WAZIPOINT Engineering Science & Technology: February 2013

Friday, February 15, 2013

CONTRACTOR’S GENERAL RESPONSIBILITIES

What Would be Contractors Overall Responsible on Site During Work in Progress at Sites?


Unless stated specifically to the contrary in the schedule of departures submitted with the Tender with full supporting explanations, the Contractor will be deemed to have concurred as a practical manufacturer with the design and layout of the Works as being sufficient to ensure reliability and safety in operation, freedom from undue stresses and satisfactory performance in all other essentials as a working plant.

The Contractor is to include the whole of the Works that are described in or implied by the Contract document, to provide complete, fully operable, safe and efficient installations, in accordance with internationally accepted practice. All matters omitted from the Contract document which may be inferred to be necessary for the efficiency, stability and completion of the Works shall be deemed to be included in the Contract Sum.

Works shown in the drawing and not mentioned or described in the specification and works described in the specification and not shown on the drawings will nevertheless be held to be included in this Contract and their execution is to be covered by the Contract Sum.

The Contractor’s representative on the Site or his nominated deputy is to be given full responsibility and financial authority to enter into negotiations regarding points arising out of erection, so that the Work may be expedited with as few delays as possible.

Unless otherwise specified, the Contractor is to supply the whole of the labour and equipment required for the completion of the work.

The curriculum vitae of the Contractors head-office project staff and site engineers together with organizational diagrams shall be submitted to the Employer to demonstrate that adequate resources and staff of sufficient experience are being employed.

Until each section of the Contractor’s Works have been taken over by the Employer, the Contractor will be entirely responsible (save as is provided by the General Conditions of Contract), for such section of the Contract Works, whether under construction, during tests or in commercial use.



The Contractor shall check the electrical and mechanical connections to all plants supplied under the Contract and the connections to existing plant covered by the Contract before such plant is brought into commission and shall be responsible for the correctness of such connections in accordance with the Contract Drawings and the specification.

Wednesday, February 13, 2013

TRANSMISSION AND DISTRIBUTION SYSTEM PARAMETERS IN BANGLADESH

Restricted Working Period In Bangladeshi Electrical Project

Due to monsoon rain between July and September, work may slowdown. Due to traffic, work along /across road has to carefully plan. 

The Contractor shall obtain reliable Information concerning the conditions appertaining to the working areas covered by this Contract and shall plan his work in accordance with local conditions.


Transmission and Distribution System Parameters in Bangladesh

SYSTEM ELECTRICAL PARAMETERS IN BANGLADESH

230 kV Transmission System in Bangladesh
Normal Service Voltage              :   230     kV
Rated Voltage                            :   245     kV
Insulation Level -
Lightning Impulse Withstand       :  1050  kV
50Hz dry 1 minute Withstand      :  460     kV
Number of Phase                       :  3
Frequency                                 :  50       Hz
Switchgear Symmetrical Breaking Capacity     :  40  kA, 3 sec

System Earthing
The 230/132 kV auto transformers are solidly earthed

132 kV Transmission System in Bangladesh

Normal Service Voltage                               :           132     kV
Rated Voltage                                            :           145     kV
Impulse Voltage Withstand Level                 :           650     kV
Number of Phase                                        :           3
Frequency                                                  :           50       Hz
Switchgear Symmetrical Breaking Capacity   :   31.5   kA, 3 sec
Voltage Stability Limits            :           ± 10%            Volts
Frequency Stability Limits        :           48-51 Hz

33 kV Transmission System in Bangladesh

Normal Service Voltage                      :           33       kV
Rated Voltage                                    :           36       kV
Impulse Voltage Withstand Level         :           170     kV
Number of Phase                                :           3
Frequency                                          :           50       Hz
Switchgear Symmetrical Breaking Capacity   :   25       kA, 3 sec

The 33 kV system is solidly earthed at some of the 132/33 kV Grid substations and resistance earthed at some of the Grid substations.

At the Proposed 132/33 kV sub-station the 33 kV systems will be resistance earthed.

11 KV Distribution Systems in Bangladesh

Normal Service Voltage                              :           11 KV
Rated Voltage                                            :           12 KV
Impulse Voltage Withstand Level                 :           75 KV
Number of Phase                                        :          3
Frequency                                                  :           50       Hz
Switchgear Symmetrical Breaking Capacity   :   25       kA, 3 sec
System earthing                                         :           Solid Normal

Low Voltage AC System in Bangladesh

Normal Service Voltage                        :           400/230 volts
Rated Voltage                                     :           415/240 volts
Number of Phase                                 :           3 phase 4 wire
Frequency                                           :           50Hz
Switchgear Symmetrical Breaking Capacity   :   22kA, 3 sec
System earthing                                  :           Solid

D.C System in Bangladesh

For D.C. motor driven auxiliaries, tripping, indicating lamps and controls.
Normal battery voltage                :           110V nominal for new sub-stations.
Tolerance on rated voltage         :           + 10%, -15%
Voltage at various existing sites :           30V, 48V, 110V, 220V, 250V.

For Supervisory and Telecommunications

Nominal System Voltage              :          48V
Normal float charge voltage       :           53V
Tolerance on rated voltage         :           +1V, -7V



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