When it comes to protecting electric motors from overheating, choosing a reliable thermal protector is crucial. Thermal protectors prevent damage caused by excessive heat, ensuring that motors operate efficiently and have a longer lifespan. Saftty, a leading manufacturer of high-quality thermal protectors, offers a wide range of solutions designed for various motor applications. 

Why Thermal Protection Matters for Motors

Electric motors generate heat during operation, and in many cases, environmental factors or motor overloads can lead to overheating. If not managed properly, this excessive heat can cause motor failure, reducing efficiency and leading to costly repairs or replacements. Thermal protectors act as a safeguard by detecting high temperatures and automatically shutting down the motor to prevent further damage.

Key benefits of motor thermal protectors:

· Prevents overheating: Protects the motor from damage by cutting off power when temperatures exceed safe limits.

· Extends motor lifespan: Reduces wear and tear by maintaining safe operating conditions.

· Improves efficiency: Ensures that the motor runs at optimal performance without the risk of overheating.

Saftty Motor Thermal Protectors You Can Trust

1. Saftty ST01 Motor Thermal Protector

Main parts

1) Ceramic cover plate 2) stationary silver contact 3)  spring disc

4) movable contact 5) Conductive housing 6) bimetal disc

Construction

Stationary silver contact are riveted with ceramic cover plate. The movable contact are welded to the spring disc, which is in the shape of a cross, and the four feet are connected to the bottom of the housing. The inner hole of the bimetal disc is placed on the spring disc through the movable contact. The current pass through the stationary silver contact to the movable contact, and then connects the conductive housing through spring discs to form a loop.

Function

When the circuit is normal, the movable contact is in close contact with the stationary silver contact under the pre-pressure of the spring disc. When the rated operating temperature is reached, the bimetal disc is deformed by heat, snaps into its inverted position and pushes the spring disc downwards. The contact is abruptly opened and the temperature rise of the device to be protected is disrupted.

After the circuit is disconnected, the ambient temperature begins to fall.  When it reaches the defined reset temperature, the bimetal disc and the spring disc snaps back into its start position,  the movable contact and the stationary  silver  contact  will  close  again, and the circuit returns to the conduction state.

2. Saftty ST06 Series Thermal Protector

Main parts

1) Ceramic cover plate  2) stationary silver contact  3) shaft pin

4) bimetal disc   5) spring disc  6) movable contact  7) housing

Construction

Stationary silver contact and ceramic covers are riveted together; The movable contact, bimetal disc and spring disc are riveted together by shaft pins. The movable contact is in close contact with the stationary silver contact under the pre-pressure of the spring disc; The current passes through the stationary silver contact and the movable contact to form a loop.

Function

When the circuit works normally, the movable contact and the stationary silver contact are in a closed state. When the rated operating temperature is reached, the bimetal disc is deformed by heat, and the spring disc is pushed downward through the riveting shaft pin, so that the movable and stationary silver contact are abruptly opened. After the circuit is disconnected, the ambient temperature begins to fall. When it reaches the defined reset temperature, the bimetal disc and the spring disc snaps back into its start position, the contacts will close again, and the circuit returns to the normal working state.

3. Saftty ST07 Thermal Protector

Main parts

1) Insulating paper  2) Conductive housing  3) bimetal disc

4) movable contact  5) stationary silver contact  6) base  7) iron nails

Construction

The stationary silver contact is welded on the base, the movable contact is welded to one end of the bimetal disc, the other end is welded to the housing by iron nails. The movable contact is in close contact with the stationary silver contact under the pre-pressure of the bimetal disc, the base and the housing are isolated by  insulating paper. The current first passes through the movable contacts connected to the housing and bimetal disc,  and then through the stationary silver contacts on the base to form a loop.

Function

When the circuit works normally,  the contact is in a closed state. When the rated operating temperature is reached, the bimetal disc is deformed by heat and snap rapidly, cut off the circuit. After that, the device begins to cool down. When it reaches the defined reset temperature, the bimetal disc and the spring disc snaps back into its start position, the contacts will close again, and the device starts working again.

