Correct Answer - Option 1 : Both statement I and statement II are true and statement II is the correct explanation of statement I.
The transportation delay transfer function is given by:
T(s) = e-st
Let, initially the transfer function is:
G1(s) = G(s)
Then,
|G1(ω)| = G & ∠ G1(ω) = ϕ1
Now, with transportation delay, New transfer function is given as:
G2(s) = G1(s) ⋅ T(s)
G2(s) = G(s) ⋅ e-st
Then,
|G2(ω)| = G & ∠ G2(ω) = ϕ1 – ωT
So, the bode magnitude plate is unaffected while the bode phase plot just shifts down by –ωT.
Hence, the statement I & II are correct and statement I is the correct explanation of statement II.