In the event of a fault current, milliohms can make the difference between a lineman going home for the day or being seriously injured or killed. With fault currents in the tens of thousands of amps or more, the parallel path to the lineman needs a resistance so low that milliohms do make a difference.
In Alaska, the 115-kV Quartz Creek transmission line connects two hydroelectric dams on the Kenai Peninsula with the ‘rail-belt’ — an area containing Alaska’s railroad, its most populous cities and about three-fourths of the state’s population. A ﬁfteen mile section of that line was rebuilt last November, in an area where snow storms regularly drop feet of snow throughout the winter.
All Hubbell Power Systems surge arresters are factory tested according to IEEE C62.11 and IEC 60099-4 routine test requirements. Once in use, surge arresters do not require field testing for routine maintenance. If arrester field testing is desired there are several test options with varying levels of usefulness and convenience.
The Versa-Tech® I and Versa-Tech® LT reclosers use a 2.4GHz remote radio to communicate over WiFi. Utilizing this option, there is no need for a local radio. The module is compatible with Versa-Tech I recloser running firmware versions 3.xx or 4.xx and with Versa-Tech LT recloser running firmware version 5.xx. The WiFi radio attaches in the same location as the Digi/XBee and SiFLEX radios and has the capability of communicating up to 100 feet from the recloser.
During the early development of the screw anchor, the load resistance of an installed anchor could not be predicted with adequate accuracy. Specific information on soil conditions was lacking, making anchor selection more or less a guess. With little consideration for soil variations, the effects of seasonal weather changes or drainage, soils were classified as: either sand, clay, hardpan or swamp. At that time, there was not a definitive explanation for the soil conditions.
When overhead electrical line workers employ proper personal protective grounding practices they are usually protected from electrical hazards that might arise from working on de-energized lines and equipment. But, what about workers at ground level? How are they protected, and from what kinds of situations are they protecting? The answer is from hazardous differences in step and touch potentials.
Topics: Lineman Grade Tools
It can be a challenge to identify the right elbow for varying applications. There are so many different points to consider when planning for your utility. Therefore, we put together seven simple questions to help in the process of picking the right elbow.
Topics: Cable Accessories
Elbow and parkingstand arresters are provided with a ground wire as well as a grounding eye for attaching a No.14 or equivalent drain wire. It is important to understand the correct way to install the drain wire, so that it does not negatively impact the performance of the arrester.
Topics: Cable Accessories
Pilot Protection Relaying uses a communications channel (pilot channel) to provide coordination between the line protection relays. The relaying system is an advanced alternative to Step Distance Relaying which requires no communication and therefore manual coordination between relays.
THE IMPORTANCE OF EQUIPMENT REPOSITIONING
In recent years, the U.S. has been faced with several different types of natural disasters from devastating floods, tornadoes and hurricanes to Super Storm Sandy. These disasters have made us rethink how to ensure the safety and reliability of our infrastructure and facilities.
Topics: equipment repositioning