Thermal overload relay symbol
Also called Overload relay, OL, Motor overload
A relay that trips a motor starter when the motor current stays too high for too long. Its heater element sits in the motor circuit, and its contact in the control circuit.
ANSI / IEEE
IEC 60617What the thermal overload relay symbol means
A relay that trips a motor starter when the motor current stays too high for too long. Its heater element sits in the motor circuit, and its contact in the control circuit.
ANSI and IEC symbols
Where you see it
Motor protection in direct-on-line and star-delta starters.
What is written next to it
On a schematic, the thermal overload relay usually carries its designator and setting range, such as F2 9 to 13 A.
Related symbols
Frequently asked questions
What does the thermal overload relay symbol look like?
On ANSI drawings: A heater element drawn as a loop, marked OL. In IEC 60617: A rectangle with a stepped line through it for the thermal element.
Is the thermal overload relay symbol the same in IEC and ANSI?
No. A rectangle with a stepped line through it for the thermal element.
Where is a thermal overload relay used?
Motor protection in direct-on-line and star-delta starters.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016