SPECIFICATIONS OF CABLES

SPECIFICATIONS OF CABLES

GENERAL SPECIFICATION

The specification for the parts of this contract mentioned below cover design, manufacture, assembly   and   testing  at  the  manufacturer’s factory  as  well  as  the  supply,  delivery, installation, testing and commissioning  of the cable at site.

CLIMATIC CONDITIONS

The climate is tropical and has marked Monsoon character with seasonal changes from humid, warm, rainy season, summers to cool and dry winters. Maximum temperature occurs during the period from April to May reaching approximately 43 deg. C    (110 deg. F) with a relative air humidity of 60% to 70%.

The annual mean temperature is approximately 29 deg. C (84 deg. F). During the rainy monsoon month from June to September, the average relative air humidity is 80% and reaches extreme values up to saturation point during longer periods. The annual rainfall, most of which occurs from June to September is 2000mm to 2500mm.

OPERATING CONDITIONS

The cable will be connected to the 11KV or 415 volts 3-phase or 220 volt single phase, 50 Hz Bus of Power Development Board/REB/ DPDC/DESCO Bangladesh.

STANDARDS

All equipment and materials must be in conformity with the most recent relevant Bangladeshi laws, standard rules and regulation. Particular attention is to be paid to the Electrical Act 1910 and Electricity Rules 1937 (as amended in 1946). All equipment and materials to be supplied which required any form of approval by the Bangladesh Government or a Local Authority like PDB/ DPDC/DESCO or REB must satisfactorily pass all inspection and tests procedures imposed by them.

Otherwise, all the equipment and materials must be in conformity with the most recent international rules, regulation, standards and recommendation: IEC.

STANDARD DATA

The following standard values for high and low voltage are standard in Bangladesh.

Distribution bus High Voltage                           :               11KV,

Maximum system High Voltage                       :               12 KV.

Distribution bus Low Voltage                            :               415/240 V

FREQUENCY

The standard power frequency in Bangladesh will be: 50Hz.

DESIGN & CONSTRUCTION REQUIREMENTS

All Cables are to be in accordance with the latest recognized rules of workmanship and  modern engineering practice and must be suitable in every respect for continuous operation at maximum output under the climatic conditions as specified above.

MATERIAL REQUIREMENTS

Conducting materials for cables must be of 99.99% pure annealed stranded copper and insulation of thermoplastic materials based on PVC or XLPE for HT and LT Cables shall be complying with relevant IEC/VDE/BS/BDS standards.

PROPERTIES OF PVC COMPOUND

1. Tensile Strength

Thermoplastic PVC compound	Tensile Strength
	Before Ageing (kgf) min	After Ageing at 80+2◦C for 7 days (kgf) min	Difference after ageing % max
Insulation mixture     ( LT Cables)	125	125	25
Insulation mixture      ( HT Cables)	150	150	25
Sheath mixture	100	100	25

2. Elongation

Thermoplastic PVC compound	Elongation
	Before Ageing % min	After Ageing at 80+2◦C for 7 days % min	Difference after ageing % max
Insulation mixture      ( LT Cables)	125	125	25
Insulation mixture      ( HT Cables)	100	100	25
Sheath mixture	150	150	25

3. Thermal Stability at 200◦C

Thermoplastic PVC compound	Thermal Stability at 200◦C
	Volume resistivity at 70◦C Ohm.cm	Before Ageing % min	After Ageing % min	Deformation under pressure at 70◦C. Depth of indentation % max	Heat Shock at 150◦C	Shrinkage at 150◦C % max
Insulation mixture ( LT Cables)	10	80	80	50	No Crack	4
Insulation mixture  ( HT Cables)	10	120	120	50	No Crack	4
Sheath mixture	-	40	40	50	No Crack	-

MARKING AND CODE

The Cables shall be marked and coded in accordance with BS, IEC, VDE or equivalent standards.

INSULATION CO-ORDINATION

The insulation of thermoplastic materials based on PVC or XLPE for HT and LT Cables shall be comply with relevant IEC/VDE/BS/BDS standards.

The insulation test voltage for Cables is as follows:

Rated voltage of the cables, KV	Single phase test voltage, KV	Three phase test voltage, KV	Direct test voltage, KV
0.6	4	4	12
3.5	11	11	33
5.8	17	17	51

TECHNICAL REQUIREMENTS

The Cable specified in the following items shall withstand the impulse levels and test voltages specified by the recommendations of IEC, as stipulated before. They must be capable of carrying the short time current for three seconds and must withstand the short circuit (Peak value) current.

The cable must be designed accordingly in order to withstand the mechanical short circuit stresses.

They must contain all technical particulars which are mentioned in the Schedule of Technical Data.

The Owner reserves the right to have routine tests carried out on each type of equipment at the manufacturer’s factory in the presence of his representative.

The single bars shall be marked by the colors as per IEC, VDE or BS standard.