GENERAL CONSIDERATIONS : – Thermal short circuit capacity (for H.V Cables) ; – Voltage drop; – Current rating; – Maximum cable loop impedance for earth faults shall not exceeding 1s under solider earth fault conditions. It is meanly for long distance cables.

GENERAL CONSIDERATIONS

o Thermal short circuit capacity (for H.V Cables)

o Voltage drop

o Current rating

o Maximum cable loop impedance for earth faults shall not exceeding 1s under solider earth fault conditions. It is meanly for long distance cables.

1.1 Short Circuit Current Rating

The short circuit breaking current of the source switchboard also takeing into account the short circuit limiting characteristics of, e.g., fuse, relays, CBs. The fault clearance time associated with operation of the primary, see section 2.2.

1.2 Voltage Drop

Voltage drop under steady state and motor starting condition with standard (DEP 33.64.10.10-Gen.) and project requirements. In normally shall be follows

o Less than 5% based on continuous maximum current loading and rated voltage in A.C cables.

o Less than 20% of the rated equipment voltage during motor starting

o Less than 5% from min. system voltage at distribution board and the min. equipment operation voltage in DC cables.

1.3 Cable Current Rating

1.3.1 Rating factor for cable ampaciry

o Onshore

• Depth of laying (IEE wiring regulations 16th 19991)

Correction factor shall be considered if cables in enclosed trench 450mm wide by 300mm deep minimum. Correction factor shall be applied based on Table 4B3- Method 18 (Refer to appendix – C) Correction factor shall be considered if cables in enclosed trench 450mm wide by 600mm deep minimum. Correction factor shall be applied based on Table 4B3-Method 19 (Refer to appendix – C). Correction factor shall be considered if cables in enclosed trench 450mm wide by 760mm deep minimum. Correction factor shall be applied based on Table 4B3-Method 20 (Refer to appendix – C).

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