Motor Starting PTC Thermistor Application Principle 1

Application Principle

During startup, the motor must overcome its own inertia and the counteracting force of the load (such as the refrigerant's resistance when a refrigerator compressor starts). Therefore, the motor requires high current and torque at startup. Once normal operation is achieved, energy efficiency demands a significant reduction in required torque. By adding an auxiliary winding that operates only during startup and disconnects afterward, this can be accomplished. Connecting a PTC thermistor in series with the start auxiliary winding ensures the PTC thermistor enters a high-resistance state after startup, effectively cutting off the auxiliary winding and achieving the desired effect.

Electronic ballast, energy-saving lamp preheating soft start PTC thermistor

external structure

Application Principle

By applying a PTC thermistor to the electronic ballast of energy-saving lamps, the product can be directly connected across the resonant capacitor of the lamp tube without modifying the circuit. This changes the hard start of the electronic ballast and electronic energy-saving lamps to a preheating start, with a filament preheating time of 0.4-2.0 seconds, extending the lamp tube's lifespan by more than fourfold.

The preheating startup using PTC thermistors is as follows: When the switch is first turned on, Rt is at room temperature, and its resistance is much lower than that of C2. Current flows through C1 and Rt to form a circuit for preheating the filament. After approximately 0.4-2 seconds, the Joule heating of Rt exceeds the Curie temperature Tc, causing it to jump into a high-resistance state. Its resistance becomes much higher than the impedance of C2, and current flows through C1 and C2 to form a circuit, leading to L resonance and generating high voltage to illuminate the lamp