Seasonal Influence on Safety of Substation Grounding
Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Computer Science Clay
Active In SP
**

Posts: 712
Joined: Jan 2009
#1
01-03-2009, 02:17 PM


Seasonal Influence on Safety of Substation Grounding


With the development of modern power system to the direction of extra-high voltage, large capacity, far distance transmission and application of advanced technologies the demand on the safety, stability and economic operation of power system became higher. A good grounding system is the fundamental insurance to keep the safe operation of the power system. The good grounding system should ensure the following:

" To provide safety to personnel during normal and fault conditions by limiting step and touch potential.
" To assure correct operation of electrical devices.
" To prevent damage to electrical apparatus.
" To dissipate lightning strokes.
" To stabilize voltage during transient conditions and therefore to minimize the probability of flashover during the transients

As it is stated in the ANSI/IEEE Standard 80-1986 "IEEE Guide for Safety in AC substation grounding," a safe grounding design has two objectives:

" To provide means to carry electric currents into the earth under normal and fault condition without exceeding any operational and equipment limit or adversely affecting continuity of service.
" To assure that a person in the vicinity of grounded facilities is not exposed to the danger of critical electrical shock.

A practical approach to safe grounding considers the interaction of two grounding systems: The intentional ground, consisting of ground electrodes buried at some depth below the earth surface, and the accidental ground, temporarily established by a person exposed to a potential gradient at a grounded facility.

An ideal ground should provide a near zero resistance to remote earth. In practice, the ground potential rise at the facility site increases proportionally to the fault current; the higher the current, the lower the value of total system resistance which must be obtained. For most large substations the ground resistance should be less than 1 Ohm. For smaller distribution substations the usually acceptable range is 1-5 Ohms, depending on the local conditions.
When a grounding system is designed, the fundamental method is to ensure the safety of human beings and power apparatus is to control the step and touch voltages in their respective safe region. step and touch voltage can be defined as follows.

Step Voltage
It is defined as the voltage between the feet of the person standing in near an energized object. It is equal to the difference in voltage given by the voltage distribution curve between two points at different distance from the electrode.

Touch Voltage
It is defined as the voltage between the energized object and the feet of the person in contact with the object. It is equal to the difference in voltage between the object and a point some distance away from it.
In different season, the resistivity of the surface soil layer would be changed. This would affect the safety of grounding systems. The value of step and touch voltage will move towards safe region or to the hazard side is the main concerned question
Use Search at http://topicideas.net/search.php wisely To Get Information About Project Topic and Seminar ideas with report/source code along pdf and ppt presenaion
Reply

Important Note..!

If you are not satisfied with above reply ,..Please

ASK HERE

So that we will collect data for you and will made reply to the request....OR try below "QUICK REPLY" box to add a reply to this page

Quick Reply
Message
Type your reply to this message here.


Image Verification
Please enter the text contained within the image into the text box below it. This process is used to prevent automated spam bots.
Image Verification
(case insensitive)

Possibly Related Threads...
Thread Author Replies Views Last Post
  active reflector for pedestrian safety jaseelati 0 134 13-01-2015, 01:35 PM
Last Post: jaseelati
  seminar report on gas insulated substation jaseelati 0 278 01-01-2015, 02:54 PM
Last Post: jaseelati
  Safety-Critical Systems Design pdf study tips 0 386 17-05-2013, 04:48 PM
Last Post: study tips
  Safety Car Parking study tips 0 341 14-02-2013, 02:29 PM
Last Post: study tips
  VEHICLE-TO-VEHICLE AND ROAD-SIDE SENSOR COMMUNICATION FOR ENHANCED ROAD SAFETY pdf project girl 0 357 24-01-2013, 01:00 PM
Last Post: project girl
  Safety assessment of routes in a regional network project girl 0 301 22-01-2013, 11:07 AM
Last Post: project girl
  Influence of channel width on n- and p-type nano-wire-MOSFETs on silicon project girl 0 388 21-01-2013, 12:02 PM
Last Post: project girl
  Vehicle Ad hoc NETworks & Vehicle Safety Communications project girl 0 343 01-01-2013, 12:59 PM
Last Post: project girl
  Commission Proposal on the General Safety of Motor Vehicles seminar tips 0 356 14-11-2012, 05:41 PM
Last Post: seminar tips
  Command for Dozing Remote Control System Enhances Operator Safety seminar flower 0 416 03-10-2012, 05:25 PM
Last Post: seminar flower