PTC thermistors for motor starting

Starting-circuit with PTC Thermistor has more advantages than the previous heavy-hammer starting-circuit.-. No trigger or noise, free Switching, and Long Operating Life-. It can control the current without other controller. The small size can be connected directly to compressors for use-. Support most of the return circuits that compressors need-. Low Power Consumption-. High Stability Durability and Reliability-. Cheap for it’s many functions-. Quick and Powerful Starting.

Motor-starter is a machine that makes use of the PTC pottery current-time feature. When the voltage applied to PTCR, the heavy current begins to pass through, and after certain time, with temperature increasing of the PTCR, resistance value goes up sharply and cause current to fall down rapidly. During this time, ts can change from 0.1s to several seconds. The specific time depends on PTCR’s heating capacity, resistance value,heating dissipation condition, overloaded resistance and operating voltage. When the outer electricity voltage withdrawals, PTCR will become cool and alter to normal resistance. This principle of PTCR is used extensively in household refrigerator and air-conditioner motor-starter and so on. One point should be noticed that when using the delay-time feature of PTCR, we should make the PTCR recover to its original temperature in certain time tr(That is what we called recovering time). So sudden repeated movements should be avoided, otherwise PTCR cannot provide constant heavy current, and the compressor cannot start or work normally, which will cause the compressor burnt.
When the electric motor is being started, its inertia and counterforce of loading has to be overcame  (eg: Its counterforce must be overcame when refrigerator compressor starts), so starting the electric motor needs relatively heavy current and torque. When it runs normally, and the torque need has to be brought down to save energy. Give electric motor a circle assistant loop, and it works only when the motor starts and it will break up after the current goes regularly. This effect can be reached by connecting the PTC Thermistor in series in starting circle assistant loop and cutting off the circle assistant loop when PTCR enters the state of high resistance,which can reach the required effection.

PTC Thermistors for motor-starting are mainly used in the circuit of refrigerator and air-conditioner motor-starting, frequency conversion air-conditioner-starting, motor over-heating protection.