Aiming to stop wasteful use of energy and bridge the
power demand-supply gap, the Government of India enacted the Energy
Conservation Act(EC Act) and established Bureau of Energy Efficiency under
Ministry of Power. One of the important provisions of the EC Act relates to the
enforcement of Energy Conservation Building Codes for efficient use of energy
and its conservation in the buildings or building complexes.
As defined in the EC Act, “Energy Conservation Building Codes”
(ECBC) means the norms and standards of energy consumption expressed in terms
of per square metre of the area where the energy is used and includes the
location of the building.
The EC Act mandates the ECBC for buildings with a
connected load of 500 kW or contract demand of 600 kVA and above and are
intended to be used for the commercial purposes and are constructed after the
rules relating to ECBC have been notified by the States Governments under
section 15 (a).
The ECBC will set minimum energy efficiency standards for
design and construction of a nonresidential building. Energy performance
standards for the following building systems are included in the ECBC
•
Building
Envelope.
•
Lighting.
•
Heating
Ventilation and Air Conditioning.
•
Service
Water Heating.
•
Electric
Power and Distribution.
However,
the broad requirements of the Code with respect to the building envelope are
the same for new buildings as well as for extensions and modifications.
All over the world, ECBCs have a proven track record of significantly
reducing energy use in buildings in a highly cost effective way. The ECBC
benefit both individual building owners and the people and government at large.
Benefit to property owners include reduced energy costs and improved comfort
(both thermal and visual). The benefits to society include the following:
•
Reduced
capital investments in energy supply infrastructure.
•
Reduced
environmental impacts.
•
Improved
electricity reliability.
• More
efficient use of resource (It is cheaper to save energy than it is to build new
power plants).
It is estimated that
buildings that are ECBC compliant have a potential of savings to the tune of
about 30%-35%.
Road Map to make ECBC
Mandatory
Given the fact that the capacity in the country required
to effectively implement this code is inadequate, the implementation of the
codes will be on voluntary basis initially. Incentives to promote its use in
the voluntary phase will be provided. Only when there is sufficient
availability of both technical expertise and complaint material, will the codes
be made mandatory. The Government will launch an effective awareness campaign
to promote ECBC all over the country
All the buildings or
building complexes with a connected load of 500 kW or greater or a contract
demand of 600 kVA or greater* have to comply with the Code.
Buildings with 1,000 m2 or more of conditioned area are likely to
fall under the above load conditions. The following sections which deal with
mandatory and prescriptive requirements of new and existing buildings are
related to this specified threshold area. It is important to mention here that
these mandatory and prescriptive requirements are applicable only where the
building has a connected load of 500 kW or more or contract demand of 600 kVA
or more..
The Code is presently
under voluntary adoption in the country.
This Code would become mandatory as and when it is
notified by the Central and State government in the official Gazette under
clause (p) of §14 or clause (a) of §15 of the Energy Conservation Act 2001 (52
of
2001)
Basics of Transformers
Transformer is a static
device, which is used to either increase (Step up) or decrease (Step down) the
input supply voltage depending on the application and requirement. Transformers
consist of two or more coils that are electrically insulated, but magnetically
linked (see Figure 8.1). The primary coil connected to the power source and
secondary coil connects to the load.
Power transmitted from power
plants, is in the form of high-tension voltage (400 kV - 33 kV). The reasons
for transmitting HT voltage are:
•
Reduced
conductor size and investment on conductors
•
Reduced
the transmission losses and voltage drop.
At the user end, equipment
with various voltage rating is used for different applications. Hence, the
transmitted voltage is first stepped down (11 kV - 230V) through distribution
transformers and then the power supply is distributed to the various sections
and equipment. Distribution transformers are used normally in all commercial
buildings. They are kept energized around the clock providing power to the
building’s electrical equipment.
8.2.1.1
Maximum Allowable Power Transformer Losses
Transformers are of two types - Dry type and Oil
filled. Fire safety and environmental concerns associated with transformers are
important. There is a misconception that oil filled transformers are not
installed at fire hazardous places. It all depends on the Thermal Capacity and
Ignition temperature of the insulating materials used. If the thermal capacity
of the oil used is higher than the insulating materials used in the Dry type transformers
then they are more hazardous as compared to oil filled transformers.
Distribution transformers consume energy even when the
building is not occupied or its equipment are not operating, resulting in
energy loss.
Transformers losses are discussed in Box 8-A.
The efficiency of
transformers normally varies anywhere between 96 to 99 percent.The efficiency
not only depends on the design, but also, on the effective operating load.
Transformer losses consist of two parts: No-load Loss and Load Loss
No-load Loss (also called core loss) is the power consumed to
sustain the magnetic field in the transformer's steel core. Core loss
occurs whenever the transformer is energized; and it does not vary with load.
Core losses are caused by two factors: hysteresis and eddy current losses.
Hysteresis loss is that energy loss caused by reversing of the magnetic field
in the core as the magnetizing alternating current rises and falls and reverses
direction. Eddy current loss is a result of induced currents circulating in the
core.
Load Loss (also called copper loss) is associated with full-load current flow
in the transformer windings.
Copper loss is power lost in
the primary and secondary windings of a transformer due to the ohmic resistance
of the windings. Copper loss varies with the square of the load current. (P=I2R).
Transformer
losses as a percentage of load is given in the Figure 8.2.
For a given transformer, the
manufacturer can supply values for no-load loss, PNo-load, and load
loss, PLoad. The total transformer loss, PTotal, at any
load level can then be calculated from:
PTotal
= PNo-load+ (% Load/100)2 × PLoad
Source: Energy Efficiency in Electrical Utilities,
Bureau of Energy Efficiency, 2005.
As per the Code:
Power transformers of the proper ratings and design must be selected to
satisfy the minimum acceptable efficiency at 50% and full load rating. In
addition, the transformer must be selected such that it minimizes the total of
its initial cost in addition to the present value of the cost of its total lost
energy while serving its estimated loads during its respective life span.
ECBC
lists various transformer sizes of dry-type and oil-filled transformers and
their associated losses at 50% and full load rating
(Table 8.1 and Table 8.2 of
ECBC).
Total loss value given in the above table are applicable for thermal classes E,B and F and have component of load loss at refrence.
Temperature according to clause 17 of IS 2026:Part 11 i.e, average winding temperature rise as given in coloumn 2 of Table 8.2 Plus.
30°C. An increase of 7% on total for thermal class H is allowed.
Total loss value given in the above table are applicable for tharmal classes E,B and F and have component of load loss at refrence.
Temperature according to clause 17 of IS 2026:Part 11 i.e, average winding temperature rise as given in coloumn 2 of Table 8.2 Plus.
30°C.
An increase of 7% on total for thermal class H is allowed.
CALCULATIONS DEPICTING THE PAYBACK PERIOD:
Return On Investment (ROI) for Transformer Of 1500KVA
with 100% Loading.
From above
it can be concluded that we can approx. Rs. 3.25Lac on our electricity bill and
additional cost price paid by us shall be returnable after 18Months, this is
will be a huge saving on the electricity bills.
For More info@saielectricals.com
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