The pole is usually treated from the butt to about 2 ft above the ground line. Treated fir has also been supplied in some quantity from the Northwest.Ĭedar poles resist decay, but satisfactory life is not secured unless the butt is treated. It is logical that the reasons for choosing the more expensive steel construction should require conservative design throughout and that conditions justifying the cheaper and shorter-lived wood structures would warrant accepting some of the more theoretical hazards.įor voltages of 69 kV and lower, wood is quite generally used. Wood-pole construction for many years has been used for all voltages up to and including 345 kV. H frames with various modifications have been designed, the most popular using the main crossarm as the bottom member of a truss.īutt-treated cedar and full-treated pine are used almost exclusively in transmission-line construction the use of untreated poles has been practically abandoned as uneconomical since the supply of chestnut and northern cedar poles has been exhausted. Generally, steel structures are designed to support safely one or more broken conductors, whereas wood structures are often not so designed.
The lower cost is due, in part, to the more conservative basis of design normally adopted for steel. The results show the robustness of the proposed approach.Wood poles are considerably cheaper than steel for many types of construction. It allows replacement of bad data with almost exact values. Moreover, to eliminate the bad data, sensitivity based bad data elimination approach is presented. The performance of the proposed estimator is validated on the sag and tension data obtained with simulations on PLS-CADD™. Though, designed assuming ideal leveled span configuration, it is found to work for actual operating conditions. The estimator uses the conductor temperature and tension at one end of the span as input. Using this, a reduced order, least-square based state estimator is proposed to estimate the sag in leveled span configuration. To reduce the number of sensors and identify their location a linear integer programming based optimal sensor placement approach is proposed while keeping the redundancy intact. This paper attempts to reduce the sensor requirement and estimate the sag in leveled span. PMS requires sensors on every tower as a result, sensor and data transmission requirements are high. But, due to the limitation of DMS to use ruling span method, PMS is preferred.
To monitor sag, distributed (DMS) or point measurement systems (PMS) are used.
However, remote locations of the conductor limit observability of sag. Mechanical sag of the overhead transmission line (OTL) is a critical parameter for power system operation.
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