Insulation Coordination

insulation coordination

[‚in·sə′lā·shən kō′ȯrd·ən‚ā·shən]
(electricity)
Steps taken to ensure that electric equipment is not damaged by overvoltages and that flashovers are localized in regions where no damage results from them.

Insulation Coordination

 

measures taken to coordi-nate the level of insulation in electrical equipment with the magnitudes of the overvoltages acting on it and the characteristics of the protection devices (protective gaps). The choice of an insulation level is a technical-economic problem: for each rated voltage of the electrical equipment there exists a technically achievable and economically most advantageous insulation level.

Before the advent of reliable arresters, insulation coordination was a method of grading insulation in which insulation breakdown’for example, in the equipment of an electric power substation’would be most probable at a place where the consequences of the breakdown are the least serious for service. Thus, the insulation of a power line is reduced as it approaches a substation, regarding the line as a unique arrester, and the strength of the internal insulation was made substantially greater than that of the external insulation: breakdowns of external insulation usually do not cause permanent damage. As methods of protection against overvoltages developed, the insulation level in electrical equipment came closer to the “natural level,” which for aerial power lines is defined as the breakdown voltage of the insulation under load and, for electrical machines and apparatus, as the rated service life of the insulation. Insulation chosen according to natural level must have a reliable system for protection from or limiting of overvoltages. Statistical methods, which were necessary because of the probabilistic nature of overvolt-ages, the process of aging of insulation, and other factors, came into general use in the 1960’s for solving the problems of the choice of insulation levels and the coordination of insulation.

D. V. RAZEVIG

References in periodicals archive ?
This is because the most of surge energy is deposited in arrester and suppressor, while energy let-through toward EUT is very low due to energy and insulation coordination of the selected arrester and suppressor.
Obtained results show that special attention should be given to selection of SPDs protection voltages in order to confirm their energy, as well as insulation coordination. This is very important for protection of equipment with capacitive load character, in which case values of maximal voltages higher than SPD' s protection voltages appears even for small cable lengths between SPD and equipment.
[4] Insulation coordination for equipment within low-voltage systems - Part 1: Principles, requirements and tests, IEC Std.
This paper presents some MATLAB-based applications, using its GUI facility, to prepare an interactive way of teaching the concepts of insulation coordination of substation.
Key Words: Insulation coordination, BSL, BIL, Substation shielding, MATLAB, Graphical user interface
Whether in transmission lines or substations, the task is, to keep a reasonable balance between the costs of insulation coordination and the desired risk of failure [1,2].
Due to the highly-cost apparatus, utilized in substations, insulation coordination of substations comprises a wide range of influential factors, including estimation of apparatus electrical strength, in terms of BIL (basic lightning impulse insulation level) and BSL (basic switching impulse insulation level), minimum required clearances, in which arcing is avoided, lightning arresters' rating, number and location, shielding against lightning strokes using overhead ground wires and masts, open breaker protection, influences of contamination and atmospher c conditions on insulation strength, etc.
Insulation coordination procedure is considered to be based on two different approaches; conventional and statistical.
Regarding the facts said above, the authors prepared some computer applications, used for teaching insulation coordination concepts, to make it easier whether for the instructors, teaching the subject or the students, deepening their understanding.
As said previously, insulation coordination of substations is comprised of different factors, while this paper has focused on four issues, which are phase-ground BSL, phase-phase BSL, estimating BIL via a simplified method and shielding of substations against lightning strokes.
3- Are you understanding the concept of insulation coordination better after using this utility
While there are new basic risks and requirements such as insulation coordination in the third edition of IEC 60601-1, risk management makes the application of the standard more flexible.