How to Improve TVS Surge Withstand Capability of Electronic Equipment with Electronic Protection Devices

How to Improve TVS Surge Withstand Capability of Electronic Equipment with Electronic Protection Devices

The issue of TVS Electromagnetic compatibility relates to the provisions on the maximum reliability protection of each power electronic equipment. There are certain relationships between electronic components or system components that must be prevented in advance to avoid interference. Electromagnetic compatibility is a relatively new regulation, which starts from ensuring the reliable and perfect operation of electronic equipment, especially military and aviation systems. With the development of electronics and the widely used microprocessors, Electromagnetic compatibility has begun to affect us. Experts from various countries have begun to study this issue and predict potential hazards to overcome negative impacts. The technical and economic impact of Electromagnetic compatibility cannot be measured by numbers, which is caused by various reasons.

TVS Surge is a sudden event that varies with time, location, and waveform. Not only should the parameters of surges be defined based on their causes (such as lightning strikes, startup and shutdown of large power grids, etc.), but the characteristics of transmission lines (such as resistance, terminal impedance, discharge capacity, insulation strength, etc.) are also very important conditions for defining surges. However, there are no identical two surge events. In the past decade, the current and voltage values in several different application environments have been standardized, making it possible to test equipment and engineering components under the same conditions. On the other hand, there may be fundamental numerical differences in practice.

Surges have potential hazards to all electronic devices and data systems. It is hidden, invisible, unpredictable, extremely dangerous, and the consequences are unimaginable. The actual amplitude of the surge is generally smaller than the lightning current, but the former may cause the same damage as the latter. By providing high, medium, and low level surge protection products, the company can effectively meet the needs of users. The module designed for lightning protection has a lower cost and can be easily installed in the main and distribution boxes. The lightning current suppressor designed for the power supply allows it to avoid direct lightning and damage caused by power lightning strikes. High quality rheostat can conduct lightning into Earthing system. There is also a set of applicable surge protection products available for low-level protection.

In the future, due to various reasons, surge protection products will become increasingly popular. That is to say, the increase in integration density is inevitably accompanied by a decrease in the critical load values of the components in the circuit (integrated circuits, transistors, diodes, resistors, etc.); Due to the use of advanced production machinery, it is necessary to increase the safety of the production process; In the application of electronic equipment, attention should be paid to the protection of outdoor equipment (such as equipment with intelligent sensors); Electromagnetic pulse hazard (NEMP) generated by nuclear explosion: this is only the inevitable secondary result of nuclear explosion, which can damage all electronic equipment.

A common protection method is to use overvoltage and surge protection devices in key parts of the circuit, allowing overvoltage and surge to bypass to the ground through the protection devices, thereby greatly reducing the transient voltage and surge amplitude of the circuit. Another focus after the establishment of surge protection schemes is the selection of surge protection devices.

Surge protection devices

1. Diode type protection (such as transient voltage suppression diode TVS) can be divided into Zener type unidirectional avalanche breakdown; Bidirectional silicon Varistor. Unidirectional TVS devices are mostly used for DC output protection; Bi-directional TVS suitable for AC circuits

2. Other protective elements, gas discharge s, cannot be used to protect low-voltage circuits

3. It belongs to oxide Varistor (such as ZnO Varistor), not applicable to IC circuit

Application of overvoltage and surge protection devices in the use of electronic products

1. For the selection of TVS , the rated maximum Pulsed power must be greater than the maximum instantaneous surge power in the circuit

2. The selection of gas discharge s should ensure that the impulse breakdown voltage of the discharge  is always lower than the impulse discharge voltage of the protected equipment

3. Selection of Varistor. For overload protection, the value of Varistor should be greater than the voltage value of the actual circuit