Machine learning-based approaches for fault diagnosis on transmission lines have attracted increasing attention in recent years, yet concerns over their robustness and explainability hamper their practical applications. Moreover, separate algorithms are normally used to solve the fault classification and location tasks. In this work, we focus on these tasks and propose an integrated model based on Convolutional Neural Network, whose improved performance over separate models is demonstrated by numerical results. Besides, explainability of the proposed model is demonstrated and analyzed. Specifically, the class activation maps and attention maps illustrate that the proposed structure can reduce the degradation of model performance due to data pollution, enhancing the credibility of the proposed method in practical applications. Moreover, the proposed model outperforms existing machine learning-based models in terms of accuracy and robustness. Such a structure has been proven effective on field data and can be applied to many other tasks of fault diagnosis.