Bench Talk

High reliability is paramount in our always on, hyper-connected world. Application downtime or failure runs the gamut from frustrating to incredibly expensive. That is why overvoltage protection remains a consistent requirement. Users expect seamless system operation so guarding them against unstable electrical service swells, switching, and lightning voltage transients just makes sense.

In the overvoltage protection component arsenal, Metal Oxide Varistors or MOVs are popular solutions. New MOVs boast high current handling, high current absorption, and fast reaction time to protect against transient faults up to their rated limits. Power supplies, power systems, line voltage, telecom systems, white goods, and appliances are among the applications using MOVs for protection. Unfortunately, they are susceptible to degradation and failure issues in certain harsh and uncontrolled environment applications. These problems are well-documented, and UL requires extensive testing to guard against harmful failure modes. An MOV failure can occur from a thermal runaway condition, which defines the lifespan of an MOV. Thermal runaway conditions could also increase the risk of fire in an MOV, prompting designs to typically require additional thermal cutoff or fusing devices for safety.

Understanding the reliability and safety issues of MOVs alone, Bourns took an innovative approach in engineering its new GMOV^™ overvoltage protection components. Developed as an enhanced protection solution, GMOV^™ devices help overcome degradation and catastrophic failure issues that could occur in discrete MOVs that are subjected to transient surges or temporary overvoltage exceeding their maximum rated values. The hybrid design combines Bourns^® patented, space-saving Gas Discharge Tube (GDT) with FLAT^® technology with an MOV. No additional board space is needed for this compact and enhanced overvoltage protector—it is a drop-in replacement for standard 14mm and 20mm MOVs.

Bourns^® GMOV^™ Overvoltage Protection Breakthrough Design

Why is this a breakthrough design? It uses the GDT to isolate the MOV from the line voltage, so it remains “on call but not on duty,” thereby shielding the device from transients and temporary overvoltage spikes that typically damage the MOV over time. By combining the two technologies, the GMOV^™ device also provides ultra-low leakage (<0.1µA), helping to reduce damage due to watt loss heating. The result of the combination is a higher reliability protection solution with virtually zero standby energy consumption.

And the design benefits don’t stop there. GMOV^™ components improve application reliability by delivering a predictable failure mode. This eliminates the need for indication circuitry and more expensive thermally protected MOV devices. Furthermore, GMOV^™ protectors help to eliminate the need for more costly and higher performance MOVs to meet UL 1449 lost neutral tests. Another way GMOV^™ devices offer a higher level of safety is that they are able to consistently blow fuses and breakers compared to MOVs alone, making them a superior solution for extended voltage threats.

The lower leakage current, reduced capacitance, and robust features of Bourns^® GMOV^™ devices deliver application advantages that other types of protection solutions cannot offer. In addition, GMOV^™ components are UL 1449 Type 5 recognized, saving engineering and qualification time.

For more information about the benefits Bourns^® GMOV^™ devices can provide, please see the Meeting Sustained Overvoltage Protection Requirements with a Hybrid Drop-In Replacement White Paper.