4. Saftty ST08 Motor Thermal Protector

ST08 is a protector with double protection function of overcurrent and overtheating, and its built-in heating wire and bimetal form a series circuit. The overload current when the motor is blocked will make the heating wire heat up rapidly, which will heat the bimetal disc and accelerate the heating speed of it, so that the bimetal disc can reach the rated operating temperature faster and bounce open, cutting off the circuit. The heating wire with different resistance values has different heat generation, resulting in different trip times. By adjusting the resistance of the heating wire, it is possible to control the tripping speed of the protector when the current value is fixed.

5. Saftty ST09 Motor Thermal Protector

ST09 thermostat is a double-pole, double-throw, resettable or manual reset ultra-current (up to 250VAC 63A) temperature controller. The plastic structural parts isolate the bimetal disc that senses the temperature and the beryllium copper metal part that passes the current, preventing the thermal effect generated by the current from heating the bimetal disc, causing it to open in advance and improving the accuracy of the protection temperature.

6. Saftty ST10 Series Motor Protector

ST10 high-current thermal protector is a high-current protector with overcurrent, overheating double protection function, built-in heating plate and bimetal disc to form a series circuit. The overload current when the motor is blocked will make the heating wire heat up rapidly, which will heat the bimetal disc and accelerate the heating speed of it, so that the bimetal disc can reach the rated operating temperature faster and bounce open, cutting off the circuit.

7. Saftty BW-B Thermal Protector

Main parts

1) Shell  2) Iron bracket  3) bimetal disc

4) movable contact  5) Base  6) stationary silver contact

Construction

The movable contact are welded to the bimetal sheet and then welded to the iron bracket. The stationary silver contact and base are molded into a whole, and then the base is riveted with the iron bracket. The current first passes through the movable contact on the bimetal disc from the iron bracket, and then passes through the stationary silver contact to form a loop.

Function

Under normal conditions, the moving contact is in close contact with the stationary silver contact under the pre-pressure of the bimetal disc; When the rated operating temperature is reached, the bimetal disc is deformed by heat and snap rapidly, cut off the circuit. After that, the device begins to cool down. When it reaches the de-fined reset temperature, the bimetal disc and the spring disc snaps back into its start position, the contacts will close again, and the device starts working again.

8. Saftty BW-E Motor Protector

Main parts

1) Shell  2) Base  3) Bimetal disc  4) Movable contact

5) Temperature calibration plate  6) Static contacts

Construction

The movable contact are welded to the bimetal sheet and then wel-ded to the iron bracket. The stationary silver contact and base are molded into a whole, after the current passes through the temper-ature calibration plate and the bimetal disc, it forms a loop from the moving contact to the static contact.

Function

Under normal conditions,  the moving contact is in close contact with the stationary silver contact under the pre-pressure of the bimetal disc;  When the rated operating temperature is reached, the bimetal disc is deformed by heat and snap rapidly,  cut off the circuit. After that, the device begins to cool down. When it reaches the defined reset temperature, the bimetal disc and the spring disc snaps back into its start position, the contacts will close again, and the device starts working again.

9. Saftty ST11 Thermal Protector

Main parts

1) Iron cover plate 2) stationary silver contact 3) spring disc

4) movable contact 5) housing 6) bimetal disc 7) Insulating paper

Construction

Stationary silver contact are riveted with iron cover plate.; The bimetal disc and spring disc are combined by steps on the movable contact. The current passes through the stationary silver contact to the movable contact, and then connects the housing through the spring disc to form a loop.

Function

When the circuit is normal, the movable contact is in close contact with the stationary silver contact under the pre-pressure of the spring disc. When the rated operating temperature is reached, the bimetal disc is deformed by heat, snaps into its inverted position and pushes the spring disc downwards. The contact is abruptly opened and the temperature rise of the device to be protected is disrupted.After the circuit is disconnected, the ambient temperature begins to fall.  When it reaches the defined reset temperature, the bimetal disc and the spring disc snaps back into its start position, the contacts will close again, and the circuit returns to the conduction state.

Choosing the right motor thermal protector is essential for ensuring the long-term performance and safety of electric motors. Saftty’s wide range of thermal protectors, such as the ST01, ST06, ST07, and ST09 series, offer the reliability and precision needed for various motor applications, from consumer appliances to industrial machinery. These protectors not only prevent motor overheating but also improve efficiency, reduce maintenance costs, and extend the lifespan of the equipment.