China Thermal Over Temp Protection Switch

KSD9700 / KSD301 / KSD302 / JUC-31F / S01 / S06 / 7AM / 17AM / YS11 thermostat is a common Bimetal temperature control protection switch, which adopts the working principle of overheating power-off of bimetallic strip.

China “3MP / 6AP/ 8AM /2AM / 3MP / 17AM+PTC over current & temp bimetallic protector” is a type of electrical safety device that combines a standard ” 3MP ” bimetallic thermal overload protector with a Positive Temperature Coefficient (PTC) thermistor, allowing it to both react to excessive current (overcurrent) and high temperatures, automatically cutting power and resetting once the issue is resolved; essentially acting as a resettable fuse with added temperature protection.

common Bimetal temperature control protection switch

Snap Disc Limit Switch KSD9700 Temperature Control

Thermal Over Temp Protection Switch

Key components and function:
•Bimetallic protector:
This is the primary overcurrent protection mechanism, consisting of a bimetallic disc that bends and breaks the circuit when too much current flows through it, causing excessive heat generation.

•PTC Thermistor (Positive Temperature Coefficient):
This component further enhances protection by significantly increasing its resistance when it reaches a preset temperature, further limiting current flow in case of overheating.

How it works:
1. 1. Normal Operation:
When current is within safe limits, both the bimetallic disc and PTC thermistor operate normally, allowing current to flow freely.
2. 2. Overcurrent Condition:
If the current exceeds a preset threshold, the bimetallic disc heats up and bends, interrupting the circuit.
3. 3. High Temperature Condition:
Simultaneously, the PTC thermistor also heats up due to high current, drastically increasing its resistance and further limiting current flow.
4. 4. Resetting:
Once the fault is removed and the components cool down, the bimetallic disc returns to its original shape, re-establishing the circuit, and the PTC thermistor resets to its low resistance state, ready to protect again.

17AM+PTC over current & temp bimetallic protector

17AM / 3MP bimetallic thermal overload protector with PTC

3MP / 6AP Limit Switch Motor over current – thermal protector

Applications:
• Motor Protection:
Commonly used in electric motors for appliances like washing machines, dryers, and vacuum cleaners to protect against overload situations.
• Power Supply Protection:
Can be integrated into power supplies to prevent damage from overcurrent or overheating events.

Important points to consider:
• Current Rating:
Each protector is designed for a specific current rating, which should be matched to the application.
• Trip Time:
The time it takes for the protector to trip depends on the overcurrent level and the design of the bimetallic disc.
• Temperature Rating:
The PTC thermistor has a specific temperature threshold at which it activates, ensuring protection against excessive heat.