Electricity
distribution in Pakistan faces number of challenges, including voltage
fluctuations, load variations and power quality issues. One effective solution
to address these challenges is the installation of Automatic Voltage Regulators
(AVRs) on distribution feeders. In this article, we will discuss the selection
and installation of 11kV AVRs on 11kV electricity distribution feeders in
Pakistan.
Selection
of 11kV AVRs:
Selecting
the right AVR for a distribution feeder requires careful consideration of
various factors. Firstly, the capacity of the AVR should be chosen based on the
maximum load demand of the distribution feeder. The AVR should have sufficient
capacity to regulate the voltage within the desired range, considering both
normal and peak load conditions.
Secondly,
the type of AVR should be chosen based on the specific requirements of the
distribution feeder. Common types of AVRs used in Pakistan include
tap-changer-based AVRs, step-voltage regulators, and electronic voltage
regulators. Each type has its advantages and disadvantages in terms of
performance, cost, and maintenance requirements.
Furthermore,
the reliability, durability, and performance history of the AVR brand and model
should be thoroughly evaluated. It's important to choose AVRs from reputable
manufacturers with a proven track record in the industry. Additionally, the
availability of spare parts, technical support, and after-sales services should
be considered for long-term maintenance and operation.
Installation
of 11kV AVRs:
The
installation of 11kV AVRs should be carried out by qualified and experienced
electrical engineers following relevant safety and regulatory standards. The
location for AVR installation should be carefully selected to ensure
accessibility, safety, and protection from environmental factors. The AVR
should be installed in a suitable weatherproof enclosure with proper
ventilation and cooling arrangements.
The
electrical connections of the AVR, including input and output connections,
should be made as per the manufacturer's guidelines and the distribution
feeder's requirements. Adequate protection devices, such as circuit breakers or
load break switch, surge protectors, and earthing arrangements should be
installed to safeguard the AVR and the distribution feeder from electrical
faults and transients.
Once
the AVR is installed, it should be commissioned and tested to ensure proper
functioning on no load. The AVR settings, such as voltage set points,
regulation range, and response time, should be configured as per the
distribution feeder's requirements. Regular maintenance, including periodic
inspection, cleaning, and calibration, should be carried out to ensure optimal
performance and longevity of the AVR.
Periodic Maintenance
Below mentioned maintenance schedule is a general guideline and should be customized based on the manufacturer's recommendations, specific site conditions, and operational requirements. Follow the manufacturer's instructions, guidelines, and safety protocols for proper maintenance of the AVR, and involve qualified person and experienced electrical engineers for any maintenance activities.
i. Inspect the AVR enclosure for any signs of physical damage or corrosion.
ii.
Verify
the AVR input and output connections for tightness and proper alignment.
iii.
Monitor
the AVR's operating parameters, including voltage set points, regulation range,
and response time, and make adjustments as needed.
iv.
Inspect
the protection devices, such as circuit breakers / load break switch and surge
protectors, for proper functioning and reset any tripped breakers or
protectors.
v.
Verify
the grounding arrangements and ensure proper grounding of the AVR.
vi.
Check
and record the operating hours of the AVR to schedule maintenance and
replacements as per the manufacturer's recommendations.
vii.
Inspect
and clean the AVR's external cooling fans, if applicable, and replace if
necessary.
viii.
Conduct
a detailed inspection and cleaning of the AVR's tap changer, including
contacts, insulation, and oil quality, and perform any required maintenance or
replacements as per the manufacturer's recommendations.
ix.
Inspect
and clean the AVR's enclosure, including gaskets, seals, and paint, and perform
any necessary repairs or replacements.
Conclusion:
The
selection and installation of 11kV AVRs on 11kV electricity distribution
feeders in Pakistan are critical for maintaining stable voltage levels,
improving power quality, and ensuring reliable electricity supply. Careful
consideration of factors such as load demand, type of AVR, reliability of
manufacturer, and proper installation and commissioning procedures are
essential for successful implementation. With proper selection, installation,
and maintenance, AVRs can significantly enhance the performance and efficiency
of electricity distribution feeders in Pakistan, benefiting both the utility
and the end consumers.
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