The most salient feature of 8AMC series thermal overload relay / motor thermal protection switch is large volume and large current carrying capacity. It is mainly used for capacitor-start motor, automobile motor, ballast, and transformer, etc. Protector with PTC heating system is reset manually.

Working principle
This thermal protective device is designed to be sensitive both to current and temperature. The heat generated from the rotation of motor, combined with the current thermal effect of the bimetal, contributes to a temperature rise that the bimetal can sensitively detect. Then the 2 contacts separate and the circuit is open. When the temperature cools down to the prescribed reset value, the bimetal flips again and makes the circuit closed.

Thermal protector drawings

1. Lead wire; 2.Sealing glue; 3. Metal case; 4.Fixed base; 5.Conducting strip; 6. Plate; 7. Bimetal disc; 8. Stationary contact; 9. Movable contact; 10. Bracket

Characteristics
1. Contact capacity: 250VAC/25A; 125VAC/50A; 80A/24VDC
2. Trip time: upon your request
3. Contact resistance: ≤100mΩ (measured with ohmmeter at 25 °C)
4. Lead wire: UL3321 AWG #18 or #16, black; custom-designed cable is also available
5. Pulling Strength of lead wire: 50 N applied from lead to lead for 1 minute. No slip-off or rupture
6. Insulation resistance: the resistance between the terminal and plastic case is over100 MΩ (measured with 500 VDC at 25 °C)

Rated Opening & Reset Temperature

Index
Induction Motor Thermal Switch, Thermal Protector
Capacitor Start Motor Protector, Transformer Thermal Switch
Car Motor Thermal Protector