Automatic shoe cover machine, also known as electric shoe polisher, is a small device widely used in modern homes, hotels, factories, enterprises and institutions. It is mainly used to do automatic shoe-shoe work when people go in and out. It is composed of control circuit and mechanical transmission part. Among them, the mechanical transmission part is driven by a small motor to drive the roller with a brush to achieve the purpose of sassafras. The core is the small motor. In this transmission system mechanism, small motors are prone to overload or gambling due to mechanical lack of lubricants, bearing wear ores, rust, dust, and different strengths of people's feet. Heavy damage to motors and wires can even cause fire accidents. Therefore, overload protection and gambling protection circuits must be designed for the motor to ensure safe operation.
The traditional design mostly uses bimetallic thermostat for motor over-temperature protection. After the motor is overloaded or gambling, the current is very large, which makes its temperature rise rapidly. The bimetal thermostat disconnects the circuit when it senses high temperature. However, the bimetal thermostat will not maintain the disconnected state after the circuit is disconnected. After the circuit is disconnected, there is no current, the temperature of the motor gradually decreases, the thermostat will turn on the motor that has been turned, and the motor will cycle and continue to heat up. When the thermostat is protected again, this cycle action. If the user cleans foreign objects after the motor turns, or the motor suddenly runs during inspection, it may cause accidents such as personal injury. The bimetal thermostat is only for temperature, not for current. The large current after the motor gambles repeatedly appears, and the control circuit will be burned out. And now there are applications of aluminum wire or copper clad aluminum wire to wind the motor. Rise faster, maybe the thermostat has not been disconnected, and the coil of the motor has been burned out. For this reason, we recommend applying PPTC (positive temperature coefficient thermistor) for overload protection and stall protection of the motor. There are repeated motor start-ups that cause bad results or disasters, because PPTC devices can complete overcurrent protection and overtemperature protection at the same time, and will always maintain this state of protection until the power is turned off before returning to the original state. The use of PPTC devices for motor stall protection and overtemperature protection is a cost-effective protection scheme. PPTC devices play a dual role in high current and high temperature rise under fault conditions such as short circuit, overcurrent, overtemperature, and motor stall. In this way, it can change from a low-resistance state to a high-resistance state faster than the bimetal thermostat, which can limit the current of the motor in time and protect the motor and equipment system. And keep this kind of protection state all the time, only after the power is cut off PPTC device will return from the high resistance state to the low resistance state. Uninterruptible power PPTC will not recover, which can effectively avoid the potential and potential problems and safety hazards of the automatic shoe cover machine.