With the advancement of technology, it has been seen that over voltages are a prevalent source of damage in industrial electronic systems. Over voltages can be induced by air discharges as well as the switching activities of the equipment. Depending on where the interference source is located, the transfer impedance can be high or low. Low transfer impedance occurs when interference is present in the same circuit as the electronic equipment. In the case of interference from an external source, however, impedance is higher. A Combination Wave Generator, also known as a Surge Generator, is used to simulate both of these circumstances. The main focus of this article will be on a Surge Generator, its characteristics, and the advantages of such a generator.
Combination Wave/Surge Generators are typically tabletop units that have a considerable amount of weight. Planes with connections to the ground are required for the proper usage of a transient generator safely in EM test situations. Larger coupling/decoupling networks are required for three-phase power line system testing, which significantly increases the system’s size. In order to achieve conducted immunity test standards, combination wave/surge generators are critical in their use.
A combination wave generator is basically an analogue lightning surge wave generator with great dependability, designed for lighting companies. It can be used for EMC (Electromagnetic Compatibility) Surge Immunity Testing. It can also be used to assess the impact current absorption capacity and anti-jamming capability of connected electronic components, as well as the overvoltage protector and electrical circuit. It gives an accurate and excellent basis for assessing each port of EUT that is subjected to transient overvoltage disturbance immunity. Surge Wave generators are intelligent, simple to use and reliable, which serve as its biggest advantages.
Testing and measurement methodologies of IEC 61000-4-5 Electromagnetic compatibility (EMC) specifies two types of combination wave generators for the surge immunity test. Depending on the type of port to be evaluated, each has its own set of applications. Test ports suitable for connection to outdoor symmetrical communication lines are tested with the 10/700μs combined wave generator. In all other circumstances, the 1.2/50μs combination wave generator is employed.
The goal of this standard is for output waveforms to meet criteria at the point of application to the EUT. Waveforms must be measured without the EUT attached because they are provided with open-circuit voltage and short-circuit current. This generator, as provided by LISUN, is designed to produce a surge with 1.2s open-circuit voltage front time, 50s open-circuit voltage duration, 8s short-circuit current front time and 20s short-circuit current duration.
The effective impedance of a combination wave generator is defined as the ratio of peak open-circuit output voltage to peak short-circuit current at the same output port. The ratio for this generator is defined as a 2Ω effective output impedance. The waveform of voltage and current when the generator output is connected to the EUT is a function of the EUT input impedance. This impedance may alter during surges to the equipment due to appropriate operation of installed protection mechanisms, or flash over or component breakage if protection devices are missing or inoperative. As a result, the load should be able to get the 1.2/50μs voltage and 8/20μs current waves from the same generator output.
It is pertinent to take into account the precautions pertaining to the surge wave generators as well. When the generator is under continuous use, it is important to take note of its heating to ensure that it does not over heat. As the DC output port normally has a high voltage, there is chance of electric shocks which is why it is important to be careful about them. Additionally, in case of instrument breakdown or failure, the power fuse should be checked for issues. However, if the problems still persist, manufacturer should be contacted to aid in the issue.