Table 9 Effective Z

[Derick]

Guys I have problem with understanding Table 9 and note #2

Ze=R x pf x XL

For example: 400 AL MCM in PVC Ze=0.066 from table 9

Based on formula above shouldn't the sum of 85%R and XL be the same as (0.066)? by taking values from XL and R

400 AL in PVC R=0.054
400 (all wires) in PVC XL=0.040

Ze (0.066) is not = R x pf x XL (0.054 x 0.85) +0.040=0.0859

Thank you

 

[jtester]

Derick

Remember that R and XL are 90 degrees out, you need the vector sum, not arithmetic. When I do that, I get ZE=.067

Hope that helps.

Jim T

 

[Derick]

Derick

Remember that R and XL are 90 degrees out, you need the vector sum, not arithmetic. When I do that, I get ZE=.067

Hope that helps.

Jim T

You got it Jim (1st line of Table 9 note 2)
Thank you ,sir

 

[bob]

Guys I have problem with understanding Table 9 and note #2

Ze=R x pf x XL

For example: 400 AL MCM in PVC Ze=0.066 from table 9

Based on formula above shouldn't the sum of 85%R and XL be the same as (0.066)? by taking values from XL and R

400 AL in PVC R=0.054
400 (all wires) in PVC XL=0.040

Ze (0.066) is not = R x pf x XL (0.054 x 0.85) +0.040=0.0859

Thank you

Z = sqrt( R? + X?)