Piping Project

SPECIFICATION FOR    ELECTRICAL CABLES

This specification covers the minimum requirements for the design, manufacture and testing of high and

low voltage power cables, control and earthing cables for the SOUTH PARS GAS FIELD

DEVELOPMENT PHASES 20 & 21, ASSALUYEH / SOUTH PARS GAS FIELD PERSIAN GULF,

IRAN.

Electrical system voltages

33kV 50 Hz 3 phases neutral resistance earthed

11kV 50 Hz 3 phases neutral resistance earthed

6kV 50 Hz 3 phases neutral resistance earthed

400V 50 Hz 3 phases solidly earthed

230V 50 Hz 1 phases solidly earthed (lighting system)

230V 50 Hz 1 phases isolated from earth (UPS system)

                                                                                                                                                                     48VDC - unearthed

                Environmental conditions

Environmental conditions shall be as per Basic Engineering Design Data, "DB-SP2021-ON-PR-999-P332-

0204".

Nevertheless all equipment shall be capable of continuous operation at 48°C without deleterious effect.

Insulating material                                                Insulation grade– service voltages

33kV system                   19/33 kV (36 kV)                                     (XLPE)² or (EPR)¹ for LV cables.     

11kV system                   8.7/15 kV (17.5 kV)

6kV system                    6/10 kV (12 kV)

400V/230V systems      600/1000V         

48VDC                          600/1000V

                                           Polyvinyl chloride (PVC) optional for internal air conditioned building use only.

Insulation withstanding        XLPE            PVC

                                                                                           70^ºC                           90^ºC     at 100% continuous load

                                                                                 160°C                          250°C                  during short circuit

5.3 Cross sections

• Minimum cable cross section shall be:

- 1.5 sqmm for RTD cables

- 2.5 sqmm for control (digital signal)

- 2.5 sqmm for LV power and lighting cables

- 1 sqmm for analogue signals

- 35 sqmm for MV power cables 

• For high voltage, the following cross sections shall not be exceeded:

- 240 sqmm for three-core armoured cables

- 300 sqmm for single core cables

• For low voltage the limits shall be:

- 240 sqmm for a cable whether armoured or not, up to a maximum of three conductors

- 400 sqmm for single core cables

• Multi-conductor cables

Cross section of phase cores (sqmm)            Cross section of neutral cores (sqmm) 

S                                                                                            S<=25

16                                                                                             35

25                                                                                             50

35                                                                                             70

50                                                                                             95

70                                                                                            120

70                                                                                            150

95                                                                                            185

120                                                                                          240

                                                                                                                      300                                             150

- When a multi-conductor cable includes a protective core, it shall be sized according to the following

table:

Cross section of phase cores (sqmm)             Cross section of protective cores

S ≤ 16                                                         S  

16 < S ≤ 35                                                16

                S/2          S ≥ 50