Underground cable

In(10) = 2.303 , and 2.718 details 

QUESTION 2

Details 0.69 ÷ 2.3 = 2 or 2.13 

QUESTION 16

QUESTION 16 ,17

QUESTION 29 ,30 ,31

QUESTION 32

QUESTION 33

QUESTION 34

QUESTION 36, 37

QUESTION 38, 39

QUESTION 40

QUESTION 41

QUESTION 42

Question 1

In(1.8) = 2.303 × 0.2553 ( log table) , = 0.5879

Question 3

In(2.5) = 2.303 × log x , = 2.303 × 0.0.3979 (log table ) =0.9163 , 

Question 4

In(1.96) = 2.303 × log (1.96) , = 2.303 × 0.2923 (log table) , = 0.673 

Question 5

In(3.3) = 2.303 × log10(3.3), = 2.303 × 0.5185 (log table), = 1.1938 , or 1.20397 

Question 6

In(1.8) = 2.303 × log10(x), = 2.303 × 0.2553 (log table) , = 0.5879 , 

Question 7

In((1.8) = 2.303 × 0.2553 =0.5879

Question 8

log 2.4 value = 0.3802 ( log table) 

Question 9

= log 10(3.5/2.5) = log 10 (1.4) = 0.1461 , 

Question 10

Log 1.8 solve question 7
Question 11

In(0.300/0.075) = In(4) = 2.303 × log10(4) = 2.303 × 0.6020 ,log table .= 1.3864 , 

Question 12

= In (0.015 ÷ 0.01) , =In(1.5) , = 2.303. × log10 (1.5) , = 2.303 × 0.1761 = 0.4055 , 

Question 13

Log 4 = 0.6021 log table 

Question 14

log 4 = 0.6021 log table 

Question 15

Question 18 

First term details 

Second term details 

third term details 

In(2) calculation details 

= 55.44 kv 

= Safe working voltage( rms) for cable = 55.44 ÷ √2 = 39.2 kv  , answer ✓

This example shows the utility of grading the cable , thus for the same conductor diameter (d)  and the same overall dimension (D) , the graded cable can be operated at a voltage ( 57.84 -39.20)= 18.64 kv (rms) higher than the homogeneous cable - an increase of about 47% , answer ✓

18.64 × 100 /39.2 = 47 % 

Question 19

In(1.875) details 

In(15) details 

In(8) details see 18 question = 0.6931

Details, In (1.6) = 0.470 

2.303 details 

Safe working voltage (rms) for the cable = 54.71÷ √2=38.68 kv answer ✓

Question 20

In(2) calculation details, question 18

In(3/2)=In(3)-In(2)  calculation details 

In(3) calculation details, 

So. In(3)-In(2) , 

1.0986 - 0.6931 = 0.4055 

39.38 kv/cm , answer ✓

Similarly, it can be proved that (3)

= 32.81 kv/cm answer ✓

In(2) = 0.6931details , question number 18

In(3/2) 0.4055 details , look above ↑

In(x) = 2.303×log10x , = 2.303 ×.3010 (log table)=0.6931, 

In(3/2) or In(1.5) = 2.303 × .1761(log table) = 0.4055 , 

..

Question21

In(1.55) = 2.303 × .1903 (log table) = 0.4382 

Loge4.2/3.1 ,= take In(4.2/3.1) = 1.3548 , 

= In(1.3548) = 2.303 × ( .1303 + .0013) log table = 0.303  , 

= In(1.2619) = 2.303 × .101025 ( log table) 

End