전기 캐비닛의 피해는 안정적인 에너지 공급의 중단과 화재 등의 2차적인 피해로 확장될 수 있다. 따라서 본 연구에서는 전기 캐비닛- 앵커 시스템의 유한요소 모델을 구축하고 검증하여 세계 각지에서 발생한 지진파 적용을 통한 지진 취약도 평가를 수행하고자한다. 전기 캐비닛의 유한요소 모델의 경우 공진탐색 결과의 타겟 주파수와 약 1%의 오차가 발생하였으며 선설치 앵커의 유한요소 모델은 실험결과와 비교하였을 때 초기 강성 및 최대 하중점이 잘 일치하는 것으로 나타났다. 0.2g, 0.5g, 0.8g, 1.2g로 스케일을 변화시켜 시간이력해석을 수행하였으며 해석결과를 바탕으로 확률론적 안전성 평가인 지진 취약도 평가를 수행하였다. 0.2g 스케일의 시간이력 해석결과 경주 지진을 적용하였을 때 앵커에서 발생한 응력은 280.15MPa로 가장 크게 발생하였으며 고주파 지진에 민감하게 반응하는 것으로 나타났다. 앵커의 응력을 한계상태로 지진취약도 분석 시 0.2g와 0.5g 사이에서 기울기가 급격히 변하였으며 캐비닛 최상단의 변위를 한계상태로 지진 취약도 분석 시 Z축 변위 보다 X축 변위에 대해 민감하게 반응하는 것으로 나타났다.

지진하중 하에서 로킹모드에 의한 캐비닛의 응답특성 분석

임승현(Seung-Hyun Eem),전법규(Bub-Gyu Jeon),장성진(Sung-Jin Jang),최인길(In-Kil Choi) 한국소음진동공학회 2019 한국소음진동공학회 논문집 Vol.29 No.6

Safety-related electrical cabinets that are installed in nuclear power plants require seismic performance evaluation. The seismic performance evaluation for these cabinets is conducted by shaking table tests or numerical analyses. These methods usually assume that the electrical cabinets are rigidly anchored to the floor or foundation when performing the seismic evaluation by the numerical simulation. However, this assumption may not be valid depending on how the cabinets are anchored as rocking or uplifting could occur in a lower section of the cabinets that are anchored by anchored bolts. Researchers conducted a study to calculate these effects numerically. In their research, rocking, uplifting and shifting modes of the cabinets were determined by the shaking table test. In this study, the shaking table test was conducted to analyze the dynamic characteristics of the rocking mode of the cabinet.

Seismic behavior of simplified electrical cabinet model considering cast-in-place anchor in uncracked and cracked concretes

전법규,김성완,장성진,박동욱,이홍표 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.11

In the case of nuclear power plants near end of their design life, a reassessment of the performance of safetyrelated equipment may be necessary to determine whether to shut down or extend the operation of the power plant. Therefore, it is necessary to evaluate the level of performance decline due to degradation. Electrical cabinets, including MCC and switchgear, are representative safety-related equipment. Several studies have assessed the degradation and seismic performance of nuclear power plant equipment. Most of those researches are limited to individual components due to the size of safety-related equipment and test equipment. However, only a few studies assessed the degradation performance of electrical cabinets. The equipment of various nuclear power plants is anchored to concrete foundations, and crack in concrete foundations is one of the most representative of degradation that could be visually confirmed. However, it is difficult to find a study for analysis through testing the effect of cracks in concrete foundations on the response of electrical cabinet internal equipment fixed by anchors. In this study, using a simple cabinet model considering cast-in-place anchor in uncracked and cracked concretes, a tri-axial shaking table tests were performed and the seismic behavior were observed.

Seismic demand estimation of electrical cabinet in nuclear power plant considering equipment-anchor-interaction

조성국,Kashif Salman 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.4

This paper investigates the seismic behavior of an electrical cabinet considering the influence ofequipment-anchor-interaction (EAI) that is generally not taken into consideration in a decoupled analysis. The hysteresis behavior of an anchor bolt in concrete was thereby considered to highlight thisinteraction effect. To this end, the experimental behavior of an anchor bolt under reversed cyclic loadingwas taken from the recently developed literature, and a numerical model for the anchor hysteresis wasdeveloped using the component approach. The hysteresis properties were then used to calibrate themulti-linear link element that is implemented as a boundary condition for the cabinet incorporating theEAI. To highlight this EAI further, the nonlinear time history analysis was performed for a cabinetconsidering the hysteresis behavior comparative to a fixed boundary condition. Additionally, the influence on the seismic fragility was evaluated for the operational and structural condition of the cabinet. The numerical analysis considering the anchor hysteresis manifests that the in-cabinet response spectra(ICRS) are significantly amplified with the corresponding reduction in the seismic capacity of 25% and15% for an operational and structural safety condition under the selected protocols. Considering the fixedboundary condition over a realistic hysteresis behavior of the anchor bolt is more likely to overestimatethe seismic capacity of the cabinet in a seismic qualification procedure

수치해석 및 진동대 실험을 통한 충전기의 캐비닛내부응답스펙트럼(ICRS) 결과 비교

이상진,최인길,임승현,임승현 한국압력기기공학회 2019 한국압력기기공학회 논문집 Vol.15 No.1

The seismic capacity of electric cabinets in Nuclear Power Plants (NPPs) should be qualified before installation and be maintained during operation. However it can happen that identical devices cannnot be produced for replacement of devices mounted in electric cabinets. In case of when no In-Cabinet Response Spectrum (ICRS) is available for new devices, ICRS can be generated by using Finite Element Analysis (FEA). In this study we investigate structural response and ICRSs of battery charger which is supplied to NPPs. Test results on the battery charger are utilized in this study. The response is measured by accelerometers installed on the housing of the battery charger and local panels in the battery charger. Numerical analysis model is established based on resonant frequency search test results and validated by comparison with 2 types of earthquake testing results. ICRSs produced from the numerical model are compared with measured ICRSs in the seismic tests. Developed analysis model is a simple reduced model and anticipates ICRSs quite well as measured response in the tests overall despite of its structural limitation.