Unit 1: Overview
of substations Electrical Substation
and Practices Notes - Mypractically
Substation
Question- Define substation.
Answer-
Substation- An assembly of apparatus used to change some characteristics such as voltage, frequency and power factor of electric supply is called a substation.
Following are the important points (Significance) about substation
<![if !supportLists]>1. <![endif]>It should
be located at a proper
site
<![if !supportLists]>2. <![endif]>It should
be located at the centre
of gravity of load
<![if !supportLists]>3. <![endif]>It should
provide safe and reliable arrangement
<![if !supportLists]>4. <![endif]>It should
be easily operated
and maintained
<![if !supportLists]>5. <![endif]>It should
involve minimum capital
cost
Need of electrical substation
Question- State the need of electrical substation
Question- State the importance of electrical substation
Answer- Electrical substation is needed because of the following reasons
<![if !supportLists]>1. <![endif]>Substation is the most important part of electrical power system. It helps
in maintaining the continuity of electric supply.
<![if !supportLists]>2. <![endif]>During operation
of transmission and distribution of electric network,
it is necessary and desirable to change some electrical
characteristics such as voltage, frequency and power factor. This is possible
with the help of substation
<![if !supportLists]>3. <![endif]>Similarly,
near the end of consumer, the voltage may have to be stepped down to utility
level. This is possible using assembly of apparatus called as substation.
<![if !supportLists]>4. <![endif]>In some
cases, in the line of the power system, it may be desirable to convert the large magnitude ac power into dc power such as electric traction
and electroplating. This can be done by using substation.
<![if !supportLists]>5. <![endif]>To satisfy
the load demand
<![if !supportLists]>6. <![endif]>To accommodate new power generation
<![if !supportLists]>7. <![endif]>To maintain
the reliability of the power system
<![if !supportLists]>8. <![endif]>To step up or step down AC voltage
using transformer
<![if !supportLists]>9. <![endif]>To break
the power flow
<![if !supportLists]>10. <![endif]>To interconnect the two different
transmission voltages
Factors governing the selection of the site of the
substation Question-
State the factors
governing the site selection of substation Following
factors are consider while designing a substation
<![if !supportLists]>1. <![endif]>Type of Substation:
The category of substation is important for its location. For example a step-up substation, which is generally a point where power from various sources (generating machines or generating stations) is pooled and stepped up for long distance transmission, should be located as close to the generating stations as possible to minimize the transmission losses.
Similarly a step-down substation should be located nearer to the load centre to reduce transmission losses, cost of distribution system and better reliability of supply.
<![if !supportLists]>2. <![endif]>Availability of Suitable and Sufficient Land:
The land proposed for a substation should be normally level and open from all sides. It should not be water logged particularly in rainy season. The site selected for a substation should be such that approach of transmission lines and their take off can be easily possible without any obstruction.
According to the latest practice the land required for various types of substations is given below:
Type of substation Area required
<![if !supportLists]>·
<![endif]>400 kV Substation 50 acres
<![if !supportLists]>·
<![endif]>220 kV Substation 25 acres
<![if !supportLists]>·
<![endif]>132 kV Substation 10 acres
The places nearer to aerodrome, shooting practice grounds etc., should be avoided.
<![if !supportLists]>3. <![endif]>Communication Facility:
Suitable communication facility is desirable at a proposed substation both during and after its construction. It is better, therefore, to select the site along-side on existing road to facilitate an easier and cheaper transportation.
<![if !supportLists]>4. <![endif]>Atmospheric Pollution:
Atmosphere around factories, which may produce metal corroding gases, air fumes, conductive dust etc., and nearer to sea coasts, where air may be more humid and may be salt laden, is detrimental to the proper running of power system and therefore substations should not be located near factories or sea coast.
<![if !supportLists]>5. <![endif]>Availability of Essential Amenities to the Staff:
The site should be such where staff can be provided essential amenities like school, hospital, drinking water, housing etc.
<![if !supportLists]>6. <![endif]>Drainage Facility:
The site selected for the proposed substation should have proper drainage arrangement or possibility of making effective drainage arrangement to avoid pollution of air and growth of micro-organisms detrimental to equipment and health.
<![if !supportLists]>7. <![endif]>Transportation facility:
The substation consists of major equipment’s such as transformer, isolator, and circuit breaker; the site selected for the substation should be located such that the transportation facilities are easily available. Transportation facilities are required to transfer the material, machineries and labours during installation, loading, unloading and maintenance.
Conclusion:- Thus, from this post we understood the Need of Substation and Factors Affecting or Site Selection of Substation.