Maximum Safety in Surge Protection
Performance of Surge Protection Device (SPD)
Normally, people pay a lot of attention on the performance of a surge protection device (SPD) like its surge capacity. Surge capacity is indeed very important. There are too many surge protection devices (SPDs) on the market can not meet the surge capacity it proclaimed. Here is a picture and video of a SPD that exploded at surge current test (Imax 40kA):
Safety of Surge Protection Device (SPD)
Yet few attention is paid on the safety of a surge protection device. However, bad designed SPD can be extremely dangerous and is one of the major causes for fire hazard. Below is some burnt SPD pictures:
SPD/MOV is the Victim of Temporary Overvoltage (TOV)
SPDs not properly designed or incorrectly used and unprotected MOVs may go into thermal runaway, resulting in short circuit, overheating, smoke and potentially fire hazard due to:
- End of life
- Sustained abnormal overvoltage / Temporary Overvoltage (TOV)
- Surge with unexpected energy
MOV or SPD are protectors of Transient Overvoltage (or surge) but victims of Temporary Overvoltage.
Temporary Overvoltage VS Transient Overvoltage
Temporary Overvoltage (TOV) | Transient Overvoltage | |
| Caused by | LV/HV-system faults | lightning or switching overvoltage |
| Duration | Long millisecond to a few minutes or hours | Short Microseconds (lightning) or millisecond (switching) |
| MOV status | Thermal runaway | Self-recovery |
TOV is more destructive to SPD as its duration is much longer
Temporary Overvoltage is Common
TOV is a very common problem in power quality
Prosurge.in.th (ProSurge Thailand)
By Sun Electric and Supply Co.,Ltd.
31-33 ซ.พิพัฒนา1 ถ.สุขุมวิท ต.ศรีราชา อ.ศรีราชา จ.ชลบุรี 20110
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