3 edition of IEEE guide for soil thermal resistivity measurements. found in the catalog.
IEEE guide for soil thermal resistivity measurements.
|Series||IEEE std -- 442-1981.|
|Contributions||IEEE Power Engineering Society. Insulated Conductors Committee., Institute of Electrical and Electronics Engineers.|
|The Physical Object|
|Pagination||16 p. :|
|Number of Pages||16|
We space conduits 2" apart. There was a paper published about 20 years ago on thermal conductivity by a fellow at SCE. The concrete should extend up at least a foot above the top duct so that if a backhoe operator should try to dig through he would have to take multiple bites to reach a duct. Microwave remote sensing from satellites has also proven useful as it has an advantage over TIR of not being effected by cloud cover.
Being copyright free, these numbers are widely copied, sometimes without acknowledgement. Photo shows, from left to right, models TP02, TP08, a ballpoint for purposes of size comparison, TP03 and TP09 The physical model behind this method is the infinite line source with constant power per unit length. The installation never had any trouble untill on dry year in August cable started poping. Unfortunately, this leads to overdesign the cable size - "just to be on a safe side" or cable fault when "rho" value is bigger than anticipated. Soil resistivity measurement is an important factor in finding the best location for any grounding system. By the time that I remove rocks from the trench and backfill, level and compact the bottom of the trench, and so forth I can stick in a conduit and be done with it.
Direct buried with low thermal resistivity medium is a lower cost option with superior performance in term of maximizing the cable ampacity. I cannot imagine having to test every single project, but if there are any important installations, especially high voltage and high amperage feeders, I would recommend a test or the concrete encased duct bank solution. The factors that influence the choice of instruments are discussed along with a presentation of fieldtechniques for various types of measurements. The soil resistivity can change dramatically with changes in moisture, temperature, and chemical content. Resources and Help The measurement of soil thermal stability, thermal resistivity, and underground cable ampacity Abstract: One of the most important factors affecting underground cable ampacity is the thermal resistivity of the soil.
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In single wire earth return power transmission systems, the earth itself is used as the path of conduction from the end customers the power consumers back to the transmission facility. RE: Buried Power Cables cuky Electrical 3 May 05 The requirement of soil thermal resistivity varies depending of the importance of the UG line, voltage, the amount of power to be delivered and live cycle cost of the installation.
RE: Buried Power Cables mc5w Electrical 4 May 05 For duct banks that more than 1 row of ducts I would use duct spacing of 10 or 12 inches, not 7.
Typically IEEE guide for soil thermal resistivity measurements. book worst likely scenario considered in the conventional underground design. Sunde developed a graphical method to interpret the test results.
Calculate the soil resistivity if the probe separation distance 1. Furthermore because of the very small measuring time 1 s there is no convection present in the measurements and only the thermal conductivity of the fluid is measured with very high accuracy.
There was a paper published about 20 years ago on thermal conductivity by a fellow at SCE. Furthermore a method is suggested for including this information in underground cable ampacity calculations.
The technique is based on recording the transient temperature rise of a thin vertical metal wire with infinite length when a step voltage is applied to it.
IEEE Std. The dual probe device is inserted into the soil and a heat pulse is applied and the temperature sensor records the response as a function of time.
The soil resistivity value is subject to great variation, due to moisture, temperature and chemical content. It consists of two parallel needle probes separated by a distance r. Thapar, V. Soil thermal properties are also becoming important in areas of environmental science such as determining water movement in radioactive waste and in locating buried land mines.
It helps you to shape up your technical skills in your everyday life as an electrical engineer. Abstract Revision Standard - Active. The paper offers a mathematical model for calculation of the soil thermal parameters, including the related standard deviations, using the least square method.
Both ends of the device were well insulated so all the heat essentially traveled out raidially through the soil. This makes the signal analysis straightforward steady state implies constant signals.
In general there is some value above which the impedance of the earth connection must not rise, and some maximum step voltage which must not be exceeded to avoid endangering people and livestock.
Remote sensing[ edit ] Remote sensing from satellites, aircraft has greatly enhanced how the variation in soil thermal properties can be identified and utilized to benefit many aspects of human endeavor. Using concrete and I like the 'red die' suggestion will at least increase the effective contact area with the native soil to a much larger area, aiding in heat dissipation.
A sample of unknown conductivity is placed between two samples of known conductivity usually brass plates. Instead, the signal is studied as a function of time. The corresponding values of the soil resistance were 35, 18, 13, Transient plane source method[ edit ] TPS sensor, model Hot Diskspiral radius about 15 mm Transient Plane Source Method, utilizing a plane sensor and a special mathematical model describing the heat conductivity, combined with electronics, enables the method to be used to measure Thermal Transport Properties.
Excavating contractors never ever see those things and keep right on digging. We space conduits 2" apart. This paper presents a method for measurements of soil thermal properties with a spherical probe along the cable installation routes. If you would like to discuss more you may contact Geotherm Inc www.
Utilities and TL owner often spec one soil sample location every ft or less at each depth the cable s.IEEE IEEE Guide for Soil Thermal Resistivity Measurements [IEEE] on sylvaindez.com *FREE* shipping on qualifying sylvaindez.com: IEEE. Get this from a library! IEEE Guide for Soil Thermal Resistivity Measurements.
IEEE GUIDE FOR THERMAL RESISTIVITY MEASUREMENTS OF SOILS AND BACKFILL MATERIALS. Contains the measurement of thermal resistivity of soil and backfill materials to include concrete, engineered backfills, grout, rock, sand, and any other material used to encase the cable system installed in the ground.
GUIDE FOR SOIL THERMAL. sylvaindez.com: IEEE IEEE Guide for Soil Thermal Resistivity Measurements () by IEEE and a great selection of similar New, Used and Collectible Books available now at great sylvaindez.com: Paperback.
May 05, · IEEE Std IEEE Guide for Soil Thermal Resistivity Measurement EPRI Report TR Soil Thermal Properties Manual for Underground Power Transmission: Soil Thermal Property Measurements, Soil Thermal Stability, and the Use of Corrective Thermal Backfills. IEEE Guide for Soil Thermal Resistivity Measurements A method for measurement of soil thermal resistivity that is based on the theory that the rate of temperature rise of a line heat source is dependent upon the thermal constants of the medium in which it is placed is given.