Which symbol represents the overload relay in a schematic diagram?

• A. Overload Relay
• B. OLB
• C. OL
• D. Overcurrent Relay

Answer: (C)

In schematic diagrams, protective devices are shown with concise abbreviations. For motor overload protection, the device is labeled with the abbreviation OL, which stands for overload. This shorthand is used to mark the overload relay that trips when the motor overheats, providing the specific protection for the motor circuit.

The other labels aren’t standard for this symbol: OLB isn’t a common designation for the overload relay, and an overcurrent relay refers to a different protection function used in feeders, not the motor circuit’s overload protection. So the symbol OL is the one that denotes the overload relay in this context.