Fast Response 5D 511k Zinc Oxide Varistor High Peak Current Withstand Capability

OEM Fast Response 5D 511k Metal Oxide Varistor High Peak Current Withstand Capability​

The most common modern type of varistor is the metal oxide varistor (MOV). Ceramic blocks of this type containing particles of zinc oxide, in a matrix of other metal oxides, such as small amounts of bismuth, cobalt, manganese oxides, are sandwiched between two metal plates to form the electrodes of the device. The boundaries between each die and adjacent elements form diode junctions, which allow current to flow in only one direction. The accumulation of randomly oriented grains is electrically equivalent to a network of back-to-back diode pairs, each in parallel with many other pairs.

When a small voltage is applied across the electrodes, only the reverse leakage through the diode junction causes a tiny current to flow. When a large voltage is applied, the diode junction breaks down due to a combination of thermionic emission and electron tunneling, causing a large current to flow. The result of this behavior is a nonlinear current-voltage characteristic, where MOVs have high resistance at low voltages and low resistance at high voltages.

Electrical characteristics

Varistors remain non-conductive during normal operation. As a shunt mode device, varistors are often used to suppress line voltage surges when the voltage across them remains well below their "clamping voltage". Varistors can fail for two reasons.

Catastrophic failures have occurred due to unsuccessful attempts to limit very large surges caused by events such as lightning strikes, where the energy involved is many orders of magnitude higher than the varistor can handle. Subsequent current flow from the impact could melt, burn or even vaporize the varistor. This thermal runaway is due to the lack of uniformity at the junctions of individual grain boundaries, leading to the failure of the dominant current path under thermal stress when the energy in the transient pulse (usually measured in Joules) is too high (i.e. significantly exceeds the fabrication quotient of the "Absolute Maximum Ratings"). The potential for catastrophic failure can be reduced by overrating or using specially selected MOVs in parallel.

Cumulative degradation occurs as more surges occur. For historical reasons, many MOVs have been misspecified, allowing frequent inflation that also reduces capacity. In this case, the varistor is not visibly damaged and outwardly appears to be functioning (no catastrophic failure), but it no longer provides protection. Eventually, it goes into a short circuit as the energy discharge creates a conductive path through the oxide.

The main parameter affecting the lifetime of a varistor is its energy (joule) rating. Increasing the energy level increases the number (of a defined maximum size) of transient pulses it can accommodate exponentially as well as the cumulative energy sum from clamped smaller pulses. When these pulses occur, the "clamping voltage" it provides during each event decreases, and a varistor is generally considered functionally degraded when its "clamping voltage" changes by 10%. Manufacturer's life expectancy charts involve current, severity, and number of transients for failure prediction based on the total energy dissipated over the life of the part.

In consumer electronics, especially surge protectors, the MOV varistors used are small enough that they will eventually fail. Other applications, such as power transmission, use VDRs of different structures in multiple configurations, designed for long life.

Characteristics of varistors

(1) Advantages: the voltage range is very wide, from several volts to several thousand volts, the surge current can be from tens to several thousand amperes, the response speed is fast, there is no polarity, no freewheeling, and the peak current withstand capacity is large. low price.
(2) Disadvantages: The clamping voltage is relatively high, which can generally reach 2 to 3 times the working voltage. In addition, pressure
The leakage current of the varistor increases with the increase of the number of surge impacts. The response time is longer and the parasitic capacitance is larger.
(3) Applicable occasions: DC power lines, low-frequency signal lines, or used in series with gas discharge tubes for AC power lines.

Specifications:

Dongguan Chenglue Electronics Co., Ltd. Number of employees: 152 employees. The company mainly produces and sells: X2 safety capacitors, CBB21/22, metallized film capacitors, Y1/Y2 safety capacitors, varistors. The price is 6%-8% lower than that of peer factories. CBB21/2 capacitors, film suppliers Qingdao Chengwen, Zhongshan Dongli, Quanzhou Jiadeli, all products are sprayed with tin-zinc 4/6 alloy, the products used are stable in operation under high temperature and high pressure conditions of 105 degrees, low loss and long service life.

Conventional products are equipped with 50K-100KPCS safety stock, large-volume conventional capacitors, and the delivery time is 3-5 days for batch delivery. Chenglue factory has a production scale of 20 Dewei winding machines, and the daily production of film capacitors is 300-500KPCS.

Products are widely used in LED power supply, power adapter, switching power supply, home appliance control board, lighting appliances, automotive electronics, chargers, motors, igniters and other electronic products. The product X2/Y safety capacitors have passed the United States (UL), Germany ( VDE), China (CQC), South Korea (KC) and other countries and regions product safety certification, product environmental protection has passed the requirements of ROHS, RECAH, halogen-free and other directives.

Since the establishment of the company, relying on advanced production equipment, continuous improvement of enterprise management mode, scientific and technological talents and well-trained workforce, we have strived to make Chenglue Electronics a supplier of electronic components for internationally renowned brands and well-known manufacturers. The company sincerely develops the market with the concept of "seeking reputation with quality, seeking development with reputation, and creating value for customers", and serves customers with the service concept of "customer needs are our work goals"



Company advantage

Complete testing equipment and production line​



At present, it has passed the in-depth inspection of SGS institutions, ISO9001: 2015 environmental management system, and other quality management system certifications​



To provide customers with professional customized services, according to different requirements of customers to develop, design, produce products that meet various special needs. Professional application engineers, door-to-door assistance in model selection, and free technical support for customers. Provide customers with professional customized services ,According to the different requirements of customers, we develop, design and produce products that meet various special needs. Professional application engineers come to assist in model selection and provide technical support for customers free of charge. Provide customers with professional customized services and develop products according to different requirements of customers. , design, and produce products that meet various special needs. Professional application engineers, on-site assistance in model selection, free technical support for customers, professional customized services for customers, research and development, design, and production that meet various requirements according to different requirements of customers. Professional application engineers for products with special needs, door-to-door assistance in model selection, and free technical support for customers. Provide customers with professional customization services, develop, design, and produce products that meet various special needs according to different requirements of customers. Professional application Engineers, door-to-door assistance in model selection, and free technical support for customers. Provide customers with professional customization services, develop, design, and produce products that meet various special needs according to different requirements of customers. Professional application engineers, door-to-door assistance in model selection, Provide technical support to customers free of charge

Our product range：

X2 Safety Capacitor
Y1 Safety Capacitor
Y2 Safety Capacitor
Metallized Polypropylene Film Capacitor
Super Capacitor
Metallized Polyester Film Capacitor
MMKP82 Capacitor
Aluminum Electrolytic Capacitor
Metal Oxide Varistor
SMD MOV Varistor
NTC Thermal Resistor
NTC Temperature Sensor
Hall Effect Current Sensor
Electric Vehicle Fuse
Gas Discharge Tube