OL stands for which term in control systems?

• A. Open Loop
• B. Output Level
• C. Optical Link
• D. Overload

Answer: (D)

OL in control systems is typically used to indicate an overload condition. This means the signal or the device’s output is beyond what the instrument can handle or display, causing saturation or readings outside the valid range. When a sensor, meter, or controller output is pushed past its limits, you’ll often see OL instead of a numeric value, signaling you to check ranges, scaling, or actuator limits. This is different from open loop, which describes a control approach that doesn’t use feedback; OL here refers to a range/capacity issue. Optical Link and Output Level aren’t standard terms used to denote this condition.