Most of us started our electrical careers with fairly good knowledge about the practical aspects of our jobs. We understood voltage, current, power, resistance, etc. We mastered the more esoteric areas such as electrical fields and stress control and only revisited these topics if our day-to-day job required it. Partial discharge (PD) is one of those areas where we might …
As time progresses and a cable system ages, the system’s bulk dielectric strength degrades. During this aging process, artifacts such as water trees, delamination, voids, and shield corrosion raise the local stress placed on the cable during normal operation. The exact way in which the strength of a device degrades depends upon many factors including voltage, thermal stresses, maintenance practices, …
Methods to check medium voltage cable integrity have evolved drastically in the last 30 to 40 years. The DC hipot test has largely been replaced by the 0.1 Hz very-low-frequency (VLF) test, and North American (IEEE) and European (IEC, CE, CIGRE) standards specify the VLF test method for solid dielectric medium-voltage cables. Throughout these years, the 0.1 Hz VLF test …
The behavioral components of incidents, injuries, and fatalities must be studied and understood to change the safety culture. This element of study has been missing from the data available to assist in improving workplace safety. Often, this type of information has never been compiled and reviewed. Figure 1 shows the relationship between incidents, injuries, and fatalities. As shown in Figure …
As energy storage systems (ESS) become more integrated into our society, the National Fire Protection Association (NFPA) provides resources to ensure they are installed safely and that our firefighters are prepared to respond to the safety issues they present. Even though batteries have been around for hundreds of years, new innovations allow us to do more with them than ever …
Not all equipment is created equal when it comes to production objectives versus safety objectives in an electrical power system. Certain devices should be tested and maintained to ensure uptime; others should be inspected to ensure they perform properly to protect workers in an arc flash event. When considering arc flash safety and selecting the associated PPE, the condition of …
Electrical workers, supervisors, and managers are instinctively aware that getting to the root cause of electrical incidents involving the safety of their people and/or the integrity of their equipment requires insightful questions. Failure to find the foundational root cause is a tragedy that compounds the incident itself. Unfortunately, if the first question asks, “Why did it happen?” the answer often …
To explain VLF tan delta, we must first explain the reason it was developed and how the concept and equipment used to perform this test came about. Tan delta is still a form of high-potential (hipot) testing but utilizes the advantages of both AC and DC testing while eliminating many, but not all, of the disadvantages. The very-low-frequency (VLF) portion …
While the chemistry behind dissolved gas analysis (DGA) is complex and important for industry chemists to understand, the typical DGA review need not be as complex. Thermal or hot metal gasses are commonly known in DGA, and they are widely understood by industry experts, chemists, and many asset owners. The carbon oxide gasses — carbon dioxide and carbon monoxide — …
Bushings are the means by which electric power passes to and from different electrical devices, as they provide a point of interface for electrical voltage to be applied and current to pass to and from an electrical apparatus. The bushing’s center conductor is above ground potential and must be electrically insulated from the tank walls, which are at ground potential. …