What is MOVGT Hybrid Overvoltage Protection Device?

1:59

0:00 - Intro of MOVs 0:34 - Intro of MOVGTs 0:42 - Premature-aging-prevention MOVGTs 1:08 - Protection-enhanced MOVGTs 1:38 - Certification & Package & Operating voltage ratings Metal oxide varistors, or MOVs, are a commonly used overvoltage protection device that are placed in parallel with the load. Under normal operation, MOVs have a high resistance, but during high voltage transients they quickly change to a low resistance state and being conducting current to clamp the voltage to a safe level to prevent damage to the system. However, MOV performance degrades with each transient event, and many systems experience small transients that don’t require protection but do prematurely age the MOV, leading to early failure. Eaton Bussmann series MOVGTs are hybrid devices combining a GDT in series with an MOV to prevent premature aging and enhanced protection and can be used as a drop-in replacement for basic MOVs. With the MOVGT, the GDT isolates the MOV from small transients that are negligible to the overall system due to their short duration and low energy. This prevents unnecessary and premature aging of the MOV without exposing the system to damaging overvoltage. When a large transient occurs, the GDT activates and allows the MOV to clamp the voltage, providing the necessary protection to prevent damage to the system. The hybrid architecture of the MOVGT also provides enhanced protection. Where a typical 20 millimeter MOV can only withstand three 5000 amp 8 by 20 microsecond surge events, a 20 millimeter MOVGT can withstand 20 of these events as well as forty 10 kilovolt and 5000 amp surge events. Eaton’s Bussmann series MOVGTs are UL certified devices offered in radial leaded packages with disc sizes from 7 to 20 millimeters and recommended maximum continuous operating voltage ratings from 55 to 560 volts.