Nanjing Huaju Electronics grandly launches the composite PTC thermistor WMZ13A series composite PTC thermistor with dual protection functions of overvoltage and overcurrent protection. Huaju Electronics creatively combines the PTC thermistor with overcurrent protection function and the overvoltage protection function. The protective varistor is packaged into a device so that they are coupled to each other to have both overcurrent protection and overvoltage protection. These products have been widely used in smart instruments, high-performance small switching power supplies, and LED lighting, producing good economic and social benefits.

　　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 and overvoltage 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 electronic equipment and other devices. Protect the normal operation of the circuit. 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. Similarly, when the external voltage fluctuates, the varistor plays an overvoltage protection function. The increase in current flowing through the PTC thermistor can also cause the PTC to suddenly heat up, and the resistance value suddenly increases to a high resistance state, thereby limiting or blocking the current and protecting the voltage. The PTC thermistor with overcurrent and overvoltage protection has a wide range of applications in instrumentation.

　　3. Model name, appearance structure and dimensions:

　　Composite PTC thermistor for small power switching power supply to prevent overvoltage

　　In order to thank many power meter users for their strong support and help to our company's products over the years, our company launched a composite PTC thermistor in early 2007. This product is an important product of our company. Since its launch on the market, it has solved many problems that power meter companies have been troubled by, and has received strong support from most merchants!

In addition, WMZ13A can also be used for lightning protection and overcurrent and overvoltage protection. Or overvoltage and overcurrent protection for other electronic equipment.

Application of WMZ13A composite PTC thermistor in the protection of LED drive power supply:

The WMZ13A series composite PTC thermistor can be used to solve the protection problems of overvoltage, overheating and overcurrent encountered by low-power LED driving power supplies. It is the preferred overvoltage protection solution in the design of many LED drive power supply manufacturers. However, due to the fact that the varistor cannot pass a continuous large current and will gradually fail due to the reduction of the varistor voltage during the response process, the failure rate of the varistor during use is still high. Designers have to gradually increase and increase the size and varistor voltage parameters of the varistor, but the high residual voltage drop after increasing the varistor voltage will have an adverse effect on the circuit. Secondly, as a power surge suppressor, the NTC thermistor only protects the switching tube and electrolytic capacitor from impact when the switching power supply is powered on. Due to its low resistance during normal operation, it is powerless to affect line pulses and operating surges. In particular, switching operations with short intervals are fatal to switching power supplies that use NTC for surge suppression. In addition, the fuse used in the primary part of the switching power supply often melts due to the pressure-sensitive response during transient overvoltage, causing unnecessary maintenance. When using a PTC thermistor as a resettable fuse, since the rated operating current of the PTC thermistor is closely related to the ambient temperature, in order to take into account the operating current of the PTC thermistor at the lowest operating voltage and the highest ambient temperature, the PTC thermistor is The resistor is slow or does not protect against overvoltage in normal or low temperature environments. This increases the probability of failure of the LED drive power supply's downstream circuit. Due to the above reasons, we have developed an appropriate composite PTC thermistor, which does not need to consider the impact of lower ambient temperature on the response speed, and can appropriately reduce the impact of surge voltage and group pulse on the LED drive power supply. When an unexpected overvoltage occurs, the nS level responds immediately in a short time, clamping the power supply voltage within the residual voltage range of the varistor. The power supply operates normally and returns to the original working state after the overvoltage is reduced. Specifically, a PTC thermistor and a varistor are packaged together, and the current and temperature generated when the varistor is over-voltage are used to make the thermistor respond quickly, and the impact of the rise in the resistance of the thermistor on the voltage and current is reflected. Come to protect the varistor. Due to the comprehensive protection effect of current and voltage between the thermistor and varistor, without worrying about damage to the varistor, in the design of this composite PTC thermistor, we have The rated operating current of the varistor and thermistor is also boldly designed: the rated operating current of the product is designed to be as large as possible while ensuring the protection effect. In order to verify the long-term working reliability of the composite PTC thermistor. After a long period of time on the high-voltage aging life test bench, our company powered on the 450V high voltage for 1 minute and cut off the power for 5 minutes. Among the 200 samples, the thermistor and varistor were intact.

The following products have the characteristics of small steady-state resistance, low rated current, high voltage resistance, and fast response speed. They are economical and applicable choices for realizing 485 communication interface protection. Since its launch on the market, it has received a good response from the market.

Resistant to 220Vac, 380Vac 485 communication interface protection

PTC thermistor for primary overvoltage and overcurrent protection of transformer

华巨电子 生产的WMZ13A型PTC热敏电阻器，主要装配在各种家用电器、仪器、仪表的微电脑控制板电源输入端或通讯线路、通讯设备中作过流过压过热防雷击保护。该产品在电子工程上又叫万次保险丝或自恢复保险丝。由于其对温度和电流的双重敏感性，使其弥补了温度开关对电流不敏感、常规保险丝对温度不敏感的缺点，使其具有响应速度快、保护能力强、可靠性高等优点，是一种真正质优价廉的保护元件。