Spark gaps versus Varistors
Spark gaps versus Varistors
(OP)
I am curious if any one call tell me the advantages or disadvantages of using a spark gap over a varistor for over voltage protection.
We are using a spark gap to keep an output voltage from going over 400Vrms.
We are using a spark gap to keep an output voltage from going over 400Vrms.






RE: Spark gaps versus Varistors
Regards
Ralph
RE: Spark gaps versus Varistors
RE: Spark gaps versus Varistors
RE: Spark gaps versus Varistors
RE: Spark gaps versus Varistors
RE: Spark gaps versus Varistors
400V seems quite low for repeatable triggering of spark gaps, and may be affected by routine change in atmospheric conditions.
RE: Spark gaps versus Varistors
RE: Spark gaps versus Varistors
1. In order to flashover, the voltage rise time must be very steep and is in fact a higher rise time that requires derating of insulation.
2. A spark gap that is the minimum amount that can be used will continue to arc after the lightning strike until the power is deenergized. This is one of the reasons why insulators flash over and the power has to be turned off and reclosed to stop a continuing arcing fault.
On their 7,620Y13,200 volt overhead distribution lines Florida Power and Light either uses a 250% insulation level with lightning arrestors every 3 pole OR and overhead neutral. Usually the overhead neutral is used only in rural areas where there is no chance that some of the arrestors can be protecting a transformer anyways like in urban areas. The reason why is that Florida has heavy duty lightning that requires heavy duty wiring.
Mike Cole, mc5w@earthlink.net