Abstract Surge arresters are at the forefront of protection against voltage surges. The loss of the protective effect of surge arresters imposes accidents and unplanned shutdowns on the power system. It directly affects the interruption of power supplies and imposes fines on service providers. Monitoring and diagnostics in the lightning rod field require studies and work that present the degradation behaviour of surge arresters to help develop and improve existing techniques. This paper presents the development of a laboratory with a low-energy, mobile current waveform impulse generator. It allows for conducting aging tests by applying discharges to low-voltage zinc oxide surge arresters used in the energy distribution sector. Samples of surge arresters were subjected to the discharges produced by the developed generator, and they exhibited degradation, thus showing asymmetry between the positive and negative half-cycles of leakage current.

Abstract As high-voltage circuit breakers (HVCBs) are responsible for switching off the load in the event of anomalies, they suffer various wear and tear, both on their main contacts and on the other actuation mechanisms. Not only load maneuvers but also weather conditions can bring factors that contribute to deterioration and, consequently, contribute to failures of this component that is so important for energy supply. Both failures and maintenance shutdowns generate costs for substations, something that could be minimized if there was monitoring of the condition of the HVCBs. This paper shows a methodology to analyze the vibration signal of HVCB in order to identify and quantify contact failures. The proposed methodology is verified through an experimental setup. The results show that it is possible not only to identify the fault but also to assess its intensity using vibration analysis.

Abstract The continuity of an electrical system's services is linked to its equipment's correct operation. The more correctly they worked, the higher the quality of the services provided. Thus, they must have their functioning scanned closely and that minor defects have their evolution monitored. This fact creates the possibility of making predictions about how long equipment can operate without compromising the system's continuity. This follow-up is proper for predictive maintenance. This paper presents three on-going COPEL Generation and Transmission projects in essential elements of its electrical system: circuit breakers, lightning arresters, and SF6 substation. The central idea of all monitoring projects is to check the early problem in this equipment and facilities.

ABSTRACT The current pricing process of raw milk in Brazil discourages producers from improving milk composition, which affects both yield and quality of dairy products. Furthermore, small and medium-sized dairies face great difficulties when it comes to planning production. Thus, a linear programming model was developed to price the raw milk and determine the optimal mix (combination of quantities) of dairy products that maximizes total contribution margin (TCM) under daily scenarios of high (January) and low (July) raw milk supplies (summer and winter, respectively) by comparing optimal solutions with actual results. The TCM of optimal and actual mixes were higher in January due to the greater availability of raw material. Packaging was a limiting factor in the production of cheese in optimal mixes. The relationship between unit contribution margin (UCM) and the required amount of raw materials per product unit and resource availability is crucial to defining the mix of dairy products and TCM of the dairy. Casein and raw milk volume showed shadow prices. Under both scenarios, the calculated prices of raw milk were higher than the prices charged by the dairy and were higher in January. The proposed model remunerates the producers based on the quantity and quality of raw milk. The dairy can maximize its TCM by better planning its mix of products with the use of linear programming.