Career Episode 2

Your Full Name: Md. Abdullah Al MamunYour Date of Birth: January 01, 1985Your Email: mamun0259@yahoo.comYour Address: Kallyanpur 132/33KV Grid Substation

Mazar Road, Gabtoli, Mirpur-1Dhaka-1216

Your Phone No: +88 017 1163 1820Field of Engineering : Electrical & Electronic EngineeringTotal Years of experience: 5+ Years

A. Introduction: CE 2.1

Project / Thesis Title: Replacement of damaged 132KV Bushing of 132/33KV Power Transformer of National Grid (PGCB).

Name of the Organisation (Company/Educational Institute) where the project held on:Power Grid Company of Bangladesh Ltd. (PGCB). I joined PGCB in 06 November of 2008 as an Assistant Manager (Technical).

Creation of Power Grid Company of Bangladesh Ltd. (PGCB) is a part of the reforms being initiated by the Government.

Due to different type of complexity in the power system it was an urgent necessity to differentiate the Transmission System from the whole power system of Bangladesh. Bangladesh Power Development Board (BPDB) was assigned to manage power transmission system, power generation and power distribution through out Bangladesh before formation of Power Grid Company of Bangladesh Ltd. (PGCB). PGCB was established on the 21st November, 1996 as a fully BPDB owned company with an authorized capital of Tk.10 billion under the Power Sector Reform Program of the Government. PGCB has been running under the Company Act 1994.

At beginning the Board of Directors of PGCB consisted of 10 Directors. Out of them, 3(three) were from BPDB, 4(four) from non Government organizations and the remaining 3(three) from PGCB. Currently the number of directors of the Board of Directors has been reduced to 8(eight), amongst them 1(one) is from Ministry, 1(one) from BPDB, 5(five) from out of government sector and the number of directors from PGCB itself has been reduced to 1(one), the Managing Director.

It is mentioned that PGCB was formed under the restructuring process of Power Sector in Bangladesh with the objective of bringing commercial attitude including increase efficiency, establishment of accountability and dynamism in accomplishing its goals. PGCB is mainly concerned with the operation, maintenance and development of the power transmission system all over the Bangladesh. Expansion of the grid network like installation of new transmission line and grid substations are its assigned prime responsibility. After formation of this company the existed transmission system had been gradually handed over to PGCB from BPDB and Dhaka Power Distribution Company Ltd. (DPDC). On the 31st December 2002 PGCB took over full responsibility of the total transmission system of Bangladesh.

Generated power of different power plants all over the country is evacuated and transmitted through PGCB's integrated grid system by 230 kV and 132 kV transmission lines and substations. In 1996 when PGCB was formed, the total length of 230 kV and 132 kV line were 838 circuit km and 4755 circuit km respectively which increased to 1144 circuit km and 4962 circuit km respectively in 2000-01 fiscal year. At present there are 2647.3 circuit km of 230 kV line and 6077.44 circuit km of 132 kV line

throughout Bangladesh under PGCB. It has been implementing optical fiber network, that is OPGW parallel to its over head transmission lines to establish digital communication system to improve the control and monitoring of the transmission system. This optical fiber network will be utilized for the telecommunication and IT network of the country as by product. This network is potential to generate huge income for PGCB in near future.

The transmission structure of PGCB up to June 2012 is as follows:

230 kV Line 2,647.3 circuit km 132 kV Line 6,077.44 circuit km 230/132 kV Substation 13 Nos. 6675 MVA 132/33 kV Substation 83 Nos, 9146 MVA

Following are the initial activity of DESCO which includes:

1. Wheeling of power from Generation to the distributor end2. Operation & Maintenance of the Sub-stations and Transmission Line to ensure uninterrupted

power supply to the distributor.3. Increasing Transmission efficiency.4. Planning, Design and installation of 400/230KV, 230/132KV & 132/33KV Sub-stations and

400KV, 230KV & 132KV Transmission lines.

The service territory of PGCB is all over the Bangladesh. Today PGCB is the most successful organization in Bangladesh with private & public partnership.

Time period (from and to) of the project: September 16, 2011 to September 18, 2011

Geographical location where the experience was gained: Dhaka, Bangladesh

My Position / designation of this project: Engineer In-charge.

