Electrical Life Test Research Articles

Electrical Life Test of Small Shell Type Special Contactor and Analysis of Change Trend of Key Characteristics

In dealing with electrical fire cases, it is necessary to trace the quality of various electrical products running on the line. It is a very effective and direct way to test the electrical life of the samples of the same specifications and models. The research of electrical life test characteristics can reflect the structural problems, movement performance and other characteristics of the product, which provides a basis for understanding the working state of the product and analyzing the failure reasons. In this paper, a kind of small shell type special contactor commonly used in low-voltage distribution system is taken as the research object, and the variation trend of characteristic parameters such as arcing time, arcing energy and opening phase angle with the operation times of electrical life test is analyzed. Through the establishment of key characteristic quantity database of electrical life, we can better analyze the product performance and grasp the operation status, and provide strong data support for the traceability work caused by its quality problems in electrical fire cases.

Research on electrical life Trace prediction of contact based on SG-BP algorithm

In order to prevent electrical fire in low-voltage distribution system, it is a very effective measure to predict the electrical life of various low-voltage electrical appliances running on the line. At present, it is difficult to predict the residual electrical life of AC contactors. How to establish a reasonable and reliable prediction model for the residual electrical life of AC contactors is the key to the electrical life test and characteristic research of AC contactors. In this paper, Savitzky-Golay convolution smoothing algorithm is combined with BP neural network algorithm, and the remaining electrical life prediction model of contact is established by taking the arcing time, arcing energy and contact opening phase angle as the input parameters of the prediction model. The test results show that the average relative error of BP residual electrical life prediction model is less than 4%, and the maximum relative error is less than 10%. Combined with Savitzky-Golay convolution smoothing algorithm, SG-BP residual electrical life prediction model has average relative error less than 3% and maximum relative error less than 8%, which improves the prediction accuracy of residual electrical life, and lays a good foundation for making safe and reliable judgment by making better use of electrical life trace data..

Electrical Performance Degradation Model and Residual Electrical Life Prediction for AC Contactor

The electrical performance of ac contactor degrades under electric load stress, and the degradation data contains the information concerning the residual electrical life (REL). This article proposes an online reliability evaluation method that relates contact erosion loss (CEL) to electric load stress, performance degradation process, and electrical life prediction. First, the degradation variable of normal distribution is constructed by segmenting accumulation of CEL, and a degradation model based on Wiener process is established. With the knowledge of the first accumulation of CEL beyond failure threshold, the probability density function (PDF) of REL for ac contactor is presented, and the point estimation value and an interval estimation value of REL are calculated. Second, a simulation electrical life test is conducted using Monte Carlo method, and results show that the electrical performance degradation model and the prediction method of REL raised in this article are effective. Finally, CELs weighed in the electrical life test are applied in the prediction process of REL of ac contactor and the prediction error is proven acceptable in practical application. Compared with the neural network-based methods, the proposed method provides an intuitive and simple mathematical model with clear physical interpretations.

Method of selecting step stress test parameters for XLPE insulation DC voltage endurance coefficient

Cross-linked polyethylene (XLPE) insulation DC voltage endurance coefficient (VEC) is an important basis in the selection of DC cable insulation design and factory test parameters. Studies on the degradation of XLPE insulation performance under DC electric field can also provide technical support for the reliability evaluation of cable operation. The step stress method as an efficient electrical life test method is widely used to obtain VEC. The parameters of step stress method present considerable influences on VEC. An analytical method based on the trajectory of the damage curve and equivalence between step stress test and constant stress test within zone division is proposed in this paper. According to the proposed method, several sets of step stress tests with different test parameters have been carried out. The accuracy of the test results has been confirmed via analyzing test data. The experimental results show that the VEC (n=12.0) obtained by the step stress test whose parameters are selected by proposed method has good equivalence with the result (n=12.2) under constant-stress method.

Analysis of Electrical Life Distribution Characteristics of AC Contactor Based on Performance Degradation

Electrical life is an important performance indicator of ac contactor, and it is influenced by various factors, among which the most important one is arc erosion caused by arc current. This paper proposes a general contact erosion model based on arcing phase angle to simulate the electrical life distribution characteristics of ac contactor under random breaking operations. For the same type of ac contactor, different individuals have different electrical life due to the manufacturing dispersion, so the normal distribution is utilized to simulate the manufacturing dispersion under $3\sigma $ standard. The simulation results show that the electrical life distribution is closely related to the manufacturing dispersion degree. When the dispersion degree of manufacturing processes is relatively low, the electrical life obeys three-parameter Weibull distribution. Otherwise, the electrical life of contactors obeys normal distribution. Finally, the electrical life test is performed, and the test results are consistent with the theoretical analysis results. The abovementioned conclusion provides theoretical foundation for the reliability evaluation and experimental study of ac contactor.

Inference life-models of electrical insulating materials by using a Kalman filter

A Kalman filter is applied to life tests for characterizing electrical or thermal endurance of electrical insulating materials. This recursive estimator provides updated life model parameter values after each life test. The life models are: (1) inverse power law and the exponential law, used for electrical or multi-stress ageing; and (2) Arrhenius model, used for thermal ageing. The state, prediction, and updating equations of the Kalman filter algorithm are specified for insulation endurance inference. Insight into the definition of the state variables, which are directly related to the model parameters, and determination of system and observation errors are developed. A recursive breakdown test detects important changes in the prevailing ageing process. The range of validity of the life model, as well as information on electrical and thermal threshold are considered. A flow chart of the filtering algorithm is presented. Example experimental results relevant to insulating materials and systems subjected to electrical and thermal life tests are processed according to the algorithm. >

Erosion Characteristics of Silver-Based Contact Materials In a DC Contactor

Electrical life tests in a dc contactor are performed under DC4 and DC5 conditions. Results from our observations and erosion measurements are compared for different silver-based contact materials. For the device used a relation can be established between the arc energy and material loss and transfer. The erosion mechanism during the make operation determines the overall arc erosion to a larger than expected extent. Silver nickel 90/10 stands out as the contact material with the lowest erosion rate under both conditions.