Bravheart
"Tomorrow will be a good day"captain Tom1920-2021
- Messages
- 843
- Location
- Scotland
I'm sure this is correct but it's above my intelligence level, all I know is we had a lightning strike on the wires once and the guy at the end of the line had most of his white goods, TV etc. go up in smoke.MOVs age in use which causes the threshold voltage to drop to the point where the normal mains will trigger it. The mains tends to be higher in the middle of the night when there is less demand.
For those who don‘t know Metal Oxide Varistors have a high resistance below the threshold voltage. Their resistance drops rapidly with increasing voltage above the threshold voltage. They are used to suppress transient voltages which whilst high are short duration so limited energy, the MOV can cope with the limited energy and survive. When they get old the threshold drops below the mains voltage and as they are not conti rated ……. BANG.
P.S. It would have been worse if the electric blanket was off at the time!