The VA150/3PN surge protector serves to prevent surge damage to equipment from inductive lightning products, an indispensable component for protecting electronic devices. As electronic products are increasingly integrated into everyday life, surge protectors are becoming more familiar. In reality, surge protection for electronic systems is still a relatively new field, and many issues surrounding surge protector selection and application remain controversial. This article explains the response time of surge protectors and the action sequence of multi-stage surge protectors.
Two, the operation sequence of multi-stage surge protectors
When a single-stage surge protector fails to suppress the侵入overvoltage to below the specified protection level, a surge protector with secondary, tertiary, or more stages of nonlinear suppression elements should be used.
Nonlinear componentsRv2AndRv2All are pressure-sensitive resistors, practical in use.RV1Gas discharge tubes, Rv2Also can be voltage regulator tubes or surge suppression diodes.TVSInsulator between the poles.ZsCan be an inductorLsOr resistorRsIfRV1AndRV2The conductive voltages are respectively:Un1AndUn2The components selected are alwaysUn2> Un1。
Someone believes that when the invasion shockwave is added toX-EAt the terminal, always first-class.RV1Lead copper, followed by the second grade. In fact, either first or second-grade lead-offs are possible, depending on the following factors:
(1) Intrusion shock wave waveform, primarily the speed of sound in the current wavefront.di/dt）；
(2) Nonlinear componentsRv1AndRV2Conduction VoltageUn1AndUn2Relative size;
(3) Isolation ImpedanceZsThe nature is whether resistive or inductive, and their sizes.
WhenZsFor resistanceRsAt times, it is most commonly a secondary pilot conduction. Following the secondary conduction, when the surge currentIAscendiRs＋Un2 ≥Un1It's only conductive at level one. After level one is conductive, due to the lower equivalent impedance of the next level under high current,RsThe equivalent impedance sum of the two stages is much smaller. Therefore, most of the surge current is discharged through the first stage, while the current discharged through the second stage is significantly lower. If the first stage is a gas discharge tube, the residual voltage after conduction is typically lower than the conduction voltage of the second stage.Un2Therefore, the secondary cutoff occurs, and the remaining surge current is discharged through the primary gas discharge tube.
IfZsFor inductanceLsAnd the rate of increase for the侵入 current at the beginning is quite rapid, under the given conditions.Ls(di/dt)＋Un2>Un1Satisfied,Then the primary conductor. If the limiting voltage during the primary conduction isUc1(1),Then, as the invasion surge current accelerates in the future.(di/dt)The decline, under the conditionsUC1(1) ≥Ls(di/dt)＋Un2When satisfied, the second level conducts. After the second level conducts, the output terminalYThe voltage is suppressed to a lower level.
