How to find the right Circuit Protection Products AI guide
Written by an AI model from its trained knowledge.
What the AI looks for in Circuit Protection Products
- Device type for the threat
- Use MOVs to clamp mains surges, GDTs for very high surge current on telecom, antenna or data lines, TVS diodes for fast clamping on low-voltage electronics, and PTC resettable fuses or NTC limiters for overcurrent or inrush. Each technology trades speed, clamping level, surge capacity and failure mode differently, and the wrong type either fails to protect or damages the circuit.
- Working voltage margin
- The device's maximum continuous operating voltage must sit above the highest normal line voltage, including tolerance and swells. A part rated too close to the line voltage conducts during normal operation, overheats and fails early.
- Surge current and waveform
- Compare surge capability on the same standard pulse, usually 8/20 µs for current, and size for the exposure (indoor branch circuit versus service entrance or outdoor line). Surge figures quoted on different waveforms are not comparable, and undersized parts degrade with each hit.
- Failure mode and backup protection
- Put a fuse or thermal disconnect in series with any shunt protector on a power line. MOVs and overloaded GDTs can fail short, and without backup they can overheat or catch fire.
- Capacitance on signal lines
- On high-speed data or RF lines, choose low-capacitance devices such as GDTs or low-capacitance TVS arrays over MOVs. MOV capacitance distorts fast signals.
Brands that matter
- Littelfuse: Broad range of MOVs, GDTs, TVS diodes, PolySwitch PTCs and fuses.
- Bourns: GDTs, MOVs, Multifuse PTCs and TVS diodes, strong in telecom protection.
- TDK (EPCOS): Established maker of varistors, GDTs and NTC/PTC thermistors.
- Eaton Bussmann: Fuses and circuit protection components for power applications.
- Vishay: Thermistors, varistors and TVS diodes.
What to avoid
- Unbranded assortment kits used for mains-voltage protection, since their datasheet values are often unverifiable.
- Shunt protectors on power lines without a series fuse or thermal cutoff.
- Picking a part only by package size or appearance instead of its voltage and surge specifications.
Questions
MOV, GDT or TVS diode: which one do I need?
MOVs are the usual choice for AC mains clamping. GDTs handle the largest surges with very low capacitance but switch more slowly. TVS diodes react fastest at low voltages. Layered designs often combine a GDT or MOV upstream with a TVS diode near the sensitive chip.