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Compact Thermal Protection for Motors and Power Electronics
The SEKI ST-22 is a compact automatic-reset bimetal thermal switch designed to protect electrical equipment from overheating. Using a precision snap-action bimetal mechanism, the switch opens the circuit when its calibrated temperature is reached and automatically reconnects once the device has cooled.
Its small footprint, reliable switching performance and sealed construction make it an excellent choice for motors, transformers, LED drivers, battery chargers, power supplies and many other industrial or commercial applications.
Key Features
✔ Quick Despatch Worldwide from the UK
✔ Precision snap-action bimetal mechanism
✔ Available in temperature ratings from 60°C to 100°C
✔ Compact, space-saving design
✔ Suitable for both AC and DC applications
✔ Supplied with 70 mm insulated lead wires
✔ Long operating life and reliable performance
✔ Manufactured to meet international safety standards
Typical Applications
The ST-22 is widely used to provide over-temperature protection in:
-
Electric motors
-
Power transformers
-
LED drivers
-
Power supplies
-
Battery chargers
-
Solenoids
-
Heating elements
-
Lighting equipment
-
Industrial control systems
-
OEM electronic products
How It Works
Inside the ST-22 is a calibrated bimetal disc that reacts to temperature changes. Under normal operating conditions the contacts are closed, allowing current to flow. When the pre-set temperature is reached, the disc rapidly changes shape, opening the contacts and interrupting the electrical circuit.
As the device cools below its reset temperature, the contacts automatically close, restoring normal operation without requiring manual intervention.
Technical Specifications
| Specification | Value |
|---|---|
| Switch Type | Automatic Reset Bimetal Thermal Switch |
| Operating Temperatures | 50°C to 150°C |
| Temperature Increments | 5°C |
| Contact Rating | 7A @ 250VAC |
| DC Rating | Up to 5A @ 24VDC (application dependent) |
| Reset Differential | Approximately 30°C (typical) |
| Housing Material | Epoxy-sealed PBT resin |
| Protection Rating | IP45/IP65 depending on installation and version |
| Standard Lead Length | 70 mm XLPE insulated leads |
| Mounting Option | Surface mounting clip available |
ST-22 Thermal Switch Dimensions

Package Includes
-
1 × SEKI ST-22 Automatic Reset Thermal Switch
ST-22 Thermal protection Approvals

- Regular price
- £3.75
Compact Thermal Protection for Motors and Power Electronics
The SEKI ST-22 is a compact automatic-reset bimetal thermal switch designed to protect electrical equipment from overheating. Using a precision snap-action bimetal mechanism, the switch opens the circuit when its calibrated temperature is reached and automatically reconnects once the device has cooled.
Its small footprint, reliable switching performance and sealed construction make it an excellent choice for motors, transformers, LED drivers, battery chargers, power supplies and many other industrial or commercial applications.
Key Features
✔ Quick Despatch Worldwide from the UK
✔ Precision snap-action bimetal mechanism
✔ Available in temperature ratings from 60°C to 100°C
✔ Compact, space-saving design
✔ Suitable for both AC and DC applications
✔ Supplied with 70 mm insulated lead wires
✔ Long operating life and reliable performance
✔ Manufactured to meet international safety standards
Typical Applications
The ST-22 is widely used to provide over-temperature protection in:
-
Electric motors
-
Power transformers
-
LED drivers
-
Power supplies
-
Battery chargers
-
Solenoids
-
Heating elements
-
Lighting equipment
-
Industrial control systems
-
OEM electronic products
How It Works
Inside the ST-22 is a calibrated bimetal disc that reacts to temperature changes. Under normal operating conditions the contacts are closed, allowing current to flow. When the pre-set temperature is reached, the disc rapidly changes shape, opening the contacts and interrupting the electrical circuit.
As the device cools below its reset temperature, the contacts automatically close, restoring normal operation without requiring manual intervention.
Technical Specifications
| Specification | Value |
|---|---|
| Switch Type | Automatic Reset Bimetal Thermal Switch |
| Operating Temperatures | 50°C to 150°C |
| Temperature Increments | 5°C |
| Contact Rating | 7A @ 250VAC |
| DC Rating | Up to 5A @ 24VDC (application dependent) |
| Reset Differential | Approximately 30°C (typical) |
| Housing Material | Epoxy-sealed PBT resin |
| Protection Rating | IP45/IP65 depending on installation and version |
| Standard Lead Length | 70 mm XLPE insulated leads |
| Mounting Option | Surface mounting clip available |
ST-22 Thermal Switch Dimensions

Package Includes
-
1 × SEKI ST-22 Automatic Reset Thermal Switch
ST-22 Thermal protection Approvals

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