This blog is for people who want to get a very high-level concept and understanding of
"Electric Substation"
In this picture here that we see
this is a picture of a substation
So substations play a very very key ingredient and from afar
We've all gone down the road we've all seen
these complicated devices
that looks really odd as we're driving down the road
when we see a substation but they're actually pretty well designed
Electric substation have an upmost importance in electric distribution facility
converting AC voltages from one level to another level
or change the nature of supply meaning go from AC to DC
Now, AC to DC is very uncommon, right but it is gaining popularity
for the vast majority of electrical substation out there
it's converting from one voltage AC voltage to another AC voltage
Now, the general layout of a substation consists of conductors that run long the entire substation
and which is are really important whether they're interrupting fault interrupting switches
or load interrupting switches they play a very central role
Now, indoor substation these substations are divided into different compartments for controlling
and metering of devices there's a lot of complexities when you design a substation inside of a building
So not a lot of substations are designed that way albeit some certainly arc
Substations are further classified as Pole-Mounted Substations
Foundation Mounted Substation or Surface Mounted Substation
in terms of the required space indoor substations are less
right, so you have to make everything compact less space involved but that also comes
with a higher capital cost as you have to shrink everything
you also have to pay extra for that square footage
Outdoor substation much more required space because everything is spaced out
much easier to spot because it's everything is visible right
In the layout of a substation, we have these consider like the left part or part A
and the right part B, which is a exact replica of each other
So we'll focus on the left part and you can see
that it'll automatically get translated over to the right part
It's just a line that comes in like a cable that comes in and goes
and connects directly into the 12.47 kV bus
So it's connected to this bus right here and this bus
is nothing more than just a junction point a node essentially
and that connects other components on that same same node right
types of transformer depends on the location of the substation
As non-flammable, fluid insulated transformers, and sealed transformers
are suited for both indoor and outdoor use so those are typically only outdoor
The size of the transformer in terms of kVA should be capable of holding sudden overload
7kV to 480-volt dry type transformer are in the range of 750 to 250 kVA
So, for these 1240s these you know these voltages
these are very common for utility transformers that are serving 480-volt customers right
Formula below is used to evaluate the cost of a transformer based on
no load and full load losses, basically
you know the Capital Cost is equal to A times Po, and then you sum that with B which is the
per unit cost of the load losses and you multiply that with Pk which is the losses due to the load
Switchgear refers to the integrated collection of devices to control and iso-electrical equipment
through monitoring and protective equipment for power system protection
Switchgear is basically, within it allows you to take these voltages
and distribute them in a very compact space
These transformers are used to step down high values of current into low current ranges
which small size relay can easily bear to operate
In fact, normally the current on the secondary side of the CT, that is going into the relay
or the meter or other devices or either 5 AMP rated or 1 AMP rated
depending on the application
Now circuit breakers have the following ratings, there's a continuous current rating of the circuit breaker
and it must be higher than the maximum continuous current draw by the load
that is very important current continuously is drawn by the load
Asymmetrical is always higher than symmetrical fault current
Asymmetrical is higher because it also considers the X over R ratio
and that is only in play for a very very short period of time
High-Voltage Fuses, Fuses are generally applied for protecting
power transformers in a substance to provide interrupting of permanent fault
should be selected according to the following standard rating
and so, these are high voltage fuses for different types of applications
Now, and typically a disconnect switch is installed on both sides of a substation equipment
Like if you have a breaker, the switches are installed on the line side as well as the load side
and they're designed to carry load current continuously and
momentarily carry short circuit currents for a defined duration without any overheating
The relays are automatic protective switchgear mainly consists of relays and circuit breakers
So, these are devices that protect the generator or transmission lines or motors or
other heavy equipment like transformers and buses and that sort of thing
and different types of relays are you know there's a Differential relay,
there's Overcurrent relay, the Auto reclosing relay there's Ground relays
lots and lots of different types of relays
Surge arrester is really important for areas especially where there are lots of lightning
but typically surge arresters are very common in nearly all substation, outdoor substation applications,
These are the voltages that are used So, under System Voltage under 100 kV
Its minimum rated voltage should be above 0.8 times Um
So lack of protection of the equipment which is not with the most protection
or in closed vicinity of the arresters
Hello everyone, Abdul Rehman here from AllumiaX Engineering
To learn more and to continue sharpening your technical skills,
Please subscribe to this Youtube channel GeneralPAC by AllumiaX
or visit our website at allumiax.com/learn