On 13 Aug 2006 14:52:34 -0700, "bud--" <budnews@xxxxxxx> wrote:
>John Fields wrote:
>> >>>Nobody has yet answered my question: what are typical one-shot versus
>> >>>lifetime joule ratings for MOVs?
>> >>I don't think there _is_ a one-shot rating after which the device
>> >>has to be replaced.
>> >So any MOV can absorb a megajoule?
>> I don't think so, and I don't think that's what can be inferred from
>> what I said.
>> John Popelish posted something interesting relating to your query.
>> Did you read it?
>One of the parameters of a MOV is the Maximum Continuous Operating
>Voltage which is the voltage at which a MOV starts to conduct,
>specifically the voltage (on average - lot of individual variation) at
>which the current is 1ma. The MOV Joule rating is the single shot
>energy absorption that shifts the MCOV by 10% (lower) which can be
>considered a performance limit. At lower (but still relatively high)
>energy hits, the MOV can progressively degrade.
>With lower (but still relatively high) energy hits the MOV can have a
>much longer life. See w_'s post:
>Fig 7-11 which gives the number of pulses that can be absorbed (1 to 1
>million) at different surge current vs duration combinations - from
>which surge energy can be calculated..
Excellent data sheets, thanks.
Professional Circuit Designer