B. Background: CE 2.2

The nature of the overall engineering project:

PGCB is the only bulk power transmission company in Bangladesh. So, it is very important to maintain availability of all equipments (grid transformers) and transmission lines with least possible interruption. This organization always tries to maintain all international standards for wheeling of Electricity. About 60% of the total generation is consumed in the Dhaka city. There are several very important loads supplied by the distributions companies those are being fed by ‘Kallyanpur 132/33KV Grid Sub-station’. If I arrange them in the order of importance those are a) National Parliament Building of Bangladesh, b) Residential building of Primeminister of Bangladesh (called Ganabhaban), c) Planning Commission of Bangladesh, d) total of ten hospitals (government and private owned) in Agargaon area, e) Local office of the World Bank, f) Local office of Asian Development Bank, g) Bangabandhu International Conference Centre (BICC), h) government provided residential buildings for member of parliament (MP Hostels) etc. All these including local residential area are fed by Kallyanpur 132/33KV Grid Sub-station.

As mentioned earlier PGCB is trying to transmit interruption free and quality power to the distributor and hence the consumers. For these reason PGCB tries its best to take preventive & corrective action as necessary and applicable to avoid any fault resulting interruption of power supply to the consumers. We try to remove any kind fault at the earliest possible time. This project was a corrective action and emergency maintenance for PGCB as well as me.

CE 2.3

The project objectives: Replacement of Damaged 132KV Bushing Testing the transformer Bring the Transformer in operation

CE 2.4Nature of My Particular Work Area:

In-charge of the whole sub-station named ‘Kallyanpur 132/33KV Grid Sub-station’. Responsible for smooth operation and maintenance of Sub-station as well as associated

132KV transmission lines. To guide and supervise the shift engineers working for operation of the sub-station and

perform the role of superior of them. Reporting any abnormal or emergency situation to the National Load Dispatch Centre (NLDC)

and taking action according to their instruction. Preparing monthly maintenance schedule and execute the same by the technical team as a

team leader. Doing regular and emergency maintenance work. Maintaining prescribed clearance of transmission lines. Monitoring entrance of strangers in the compound and Ensuring security of the overall Sub-

station. Preparing monthly wheeling bill using the energy readings taken by shift engineers and forward

it to the Manager, Grid Maintenance Division, Dhaka (North-West) of PGCB. Preparing schedules for maintenance work of both sub-stations and transmission lines. Responsible for conducting annual maintenance work of substation which includes testing and

calibration of all equipments, testing & replacing and/or filling Transformer oil as required. Supervising the works executed by local/overseas contractors as required as the Engineer In-

charge, reporting to the superior and certifying the quality of work & invoice.

Taking initiative of doing any further modification and/or addition in the sub-station equipments/civil establishments etc. as required.

My Duties and Responsibilities with this project:

Analyze the amount of damage of the Bushing Unbolt the damaged one and replace with the collected new one. Analyze any other fault occurred Turn on the transformer after necessary testing

Chart of the Organizational Structure: CE 2.5

Project Costing/ Total Amount of the Project Valuation:

Managing Director

Director (O&M)

Director (P&D)

Director (Finance)

Director (Admin)

GM Transmission-1 GM Transmission-2

DGMs Grid Circles

DGM Grid Circle (Dhaka)

ManagersGrid Maintenance Divisions

(GMD)

Manager GMD Dhaka (North-West)

Assistant/Deputy Managers

Junior Assistant Managers & other staffs

Assistant Manager

ant Manager

Junior Assistant Managers

Foreman

Line Mans

Electricians

Other staffs

GM (P&D)

GM (Finance)

GM (P&A)

Cost of the project was not associated with me directly. I made proposals and specifications for the cracked bushing replacement work. We used our tools and the additional manpower required for the work other than technical staffs of our own was hired from other nearest substation of PGCB. The new busing was collected from the central store of the Grid Maintenance Division (GMD), Dhaka (North-West). That’s why there was no extra cost involvement in this work.

C. Personal Work Place Activities:CE 2.6

As the In-charge of Kallyanpur 132/33KV Grid Sub-station I was selected as the Team Leader for the cracked bushing replacement work. I started with the planning of the work considering previous records of another cracked bushing replacement by previous in-charge & Deputy Manager of this sub-station before I was appointed here.

On 16 September of 2011 at 12:30 I was working on my Desk. I visited the switchyard as a sound reached my ear such that something blasted there. During my visit one shift engineer was with me as I requested him to come over. We found that 132KV Bushing of Blue phase of one Transformer of total three 50/75MVA Power transformer got cracked. The transformer was still supplying one third of total connected load to the sub-station. At once we informed the National Load Dispatch Centre (NLDC) and requested consent of shutting the Transformer and examine the amount of Damage. At the same time I also informed the matter to the local distributor and requested to decrease the load to a level such that the other two 50/75MVA transformer can supply the connected load.

