Successful Case of 263 Units of 33kV Oil-immersed 32-step Voltage Regulator Controller Project in Bangladesh

Successful Case of 263 Units of 33kV Oil-immersed 32-step Voltage Regulator Controller Project in Bangladesh

01 Overall Project Overview

1.1 Project Background

In June 2024, 263 units of 33kV oil-immersed 32-step voltage regulator controller were officially delivered and applied to the Bangladesh Medium Voltage Distribution Network Upgrade Project. R&D and manufactured by Rockwill, these devices are used for voltage stability regulation, load fluctuation adaptation and power supply quality improvement of the Bangladesh power grid. The equipment has been installed and put into operation in multiple 33kV substations and industrial parks in Bangladesh, with stable and reliable operation status.

The 32-step voltage regulator controller is the core voltage regulation equipment in the medium voltage distribution network. It can accurately stabilize voltage when the grid voltage fluctuates sharply, compensate line voltage loss in real time during dynamic load changes, effectively solve problems of over-voltage, under-voltage and excessive voltage fluctuation, and greatly reduce the failure rate of electrical equipment and power outages. It is a key equipment for the upgrade of urban and rural distribution networks and the improvement of industrial infrastructure in Bangladesh. The 33kV oil-immersed 32-step voltage regulator controller delivered this time is compatible with the 50Hz operating frequency of the Bangladesh power grid, and is customized and optimized for the complex local environment of outdoor high temperature (maximum temperature up to 40℃ and above), coastal high humidity and more dust. It adopts a fully sealed oil-immersed cooling system and high-strength anti-corrosion shell, with high-precision voltage regulation capability. It can stabilize the output voltage within ±1% when the input voltage fluctuates by ±20%. At the same time, with a complete localized after-sales service system and remote monitoring function, it has been highly recognized by the Bangladesh Power Development Board and various project owners, providing stable and reliable power guarantee for local industrial production, residents' lives and infrastructure construction.

1.2 Technical Parameters

1.3 Drawings

For more information about MV step voltage regulator, please contact us!

02 Product Manufacturing

2.1 Winding and Curing of 32-step voltage regulator controller Coils

The winding of step voltage regulator coils is a core process for the voltage regulation accuracy of the regulator. Fully automated CNC winding equipment is adopted to strictly control the winding density and turns error, ensuring that the coils are wound uniformly and compactly with an error controlled within ±0.5%, thus guaranteeing voltage regulation accuracy. After winding, a vacuum pressure impregnation (VPI) process is applied, where the coils are immersed in high-temperature resistant insulating varnish. Through vacuum deaeration and high-pressure curing treatment, the insulating varnish fully penetrates the gaps between the coil turns, forming a dense insulating layer.

The cured coils shall undergo special tests such as insulation resistance and dielectric loss measurement to ensure that their insulation performance meets the requirements. They are able to withstand outdoor voltage surges and environmental erosion in Bangladesh, avoiding problems such as insulation aging and breakdown during long-term operation.

2.2 Assembly of the 32-step Voltage Regulator Controller and Transmission System

The step voltage regulator adopts a modular assembly method, precisely assembling high-precision inductive voltage regulation mechanisms, transmission gears, adjusting shafts and other components. The fit clearance between parts is strictly controlled to ensure smooth transmission and accurate voltage regulation action. During assembly, long-lasting high and low temperature resistant grease is applied to the transmission components, suitable for the temperature range of -5℃ to 40℃ in Bangladesh, avoiding solidification at low temperatures and loss at high temperatures, and preventing transmission jamming.

After assembly, a mechanical action test is carried out, repeatedly simulating actions such as voltage regulation and locking to ensure fast response speed, stable and smooth operation without jamming. The mechanical life reaches more than 2,000,000 times, meeting the requirements of long-term frequent voltage regulation in the distribution network.

03 Testing of 32-step Voltage Regulator Controller

• MV step voltage regulator component fit accuracy test: Detect the fit clearance of the voltage regulation mechanism, transmission gears and adjusting shaft to ensure compliance with assembly standards, guaranteeing smooth transmission and accurate voltage regulation action.
• MV step voltage regulator grease compatibility test: Verify the performance of the long-term high and low temperature resistant grease within the temperature range of -5℃~40℃, confirming no solidification at low temperatures or loss at high temperatures to prevent transmission jamming.
• MV step voltage regulator mechanical action performance test: Repeatedly simulate voltage regulation and locking actions to detect the response speed, ensuring smooth and jitter-free operation.
• MV step voltage regulator mechanical life test: Verify that the mechanical operation life reaches more than 2,000,000 times to meet the requirements of long-term frequent voltage regulation in the distribution network. 

