For the block diagram shown below : The characteristic equation is

• τl S (τps + 1) + Kc . Kp (τlS + 1) e-τd s = 0
• (τmS + 1) (τpS + 1) + Km . Kp e-τd S = 0
• τl S(τm S + 1) (τp S + 1) +Kc . Kp . Km (τl s + 1) e-τdS = 0
• (τms + 1) (τp s + 1) + Kc . Kp . Km . e-τdS = 0