Within a very short period we got approval of shutting down the transformer. Again I inspected the cracked busing and came to a decision that the damage was not repairable and need to be replaced. I informed it to my superior, Manager of Grid Maintenance Division (GMD), Dhaka (North-West), He advised me to prepare a proposal and take immediate action.

CE 2.7My proposal: Considering the Load scenario of the sub-station I proposed an immediate replacement of the cracked busing and bring the 50/75MVA transformer in operation. My proposal was to look for the new bushing in central store of Grid Maintenance Division (GMD), Dhaka (North-West), and in store of other division of PGCB at a time, gather transformer oil and bring the centrifuging machine from Mirpur 132/33KV Grid Sub-station of GMD, Dhaka (North-West). Start the replacement work gathering all these equipments and logistics.

The authority found my proposal appropriate and instructed me to start the project.

Technical Specification of 132kV Porcelain Type Bushing

GUARANTEED TECHNICAL PARTICULARS OF 132KV CONDENSER BUSHING

Sl. Description Purchaser's Requirement

No.1. Rated Current (Ir) 1250 Amp.2. Rated Voltage 145 kV3. Rated frequency 50 Hz4. Type of Insulation oil impregnated paper5. Impulse Withstand(1/50 wave) 650 kV peak6. Minimum Withstand voltage (1 minute

Power Frequency)305 kV

7. Minimum Surface Creepage Distance 3800 mm (min.)8. Total length 2600mm to 2900mm9. Air end dimension 1800mm to 2020mm10. Oil end dimension 800mm to 880mm11. Top cover to top terminal 225mm to 300mm12. Flash over length 1495mm to 1550mm13. Top terminal Ø60mm, 125mm14. CT space 300mm to 320mm 15. Metallic bow Ø 230mm to Ø 300mm 16. Oil end max. dimension Ø 144mm to Ø 145mm17. Fixing flange Ø 335 mm18. Fixing flange PCD Ø 290 mm19. Fixing flange holes Ø (15mm to 16mm) ×12 nos.20. Base plate Ø 130mm21. Arching horn gap setting 740mm to 990mm Adjustable22. Tube ID Ø 38mm

CE 2.8Technical Details of the Work:

As a sound came from the switchyard at about 13:00 of 16/10/2011 I visited the switchyard along with one of my shift in charge and two technical staff. After visual inspection we observed that the yellow phase 132KV bushing of 132/33KV Transformer named GT-1 of capacity 50/75MVA (ONAN/ONAF) got cracked. Oil came out of the transformer. The transformer was still in operation and sharing one third of the total load of the sub-station. Instantly I returned control room and informed the National Load Dispatch Center (NLDC) the fact and the local distributor to decrease the load of the sub-station to a limit that the other two 50/75MVA (ONAN/ONAF) Transformers in parallel can serve. Within few minutes we got consent of shut down from NLDC. Turned the transformer OFF and went for visual inspection closely with my team once again.

After very close visual inspection we found that our previous assumption was correct. The yellow phase bushing got cracked. I informed it to my management and appealed for permission of taking action to change the cracked bushing. I made a proposal within very short period and submitted to the Manager, GMD, Dhaka (North-West) of PGCB, and my controlling officer. He showed it to the management and they found the proposal appropriate. They made me the team leader and instructed to start the work.

Implementation and commissioning:CE 2.9

This time I was given a team of eleven members including me. My team consisted of two Junior Assistant Managers (Technical) having diploma degree in Electrical Engineering, two Foremen, seven Technical Attendants.

My first job was to collect the logistics/materials and tools required for the work. Getting permission to start the work I split up my team in three groups. The first and the second group were used to collect required logistics/materials. The first group was assigned to collect Transformer Oil from Store of Grid Maintenance Division (GMD), Dhaka (East), PGCB. And I sent second group to collect the new bushing from store of this Grid Maintenance Division (GMD), Dhaka (North-West). At the same time I communicated with other Grid Maintenance Division of PGCB close to my work place to arrange any alternate one if required. My communication returned zero result. The third group was engaged to prepare the site for replacement of the cracked bushing with a new/defect free one.

First team brought about 1,000 liter of Transformer Oil. The second team brought a similar bushing from our store. Within first eight hours I got all required materials & tools gathered for the work.

