STP & ETP

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  STP     Sewage treatment platn (residential & commercial) ETP     Effluent treatment plant (industry) COD     Chemical oxygen demand (soluble & insoluble organic compound) (2hr to 3hr) (mg/l) BOD     Biochemical oxygen demand (organic compound) (3days to 5days) (mg/l) KEY POINTS: Outlet of STP 50mg/l Biproduct of anaerobic digestion is H2S & NH3 To reduce stink smell use ozone 

CABLE SELECTION

 CABLE



SELECTION OF CABLE SIZE BASED ON AMPERE

  • Upto 30 A divide the ampere value by 5
  • Inbetween 30 A and 125 A divide the ampere value by 4
  • Above 125 A divide the ampere value by 2
  • Then select the available/standard cable size nearest to the resultant value.

AVAILABLE CABLE SIZE AND AMPERE RATING

SIZE

AMPERE

0.5

2.5

1

5

1.5

7.5

2

10

2.5

12.5

4

20

6

30

10

40

16

60

25

80

35

140

70

280

95

380

120

480

150

300

185

370

200

400

240

480

300

600

630

1260

800

1600

1000

2000




PROPER METHOD FOR SELECTION OF CABLE SIZE

  • Current rating
  • Voltage drop
  • Inrush current
  • Short circuit current
  • Length of cable
selection = maximum (1, 2, 3, 4& 5)

Before calculating these terms we need some data
  • 1 phase or 3 phase
  • Voltage level
  • Insulation level
  • Insulation material
  • No of cores
  • Space between cables
  • Group of cables
Cable laying:

600mm clearance from the ground level upto 1kVA
1100mm clearance from the ground level upto 11kVA

Armoured cable:

SWA    steel wire armoured cable is used for multicore purpose
AWA    aluminium wire armoured cable is used for single core purpose

Insulation medium:

PVC      polyvinyl chloride (160'C)
XLPE    cross-linked polyethylene (250'C)

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