A Guide to Selection and Application
Surge protection has been a primary concern when connecting devices and equipment to low-, medium-, or high-voltage electrical systems. As the use of products and equipment with components and insulation systems vulnerable to voltage surges and spikes continues to increase, the requirement for surge arresters to protect against the effects due to lightning strikes, switching phenomenon, etc., continues to increase as well. From personal computers to HV transmission and distribution systems, everything is susceptible to these surges and their destructive effects. This subject is very broad with numerous conditions to address, such that it is possible to treat only the basic aspects of selection and application in a single article. Therefore, this article will concentrate on circuits/systems 1000V and greater and is intended to provide the reader with some general guidelines for the appropriate selection and application of lightning/surge arresters.
Selecting Current Transformers Part 1
As engineers, we are aware that electrical power systems have grown. How much have they grown? When was the last time you specified a 2400-volt system, a 4160-volt 250 MVA system, a 15 kV 500 MVA system or specified a 2000-amp 480-volt system? An industrial plant now requires a larger and more complex system than was required just a few years ago. The 2400-volt systems have all but disappeared; 4160-volt systems have expanded from 350 MVA to 63 kA (equivalent to 500 MVA). The 15 kV systems also have expanded to 63 kA (equivalent to 1500 MVA). Has all of the electrical system expanded?
Application Considerations for Series Combination
Overcurrent Protective Devices (OCPD) in New Installations
The application of Series Rated OCPD continues to be one of the most popular and, unfortunately, most abused methods of electrical project value engineering (VE). Proper due diligence must be performed by the parties applying series ratings. The latest version of applicable building codes should be referenced to ensure minimum safety standard compliance and to meet the Design Professional's electrical system performance criteria. It is a very common occurrence for series ratings to be specified by the design professional in multiple occupancy facilities such as: low-, medium- or high-rise condos, time shares, apartments, hotels or strip malls.
Design For Safety
Part 2 of our ongoing series focuses on giving tips and suggestions to the electrical design engineer to design electrical distribution systems with safety for the end user as the primary concern. Concern for worker safety continues to increase, and there are numerous items that can be specified and designs that can be implemented that will increase a worker's safety.
Internet-Accessible Power Monitoring & Control Systems
Accessing electrical system information from any location allows the system manager to provide quicker command and control of intelligent devices. At the dawn of these devices, the manager could only access system parameters at the distribution location. As data communication techniques evolved, devices could be monitored anywhere within the building or within closely knit campus settings through proprietary protocols. Now, the Internet allows real-time access anywhere on the globe through open protocols.