E3-E4 ELECTRICAL
(Technical)
EMERGING TRENDS IN SUB- STATION
6/10/2011
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WELCOME
• This is a presentation for the E3-E4 Electrical
( Technical) Module for the Topic: EMERGING
TRENDS IN SUB-STATION
• Eligibility: Those who have got the Upgradation
from E3 to E4.
• This presentation is last updated on 10-6-2011.
• You can also visit the Digital library of BSNL to see
this topic.
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AGENDA
Concept of Unitized Sub- station (USS)
Salient Features and
Advantages of USS
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• A substation is a part of an electrical generation,
transmission, and distribution system.
• Substations transform voltage from high to low, or the
reverse, or perform any of several other important
functions. Electric power may flow through several
substations between generating plant and consumer,
and its voltage may change in several steps.
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• A substation that has a step-up transformer increases
the voltage while decreasing the Current, while a stepdown transformer decreases the voltage while increasing
the current for domestic and commercial distribution.
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Disadvantages of Pole Mounted T/F Sub-station
•
•
•
•
Transformers sub –station using pole structures are
widely used, where the basic disadvantages of the
system are:
Ugly structures,
Large utilization of space,
Improper fuse links resulting in no proper protection to
transformers.
When faults take place, heavy damage to transformers
and auxiliary systems are reported. Instead of using
proper rating of fuses, people have been using wires,
which is technically incorrect. Recent development in this
field is the Unitized Sub station.
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UNITISED SUB-STATION
• The unitized substation is a state-of-the-art-system
which simplifies conventional substation design. USS is
fully engineered factory built design, tailor made to
customer needs.
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UNITISED SUB-STATION
• USS comprises of a single substation, factory built
package having transformer, HT and LT controls.
• The safety features and mandatory requirements are
fully complied with.
• USS is a fit and forget technology,
• The connections are precise, secure and totally
enclosed. Hence no chance for failure, corrosion and
losses.
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Unitised Sub-Station (Contd.)
•
USS is built as a product considering the aesthetics,
safety and ease of installation.
• Due to the enclosed construction :
• It avoids bird hit.
• Human/animal contacts which may lead to fatal
accidents ,disruption of supply and power loss as may
happen in the open execution.
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Unitised Sub-Station (Contd.)
• In open execution installations, the AB switch /
Transformer / LA are mounted either on two or four pole
structures. The hanging and sagging of the wires give a
clumsy appearance, affecting the elevation of the
building. Moreover, the tall structures not only occupy
the floor area, but also the shaft area along the high rise
building
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Space Saving & Cost Effective
• Space to install USS is typically 10’ X 10’ which is
approximately the space required for a car park.
• Saving of floor space to the tune of 80-85% can be
achieved by installing USS as compared to that required
for conventional installation.
• Advisable to opt for HT supply in places where the
consumption is around 125 KVA. The additional cost of
installation can be recovered in few years.
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Salient Features
• Design conforms to lEC 62271-202 standards
• The compartmentalized construction prevents accidental
entry to energized areas
• Meets IP53/IP23 degree of protection
• Tailored configuration to customer needs
• Designed to withstand electrical impulses, thermal and
dynamic stresses
• Variety and choices for MV/LV switchgear
• Low power loss and low noise transformer
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Salient Features (Contd.)
• Number of feeders for LV can be customer specific
• Easy to install
• Delivery ready for commissioning
• Modern
manufacturing
effectiveness,
reliability
techniques
ensure
cost
and
trouble
free
long
performance
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Applications
• Can be placed in the basement or ground floor or on roof
top of the high rise building.
• USS enclosure design helps in venting out the heat
generated in the transformer cubicle.
• In Indoor USS located at the basement of high-rise
buildings, natural ventilation is more than adequate for
cooling. However, in places where natural cooling is
insufficient, forced cooling with fans can be provided on .
• USS can also be installed at construction sites,
exhibitions, open cast mines as mobile substation, either
on truck or skid mounted.
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Metering
• EB metering (Optional)
• USS can be offered with Tariff (TOD) meter. The CTs &
PTs for TOD (Time of Day) meter are housed in a
separate cubicle with tamper proof sealing arrangement.
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Indications
• Dynamic Mimic
• The status (ON & OFF) of both main & earth switch will
be automatically indicated in the mimic diagram for triple
pole gang operated load break switch. Also healthiness
of the fuses, spring charge indication are provided
separately.
• Live Line Indicator
• Specially designed live line indicators operating through
Voltage Sensors for indication if the cable terminals are
live or not.
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Protection
• Over Current & Earth Fault Protection
• Unique O/C & E/F protection for Transformers controlled
by Load Break Switch Fuse Unit.
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Transformer Compartment
• The
compact
substation
incorporates
Distribution
Transformer which is designed and made strictly as per
IEC 60076 and IS 2026 specifications.
• The transformer compartment is fitted with removable
bolted cover with louvers and sand traps.
• This design allows maximum ventilation and prevents
ingress of sand or its accumulation in door cavities.
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HV Compartment
• It comes in two versions
• Vacuum Circuit Breaker RMU &
•
H V Fuse RMU and load break switch
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LV Compartment
• The LV Distribution Board is connected to LV bushing of
the transformer.
• The LVDB can be designed to meet various application
and requirements having
• MCCBs and ACB
• LV fuse switch units
• Instrumentation and metering
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Interconnections
• Connection Between Compartments
• Specially designed Elasta mould HV bushings is
provided for complete safety of equipments.
• The connection between the transformer and the RMU is
made with XLPE insulated cable.
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Advantages of Unitized Package Substation
• Custom built design and suitable for constant mobility. This
provides a high flexible power supply points without much
difficulties.
• Reduced Electrical losses as package substation can be
provided in the center location of load.
• Total economy in cost. Even site cable cost is minimized as
the transformer is directly connected to LV switch board.
• High degree of safety and operational reliability is achieved by
HT and LT switchgears and protective relays to avoid
overloading
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Advantages of Unitized Package Substation (Contd.)
• Reduced fire risk by eliminating oil-filled transformers
and ensures safety when installed in chemically
hazardous places like petrochemical complexes, drilling
platforms, etc.
• Light Weight Unitized Package Substation is made from
high grade raw material.
• Light Weight Unitized Package Substation reduces
electrical losses in cable runs especially LV side, since
these packages substations can be located exactly at
the load centre.
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Advantages of Unitized Package Substation (contd.)
• Simplified contractual procedures by single sourcing of
complete substations.
• Reduced weight compared with other designs of
equipment performing the same function.
• Because these are fully factory assembled units,
mounting on the site-prepared foundation is easy
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