What is the purpose of an interlock in control systems?

• A. To control machine speed
• B. To prevent unsafe startup or operation by requiring certain conditions to be met first
• C. To monitor electrical current only
• D. To serve as a manual override

Answer: (B)

Interlocks function as safety gates in control systems. They prevent unsafe startup or operation by requiring certain conditions to be met before power is applied or the process is allowed to continue. In practice this means you might need a door to be closed, a valve in a safe position, a pressure or temperature limit to be within range, or an enabling signal from another safety device. If any prerequisite isn’t satisfied, the interlock blocks the start or halts the sequence, protecting people and equipment from harm. This safety gating is distinct from simply controlling speed, monitoring electrical current, or serving as a manual override, which are different roles within a control system. So the purpose is to ensure unsafe conditions cannot be reached by requiring the right conditions to be present before operation proceeds.