The maximum phase shift that can be obtained by using a

The maximum phase shift that can be obtained by using a lead compensator with transfer function
G(s) = (1 + 0.15s)
(1 + 0.05s)

is equal to—

Given, G(s) =	(1 + 0·15s)	......…(i)
	(1 + 0·05s)

In phase lead compensation.

Given, G(s) =	V₀(s)	=	(1 + sT)	......…(ii)
	V_i(s)		(1 + sαT)

on comparing equations (i) and (ii), we have
T = 0·15
αT = 0·05
or
α = 0·05/0·15 = 1/3
Now,

sin φ_m =	1 – α
	1 + α

where, φ_m is the maximum phase shift angle
or

sin φ_m =	1 – (1/3)
	1 + (1/3)

or
sin φ_m = 2/4 = 1/2
or
φ_m = sin^–1 (1/2) = 30°
Hence alternative (B) is the correct choice.

G(s) =	(1 + 0.15s)
	(1 + 0.05s)