IEEE C62.43.0-2017 pdf free download – IEEE Guide for Surge Protectors and Protective Circuits Used in Information and Communications Technology Circuits, Including Smart Grid Data Networks- Overview.
4. General theory of operation of protectors
4.1 Introduction Both nonlinear and lincar charscteristic components can be used in surge proltctive devices (SPDs) (synon- ymous with surge prolector) for sunge mitigation. In SPDs, the most commonly used components are of the nonlinear type. Nonlincar components have a set threshold level, beyond which the characteristie rapidly changes to provide a limiting function. Figure 1 shows the various types of surge mitigatio function and the surge type they mitigate against. The left side of the figure shows nonlinear functions and the right side shows linear atenuating functions. Some functions can used to mitigate common-mode and diferential-mode sunges, while others are limited to difer- ential-mode or common-mode sunges. Subeluses 4.2 and 4.3 give a brief explanation of the fgure blocks.
4.2 Nonlinear limiting
4.2.1 General These devices are used on electronie equipment where voltage and current sunges on the signal line can cause system malfunction or filure. The devices have two distinct states. In the quescet state. they are sstally transparent to the system, in the operated state, they provide voltage limiting, current liming, or both. The devices are operated or sl-riggered by the voltage or current surge and may also slf-resct to their quiesent Surge protectors may contain vlug-liting devices, which are onnected in prall with the terminals to be protected. They may also contain crrent-limiting devices in series with the temminals to be protected. Numerous combinations of series and prallel components can be contained in sunge protectors, and a com- prehensive characterization is too complex to describe completely in this guide.
Therefore, several examples of these combinations are given in 5.2 through 5.9 to describe these protectors and to illustrate how internal component interactions occur. This information is organized according to the six basic configurations defined in IEEE Std C62.36. (These configurations are ilustrated in Figure 11.) Some of the description and theory of operation discussed in Clause 4 is common to many or all of these various configurations. Nonlinear limiters have two types of characteristic: discontinuous (switching) and continuous (clamping), as shown in Figure 2 and Figure 3, together with their limiting action on surges. There are technology variants on the generic characteristic. In Figure 2, the gray line represents a GDT voltage-limiting characteristic. In Figure 3, the foldback characteristic applies only to voltage limiters, and the re-entrant characteristic applies only to current limiters.
4.2.2 Overvoltage limiting Voltage-limiting components draw ltte current until the voltage exceeds the predetermined threshold voltage of the component.
4.2.2.1 Discontinuous characteristic voltage limiting These components use solid-state materials or gases. Figure 2 shows the voltage/current (V-I) characteristics for a solid-state thyristor and a gas discharge tube (GDT). The V-I characteristic is not continuous but has a break or breaks where switching occurs (IEEE Std C62.31-2006 [B16] and IEEE Std C62.37-1996 [B19]).IEEE C62.43.0 pdf download.