Thermal Overload Relays
A thermal overload relay is an overload relay whose bimetal elements, heated by the motor current, detect a long-term overload above the set value and stop the motor by opening the contactor coil circuit with its auxiliary contact. It is used with a contactor on motor feeders to protect pump, fan and compressor motors against overheating caused by overload and jamming. The category includes Siemens 3RU2, Schneider Electric TeSys LRD and EasyPact TVS LRE, ABB TF series thermal overload relays, and ABB EF and Schneider Electric LR97D electronic overload relays; setting ranges such as 0.28-0.4 A, 7-10 A, 11-16 A and 80-104 A, frame sizes S00, S0, S2 and S3, and screw and spring connection types are available. Choose the setting range so that it covers the rated current on the motor label, the frame size according to the contactor it will work with, the trip class (for example Class 10A) according to the starting time, and the mounting style (directly on the contactor or on a rail) according to the panel. A thermal overload relay does not interrupt short-circuit current and does not open the power circuit itself; it does not replace a fuse or a motor protection circuit breaker.
Products
- Siemens 3RU2116-1FB0 Thermal Overload Relay 3.5-5 A — Siemens · SKU: 3RU2116-1FB0 · TRY 1,051.68 · Made to order
- Siemens 3RU2116-0GC0 Thermal Overload Relay 0.45-0.63 A — Siemens · SKU: 3RU2116-0GC0 · TRY 3,756.00 · Made to order
- Schneider LRD10 TeSys D Thermal Overload Relays 4...6A Class 10A — Schneider Electric · SKU: LRD10 · TRY 1,224.14 · In stock
- Siemens 3RU2116-1HC0 Thermal Overload Relay 5.5-8 A — Siemens · SKU: 3RU2116-1HC0 · TRY 3,756.00 · Made to order
- Siemens 3RU2126-4AC0 Thermal Overload Relay 11-16 A — Siemens · SKU: 3RU2126-4AC0 · TRY 4,456.00 · Made to order
- Schneider LRD05 TeSys D Thermal Overload Relays 0.63...1A Class 10A — Schneider Electric · SKU: LRD05 · TRY 1,224.14 · In stock
- Schneider LRD22 TeSys D Thermal Overload Relays 16...24A Class 10A — Schneider Electric · SKU: LRD22 · TRY 1,249.21 · In stock
- Siemens 3MU7210-1AA0 Thermal Overload Relay 23 - 32A — Siemens · SKU: 3MU7210-1AA0 · TRY 2,309.06 · In stock
- Schneider LR2K0316 TeSys K Differential Thermal Overload Relays 8...11.5A Class 10A — Schneider Electric · SKU: LR2K0316 · TRY 1,356.36 · In stock
- Siemens 3RU2116-1AB0 Thermal Overload Relay 1.1-1.6 A — Siemens · SKU: 3RU2116-1AB0 · TRY 1,051.68 · In stock
- Siemens 3RU2116-1FC0 Thermal Overload Relay 3.5-5 A — Siemens · SKU: 3RU2116-1FC0 · TRY 3,756.00 · Made to order
- Siemens 3MU7110-0QA0 Thermal Overload Relay 17 - 25A — Siemens · SKU: 3MU7110-0QA0 · TRY 1,506.75 · In stock
- Siemens 3RU2116-1DB1 Thermal Overload Relay - With Stop and Test Buttons 2.2-3.2 A — Siemens · SKU: 3RU2116-1DB1 · TRY 1,229.48 · In stock
- Siemens 3RU2146-4MB0 Thermal Overload Relay 80-100 A — Siemens · SKU: 3RU2146-4MB0 · TRY 4,555.32 · Made to order
- Schneider LRD14 TeSys D Thermal Overload Relays 7...10A Class 10A — Schneider Electric · SKU: LRD14 · TRY 1,224.14 · In stock
- Siemens 3RU2116-1DB0 Thermal Overload Relay - With Stop and Test Buttons 2.2-3.2 A — Siemens · SKU: 3RU2116-1DB0 · TRY 1,051.68 · In stock
- Siemens 3MU7310-2AA0 Thermal Overload Relay 23 - 32A — Siemens · SKU: 3MU7310-2AA0 · TRY 2,704.93 · In stock
- Siemens 3RU2116-1HB0 Thermal Overload Relay 5.5-8 A — Siemens · SKU: 3RU2116-1HB0 · TRY 1,051.68 · Made to order
- Schneider LR2K0310 TeSys K Differential Thermal Overload Relays 2.6...3.7A Class 10A — Schneider Electric · SKU: LR2K0310 · TRY 1,356.36 · In stock
- Schneider LRD21 TeSys D Thermal Overload Relays 12...18A Class 10A — Schneider Electric · SKU: LRD21 · TRY 1,249.21 · In stock
- Siemens 3RU2126-1KB0 Thermal Overload Relay 9-12.5 A — Siemens · SKU: 3RU2126-1KB0 · TRY 1,215.48 · Made to order
- Siemens 3RU2126-1JC0 Thermal Overload Relay 7-10 A — Siemens · SKU: 3RU2126-1JC0 · TRY 4,161.00 · Made to order
- Siemens 3RU2116-0FC0 Thermal Overload Relay 0.35-0.5 A — Siemens · SKU: 3RU2116-0FC0 · TRY 3,590.00 · Made to order
- Siemens 3RU2116-0JC0 Thermal Overload Relay 0.7-1 A — Siemens · SKU: 3RU2116-0JC0 · TRY 3,756.00 · Made to order
- Siemens 3RU2116-4AC0 Thermal Overload Relay 11-16 A — Siemens · SKU: 3RU2116-4AC0 · TRY 3,756.00 · Made to order
How to choose Thermal Overload Relays
A thermal overload relay is an overload relay whose bimetal elements, heated by the motor current, detect a long-term overload above the set value and stop the motor by opening the contactor coil circuit with its auxiliary contact. It is used with a contactor on motor feeders to protect pump, fan and compressor motors against overheating caused by overload and jamming.
- Separate overcurrent/leakage protection, motor starting and local isolation requirements.
- Select rated current, pole count and breaking capacity (kA) from the installation calculation.
- Match coil voltage, auxiliary contacts and tripping curve to the control circuit and load type.
Frequently asked questions
What is Thermal Overload Relays and where is it used?
A thermal overload relay is an overload relay whose bimetal elements, heated by the motor current, detect a long-term overload above the set value and stop the motor by opening the contactor coil circuit with its auxiliary contact. It is used with a contactor on motor feeders to protect pump, fan and compressor motors against overheating caused by overload and jamming.
What should I compare when choosing Thermal Overload Relays?
Choose the setting range so that it covers the rated current on the motor label, the frame size according to the contactor it will work with, the trip class (for example Class 10A) according to the starting time, and the mounting style (directly on the contactor or on a rail) according to the panel.
Where can I find technical details for Thermal Overload Relays products?
A thermal overload relay does not interrupt short-circuit current and does not open the power circuit itself; it does not replace a fuse or a motor protection circuit breaker.