Unsa ang mosabot sa sulod sa surge protector samtang may lightning strike?
Unsa ang Mga Nangyari Sa Loob sa Surge Protective Device Durante sa Lightning Strike?
Durante sa lightning strike, ang surge protective devices (SPDs) naghunahuna og importante nga papel sa pagprotekta sa mga electrical equipment gikan sa transient overvoltages (i.e., surges). Sumala aning mga main processes ug mechanisms nga nahitabo sa loob sa SPD durante sa mga event niini:
1. Surge Detection ug Response
Kung adunay surge gikan sa lightning strike nga mag-enter sa power system, ang surge protective device dili na maligo mahimong mohatag og detection sa abnormal voltage. Kasagaran, ang SPDs adunay set nga threshold voltage; kon ang detected voltage moboog sa threshold, ang protector mag-activate sa iyang protection mechanism.
2. Energy Absorption ug Dissipation
Ang SPDs absorb ug dissipate ang surge energy aron maprotektahan ang connected electrical equipment. Ang common absorption ug dissipation mechanisms mao kini:
a. Metal Oxide Varistors (MOVs)
Working Principle: Ang MOVs mao ang nonlinear resistive materials nga ang resistance mabago basehan sa applied voltage. Sa normal operating voltages, ang MOVs adunay high resistance; kon ang voltage moboog sa certain threshold, ang ilang resistance mogamay, allowing current to pass through.
Energy Dissipation: Ang MOVs convert excess electrical energy into heat ug dissipate it. Kon bag-o lang ang MOVs adunay self-recovery characteristics ug mahimo molabay pagkatapos sa multiple small surges, sila mahimo moguba kon adunay large or frequent surges.
b. Gas Discharge Tubes (GDTs)
Working Principle: Ang GDTs mao ang sealed tubes nga adunay inert gas. Kon ang voltage sa duha ka ends moboog sa certain value, ang gas sa sulod ionizes, creating a conductive path for current.
Energy Dissipation: Ang GDTs dissipate surge energy through the plasma created by gas ionization ug automatically extinguish the plasma once the voltage returns to normal, restoring insulation.
c. Transient Voltage Suppression (TVS) Diodes
Working Principle: Ang TVS diodes remain in a high-resistance state sa normal operating voltages. Kon ang voltage moboog sa ilang breakdown voltage, ang diode rapidly switches to a low-resistance state, allowing current to flow.
Energy Dissipation: Ang TVS diodes dissipate surge energy through the avalanche effect within their internal PN junctions ug suitable for fast-response small surges.
3. Energy Diversion ug Grounding
Ang SPDs dili lang absorb surge energy pero usab divert some of it to ground lines aron mas gamay ang impact sa equipment. Specific mechanisms include:
Diversion Circuits: Ang SPDs designed with specialized diversion circuits to guide overvoltage to the ground line, preventing it from directly entering load devices.
Grounding System: Ang maayo nga grounding system key to ensuring effective SPD operation. The grounding system should provide a low-impedance path to quickly dissipate surge energy into the earth.
4. Post-Surge Recovery
Pagkahuman sa surge event, ang SPD needs to return to its normal operating state. Different types of protectors have different recovery mechanisms:
MOVs: Kon ang surge dili moboog sa permanent damage sa MOV, it will automatically return to a high-resistance state once the voltage normalizes.
GDTs: Pagbalik sa normal voltage, ang plasma inside the GDT automatically extinguishes, restoring the insulating state.
TVS Diodes: Pagbalik sa normal voltage, ang TVS diodes also automatically return to a high-resistance state.
5. Failure Modes ug Protection
Kon bag-o ang SPDs designed to handle surges, sila mahimo moguba sa extreme cases. To ensure safety, many SPDs include additional features:
Thermal Disconnect Devices: Kon ang MOV or other component overheats ug fails, ang thermal disconnect device will break the circuit to prevent fires ug other hazards.
Indicator Lights/Alarms: Some SPDs equipped with indicator lights or alarms to notify users if the protector is still functioning correctly.
Conclusion
Durante sa lightning strike, ang surge protective devices protekta ang electrical equipment through the following steps:
Surge Detection: Identify situations where voltage exceeds normal ranges.
Absorption ug Dissipation of Energy: Utilize components like MOVs, GDTs, ug TVS diodes to convert surge energy into heat or other forms of energy.
Diversion to Ground Lines: Guide overvoltage to ground lines to minimize impact on equipment.
Return to Normal State: After the surge, the protector returns to its normal operating state.
Fault Protection: Provide additional safety measures in extreme cases to prevent further damage.