04 Packaging and Transportation of 32-step Voltage Regulator Controller

4.1 Packaging

• Customized iron racks are used for reinforced packaging, with internal cushioning materials such as foam and air cushions to effectively resist vibration, extrusion and impact during transportation.
• Comprehensive protective measures are adopted for the transformer body and supporting components to isolate external influences such as vibration, moisture and collision.
• Markings such as cargo weight, overall dimensions, destination port address and contact phone number are clearly indicated on the exterior of the box to ensure standardized and traceable transportation and signing.

4.2 Transportation

• Transportation method: Seaborne transportation is adopted, which is suitable for long-distance transportation of large power equipment, featuring stable transportation and stable environment.
• Carrier: An experienced professional logistics enterprise is selected to ensure safe and on-time delivery of the equipment and assist with the completion of the entire customs clearance procedures.

05 Site Implementation and Summary for 32-step Voltage Regulator Controller

5.1 Site Implementation

This project is a distribution network voltage stabilizer renovation project in Bangladesh. The entire on-site installation, commissioning and commissioning process strictly follows IEC international standards and local distribution network construction specifications. A modular assembly method is adopted to the local high-temperature, high-humidity and dusty outdoor environment, and the standardized procedures below are implemented to ensure stable equipment operation:

• Comprehensive Preparation: Check the civil conditions of the installation base, inspect the appearance and insulation status of each modular component of the voltage regulator, prepare construction tools, weather-resistant and high-temperature compatible materials, and verify the equipment model to prevent mismatching and missing components.
• Modular Assembly: The medium voltage regulator is assembled in a modular manner to precisely install high-precision inductive voltage regulation mechanisms, transmission gears, adjusting shafts and other components. The fit clearance is strictly controlled to ensure smooth transmission and accurate voltage regulation. Long-lasting high and low temperature resistant grease is applied to the transmission components to adapt to the local climate and prevent transmission jamming. After assembly, a mechanical action test is conducted to simulate voltage regulation and locking actions, ensuring fast response, stable operation and a mechanical life of over 2,000,000 times, meeting long-term voltage regulation requirements.
• Housing Installation and Sealing: The core components of the voltage regulator are hoisted into the anti-corrosion housing and fastened. Key parts are treated with double sealing + weather-resistant adhesive to prevent rainwater and dust intrusion.
• Oil Filling and Wiring: Vacuum oil filling with oil purification equipment and micro-water detection are performed to ensure the transformer oil is qualified. The main circuit, intelligent module and lightning protection grounding connections are completed in accordance with specifications to ensure firm and standardized wiring.
• Mechanical and Electrical Commissioning: Mechanical action and electrical performance tests are carried out to ensure that the output voltage is stabilized within ±1% when the input voltage fluctuates by ±20%, complying with local power supply requirements.
• Environmental Adaptability Test: Simulate extreme high-temperature and high-humidity conditions on-site to verify the anti-corrosion, sealing and heat dissipation performance of the equipment, ensuring it is suitable for outdoor operation.
• Commissioning with Load: Conduct a 72-hour trial operation with load and test the grounding resistance (measured ≤3Ω, better than standard requirements) to ensure all equipment performance indicators meet the standards.

5.2 On-site Summary of the 32-step Voltage Regulator Controller

This upgrade and renovation project of the 32-step voltage regulator controller for the distribution network in Bangladesh strictly complied with IEC international standards and local construction specifications. A modular assembly method was adopted to improve construction efficiency and quality, adapt to the local high-temperature, high-humidity and dusty environment, and implement full-process quality control. During implementation, precise assembly, standardized sealing and comprehensive commissioning addressed issues such as transmission jamming and insulation attenuation of the voltage regulator, ensuring stable equipment operation. After a 72-hour on-load trial operation and joint acceptance by the owner, all test data met the standards, and the equipment was successfully handed over for operation and maintenance. The project effectively improved the voltage stability of the local distribution network and ensured power consumption quality, reflecting the adaptability and reliability of the voltage stabilizer and receiving high recognition from the owner. 

06 Full Life Cycle Operation and Maintenance Hosted Service

This service covers the entire life cycle from procurement and adaptation of the 32-step voltage regulator controller, installation and commissioning, daily operation, maintenance, fault handling to scrapping disposal. It is hosted throughout the process with dedicated personnel responsible, ensuring safe and stable operation of the equipment, traceable management and worry-free power consumption.

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