Nanjing Huaju Electronics grandly launches the WMZ13A series PTC thermistors specifically for the smart meter market. The products include protection thermistors with communication interface RS232, protection thermistors with communication interface RS485, and primary coil overcurrent protection thermistors.

　　1. Application scope: WMZ13A series PTC thermistor is a protective element that automatically protects and recovers against abnormal temperatures and abnormal currents. It replaces traditional fuses and can be widely used for overcurrent in motors, transformers, electronic circuits, etc. Overload protection. The thermistor reduces the residual current value by limiting consumption in the entire line through sudden changes in its resistance value. In a traditional fuse line, it cannot recover by itself after it is blown, while a PTC thermistor can resume its protective function after the fault is removed.

　　To choose a PTC thermistor as an overload protection component, first confirm the maximum normal operating current of the line (that is, the non-operating current of the PTC thermistor) and the maximum ambient temperature of the PTC thermistor installation location (during normal operation ), and secondly, the protection Current (that is, the operating current of the PTC thermistor), maximum operating voltage, rated zero power resistance, and factors such as the overall size of the component should also be considered. As shown in the figure below: the relationship between the operating environment temperature, non-operating current and operating current.

　　2. Application scope: Mainly used for overcurrent, overload and short-circuit protection of smart meters, transformers, motors, switching power supplies, chargers, adapters, instruments, control panels, household appliances, air conditioners, microwave ovens, etc.

　　3. Application principle:

　　Connect the overcurrent protection PTC thermistor in series in the power circuit. When the circuit is in a normal state, the current flowing through the PTC is less than the rated current. The PTC is in normal state and has a very small resistance, which will not affect the electronic ballast (energy saving). Normal operation of protected circuits such as lamps, transformers, and multimeters. When the circuit current greatly exceeds the rated current, the PTC suddenly heats up and the resistance suddenly increases to a high resistance state, thereby limiting or blocking the current and protecting the circuit from damage. After the current returns to normal, the PTC also automatically returns to the low resistance state, and the circuit returns to normal operation.

　　Overcurrent protection PTC thermistors are used in overcurrent protection applications such as electronic ballasts (energy-saving lamps, transformers, multimeters). 3. Model name, appearance structure and dimensions:

Resistant to 220Vac, 380Vac 485 communication interface protection

485 protection circuit:

RS-232 protection circuit

CAN protection circuit

PTC generally chooses PTC thermistors of different voltage-resistant models according to the customer's need to prevent the voltage from incoming loops. TVS generally chooses a working voltage. The protection voltage must be less than the maximum withstand voltage of the protected device. Generally, TVS tubes with an operating voltage of 5V are used. A lightning protection circuit can be made by adding a corresponding discharge tube in front.

Main technical parameters:
Communication equipment switch overcurrent and overload protection

4-20mA small signal port protection

WMZ13A-06C (20Ω～32Ω) and WMZ13A-10C (20Ω～32Ω) are products specially launched for the design features of signal acquisition circuits in digital display instruments. In the signal sampling circuit of digital display instruments, the sampling resistance R is high. Precision chip resistors have high requirements on the use environment and are easily damaged in continuous overvoltage conditions, so they require special protection. Conventional protection circuits can choose two forward and reverse parallel switching diodes or bidirectional TVS tubes according to the size of the sampling resistance. This protection scheme only has a good protection effect on transient overvoltage. Abnormal sustained overvoltage can easily cause Damage to various port components. If a thermistor is connected in series to this circuit, the port can be efficiently protected under fault conditions, and the protection effect of the entire signal sampling circuit can be optimal.
2. Application circuit

PTC thermistor for primary overvoltage and overcurrent protection of transformer

The WMZ13A type PTC thermistor produced by Huaju Electronics is mainly installed in the power input end of microcomputer control boards of various household appliances, instruments and meters or in communication lines and communication equipment for overcurrent, overvoltage, overheating and lightning protection. This product is also called a 10,000-time fuse or a self-restoring fuse in electronic engineering. Due to its dual sensitivity to temperature and current, it makes up for the shortcomings of the temperature switch being insensitive to current and the conventional fuse being insensitive to temperature. It has the advantages of fast response, strong protection capability, and high reliability. It is a kind of Really high quality and low price protective components.