POWER CABLING OF 0.4 kV FROM ATCO “MDB” OFFICE UPSTREAM OF THE BASE DRILLING NEW AGDS.
In order to connect the new AGDS, located at Drilling Base territory, from the ATCO “MDB” office (drawing number O-4800-R-5192 and O-4800-P 5201, Revision В), it is necessary to route the cable line, 0.4 kV. The cable trenching and grounding method is used at the crossings with plastic pipes. Highway cable length is 450m, cable tag number is 4800-РF-99388.
It is supposed that the voltage loss according to the TCO standard shall be not more than 2% Power backup is intended from the gas generator being installed at the AGDS site, maximum cable length from the generator to the AGDS switch board is not more than 15m, cable tag number is 4800-РF-99389, switch board number is 4800-MCC-35264 (drawing number O-4800-R-5191, Revision А). Supposed load at the AGDS is about 13.4 kW.
The existing cable feeding the MDB from Drilling Base SS number 3,is laid ASB GRADE- (3x240+1х120mm2), cable tag number is 4800-РF-1733, grounding cable laid separately, the cable size is 70mm2. It is supposed that the voltage loss according to the TCO standard shall be not more than 2%
Drawing number is O-4800-P-1426, Revision 4.Drilling Base. Distribution of 0.4 kV. cable. Single line diagram.
2.CABLE SIZE CALCULATION
The current design value on the switch board is 4800-MCC-35264 0,4kV with cosφ=0,85
Iр=Р÷U ×√3 х cosφ
Iр=13,4÷0,38×√3 х 0,85
Iр=24А
Cable size with copper-conductors based on the continuous current PUE ( Electrical Installation Code) of RoK 2013 Annex 5, Table 6 when the cable is laid in the earth and partially in the air 2.5mm2
Cable size calculation of 0,4kV based on the economic current density PUE ( Electrical Installation Code) of RoK 2013 Annex 5, Table 36, the number of used hours of maximum load per year is more than 5000 s=IP to 2=24 up to 2,0=12mm2 Take the cable with copper conductors which armored size is 3x16+1х10mm2
Voltage loss calculation CL of 0,4kV with length of 450 m in normal operation mode
∆∪= √3∙100∙ Iр ∙L(r0 ∙ cosφ +x0 ∙ sinφ) / Unom ,where PP - active power, kW (operating mode ) r0 - is active cable resistance on the section of the line of 450m ( tabulated value is x 0,45km) x0 - reactive cable resistance on the section of the line of 450m (tabulated value is x 0,45km- this data value can be neglected) ∪n-voltage line, B
∆∪=1,73х100х24х0,45х1,16х0,85/380=4,85% - losses outside of the permissible.
Take the cable with copper conductors with armored size is 3х50+1х25mm2 ∆∪=1,73х100х24х0,45х0,387х0,87 / 380=1.65%
The remote load from the AGDS switch board – is an electric valve at the block valve assembly (UZA) near the tie-in point 0,18kW, current is 0,32A, distance is 200m Take the cable with copper conductors together with armored size is 5x2,5mm2 ∆∪=1,73х100х0,32х0,2x7,56х0,85/380=0,19%
Total losses are: ∆∪=1%+2%+1,65%+0,19%=4,84%, where: 1%- losses at the substation number 3 permitted according to the TCO standard 2%- losses before the ATCO board ATCO permitted according to the TCO standard 1,65%- ATCO board losses to the AGDS board 0,19%- losses to the remote Consumer