I checked the collected bushing by visual inspection first and then tested the insulation resistance. I found the inspection hole of the oil level in the bushing cracked and hence the insulation test result in satisfactory. Instantly I decided to manufacture the glass on the inspection hole by tempered glass collected from local market. According to my instruction my workers opened the glass cover on the inspection hole and poured out the insulation oil inside it. I instructed them to wash the inside of the bushing by shaking gently using new insulating oil. They did as I said and finally filled up it by tested new insulating oil. The oil had a dielectric strength of 65KV/2.5mm. Then we placed the locally manufactured glass cover on the inspection hole of the bushing and tested again. This time we found satisfactory result measured by High Voltage Insulation Resistance Measurement Test Set called the test ‘Meager Test’.

At the same time another group was engaged to pour out the transformer oil inside it so that, the cracked bushing can be unbolted from the Transformer Body without any loss of oil. The oil was kept in a rubber tank passing through a centrifuging machine. As the oil inside the main tank of the transformer was poured out to the required level I instructed my team to unbolt the Bushing.

The team unbolted the bushing carefully. During unbolting they were sincere about the lead inside the bushing so that it did not fell inside the transformer. After unbolting the cracked bushing we checked the lead and found that it was seriously damaged. At that situation I had to change my plan.

I instructed the team to pour out the complete oil from the transformer tank so that they can enter into the transformer and inspect any possible damage at the core to lead joint. They did so and one foreman and one technical attendant entered inside the transformer. They checked the joints very carefully and found no other sign of damage.

I made a plan to replace the lead anyway. We used the copper rod provided by the manufacturer along with the new Bushing. I cut 8 inches of the rod, made hole of diameter equal to the flexible copper lead of the diameter from both sides, kept a knurling point at the middle of the rod. I used this rod for joining the two part of the lead. We entered the two parts of the lead in the rod from both side and punched properly. We did not replace the original lead

as it was not possible to make the joint as tight as it was made by the manufacturer at the factory.

After making the joint I instructed the team to measure the contact resistance of the new joint made. They did it and found the measured result satisfactory. Then I instructed them to install the new Bushing to its original position on the transformer. They did it successfully.

As the bushing was replaced successfully I instructed the team to vacuum the transformer main body. During the vacuum process I made sure that the valve of the radiator fins to transformer main tank were locked to avoid any crack on them. Vacuum was done within a shorted period. I did this to ensure that there was no moisture inside the transformer before filling it with well centrifuged oil. Then I instructed the team to fill the transformer with oil. Before fill the oil we took several samples to test the dielectric strength. I found the result satisfactory. The value of dielectric strength was 65KV/2.5mm.

The transformer was then ready to test. I did Meager Test using high voltage insulation resistance measurement test set and ratio test by supplying 0.415KV to the 132KV side. Both test returned satisfactory result. The transformer was then ready to go in operation.

I made a meeting with my management along with my technical team. We all discussed about the work done and consulted the test result found. At the end we came to a decision that the transformer will be turned on without load as usual and would be kept unloaded for about 15 minutes and then it will be loaded if it withstands. We requested the National Load Dispatch Center (NLDC) for permission to turn on the transformer.

NLDC allowed us to do the operation and we turned on the transformer as decided in the meeting. Finally I arranged another meeting with my management and the technical team. I thanked all the members of my team for their active contribution in the work.

The Managing Director, Director (O&M) of PGCB and other visitors are watching the damaged lead inside the cracked bushing.

Workers unbolting the cracked bushing

Foreman inspecting any damage on 33KV side

It was me checking the joint made between bushing and Aluminum pipe to the Bus.

CE 2.10Project submission / presentation: After successful completion of the project I made a documentary and visual presentation in front of PGCB management. I explained all the features of the project including proposal, estimation, work implementation, trouble shooting and successful completion of the project. I was asked many questions regarding project implantation and they were satisfied with my answer.

CE 2.11Technical problems I solved:

In this project we faced some difficulties during replacement of the cracked busing.

The selected busing was cracked on the level indicator glass and left a suspect of causing low insulation resistance of the oil inside it. First of all I made a decision to measure the insulation resistance of the busing using High Voltage insulation resistance test set. The test result disappointed me. I purchased tempered glass from local market and made a similar piece of glass that was cracked. At the same time I poured out its insulating oil. I filled the busing with new oil that had a satisfactory insulation test result. Placed the glass piece to its position and used a gasket to make it airtight. Finally I measured the insulation resistance of the bushing once again using ‘High Voltage Insulation Resistance Measurement Set’. I found the result satisfactory and proceeded for installation to its position on the transformer.

I found that the connecting lead from the winding terminal to the top of the bushing was damaged seriously at about middle point of the bushing. I had to make change in my plan. We used the copper rod provided by the manufacturer along with the Bushing. I cut 8 inches of the rod, made hole of diameter equal to the flexible copper lead of the diameter from both sides, kept a knurling point at the middle of the rod. I used this rod for joining the two part of the lead. We entered the two parts of the lead in the rod from both side and punched properly. We did not replace the original lead as it was not possible to make the joint as tight as it was made by the manufacturer at the factory.

I faced another problem when connecting the bus conductor with the top of the bushing. The existing connector was not suiting with the new Bushing and the fittings with the new Busing was not matching with the bus conductor fittings. I was in hurry to turn on the transformer.I made a little change in the fittings. Instantly I used another aluminum alloy plate to match the two fittings. I used spare aluminum plate that I had in my store. The thing that I had to do was to make holes matching the both fittings. As we connected the bushing I instructed the foreman to measure the contact resistance. The value of the contact resistance was in satisfactory limit.

CE 2.12

Meetings with other departments:

Starting from the detection of the fault I made several meeting with my team as well as other department. My first meeting was with my technical team and the management together to express my plan of replacing the bushing. As the authority decided to execute my plan I made my technical team to understand what to do and how to do.

My next meeting was with the distribution companies and the In charges of other adjacent grid sub-stations. This meeting was to manage the loads of the substation by feeding the loads of this sub-station from other grid sub-stations. My target was to avoid any load shedding due to this emergency maintenance work. The meeting was successful and the responsible persons agreed to make arrangement of shifting the loads to other sub-stations. This reduced the amount of load shedding to the minimum level.

Finally I made my third meeting again with my technical team and the management to examine the related test results found after replacing the cracked bushing. We came to a decision that the test results was satisfactory and the transformer could be brought in operation.

CE 2.13Team management:

I called my technical for a meeting every day before beginning and end of the day. In the meeting every one was allowed to participate in open discussion on problems of the day. Everyone had freedom of expressing their observation and giving suggestion to overcome the difficulties and complete the work in time. This process was very effective to get prompt solution of any problem.

CE 2.14Time Management: I was very punctual and motivated the team to follow the time schedule for the project. I always divided work to the team members so that work load is equally shared and work completes in time. I had regular meeting with my co-workers to check the progress of project. In the meeting at the end of the day I checked progress and pointed out problems in the process which may affect project completion time. I solved all those problems found at each meeting. Again I maintained communication with the National Load Dispatch Center (NLDC), the local distributors (Dhaka Power Distribution Company Ltd., Dhaka Electric Supply Company Ltd. and Dhaka Palli Biddyut Samiti-1 and my management) to update them the status of the work and probable time of completing the project. This helped to make the load management plan effectively.

Occupational Health and Safety Management issues in this project: CE 2.15

During replacing the cracked bushing safety was a crucial issue. It was a Air Insulated Switchgear (AIS) sub-station. All other parts of the sub-station were live and some of them were very close of the Transformer on which we were working. During start of the day it is almost dark. It was raining when we were working on the transformer. I was very careful about the wet parts and the live parts to avoid any kind of accident. I used an exhaust fan to exhaust the gases produced in the transformer tank as the workers had enter into the tank to make the compression joint on the lead ‘coil to the top of the bushing’. I vas sincere to take safety measures to avoid any kind of accident. In each meeting I instructed the workers about the safety rules. I was always very strict to the workers to wire helmet, gloves and safety shoes etc. to ensure the safety of my team. So I did not face any accident during this project.

CE 2.16

Outcomes of the project:

Successful replacement of the cracked bushing caused a fault free transformer. It helped the substation to supply power to its consumer at its original capacity. It also enhanced the reliability of the substation.

CE 2.17

Project contributed to improve socio economic situation:

This project is very important in respect of customer service. As PGCB is the best and profitable power Transmission Company in Bangladesh customers expect more and more improvement of quality service and reliable power. Replacement of the cracked bushing prevented any serious damage of the 50/75MVA (ONAN/ONAF) transformer and saved huge money of PGCB. It also reduced load shedding due to damage of the transformer until it would be replaced by another one.

D. Summary:CE 2.18

This project is not an ordinary project but very important for the local distributor and the consumers as well as the image of PGCB. Installation of a new bushing on a power transformer improved system and also increased my practical knowledge. I acquired many experience of regarding human resource management, team management. During this project I had to communicate top management to line technician which improved my management skills. I arranged some training programs on the international safety rules and regulations for all the team members, form my experience management has decided to conduct this training among all technical hands.

CE 2.19References:

I got all required information from the (1) User Manual of the Transformer, (2) Drawing and Instruction of Installation provided with the new bushing by its manufacturer, (3) my senior colleagues of PGCB and (4) Internet, which helped me to complete this project successfully.