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Hi I am trying to identify what I think is a varistor. The problem I am having is the markings, other than the voltage don't seem to corrolate with anything. So I'm not sure if it is a varistor or if it just has obscure markings. The markings are : 05 K385 1146 I know the k385 is the voltage from what I can find, but have no idea what the current is or what part number it matches up with. It's currently part of the 12v input on an electric fence energiser.

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That looks like the TDK-EPCOS logo (found on a Google image search for "varistor logo"). They happen to make varistors which makes it even more plausible.

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Why is your sample stuck in a tortilla? I can see the herbs.

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  • \$\begingroup\$ It's a varitilla! \$\endgroup\$ – winny Oct 6 '16 at 20:58
  • \$\begingroup\$ interesting background analysis, but the brand logo is irrelevant to finding/choosing/locating a suitable lightning transient replacement (warning opinion) \$\endgroup\$ – Tony Stewart EE75 Oct 6 '16 at 21:52
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    \$\begingroup\$ I didn't think knowing the manufacturer is irrelevant, @Tony. OP couldn't trace the part number and, so, doesn't know the specs which, in turn, makes choosing a replacement a guessing game. Having the manufacturer's name both narrows the search to their datasheets and gives the option of contacting the manufacturer directly. \$\endgroup\$ – Transistor Oct 6 '16 at 21:59
  • \$\begingroup\$ It is irrelevant also because TDK no longer makes this part but do support 05 series (lowest Joule rating ) in lower V,, but now I have a sudden urge to make Burritos \$\endgroup\$ – Tony Stewart EE75 Oct 6 '16 at 22:02
  • \$\begingroup\$ OK. Let's let others decide if it's relevant or not. \$\endgroup\$ – Transistor Oct 6 '16 at 22:04
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It's an EPCOS (now TDK) brand MOV. The 05 is not the Joule rating, it indicates the series name which is S05. Here's the datasheet. Measure its diameter and lead distance, you can find it in the datasheet. I think its part number is this: B72205S0381K101

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  • \$\begingroup\$ Thanks, it's 4mm thick by about 5mm wide , the problem is that size doesn't match anything near in the 385v section. \$\endgroup\$ – Iain Simpson Oct 6 '16 at 19:16
  • \$\begingroup\$ good find Rohat. ! If it were me with an electric fence energizer, I'd still chose the 630 Joules rated part , which I selected .Also the 05 series and 07 series were both dropped by TDK from the 385V rated devices presumeably due to whimpy Joule ratings <25 Joules and the negligible cost differences. \$\endgroup\$ – Tony Stewart EE75 Oct 6 '16 at 21:59
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Metal OXide Variators (MOV) or now generically referred to as SIOV's are commonly rated by their RMS withstanding voltage or 385Vac in this case, then above this by a Joule rating 05 (which seems low).

  • then followed by a date code YYWW for year and week.

These must follow a transient filter and current limiting, otherwise they may fail frequently or sooner than expected with limited number of Joules protection cycles. This one is <5 yrs old in photo, consider the largest Joule rating of radial thruhole 385V MOV for replacement. (low cost)

http://www.digikey.com/product-detail/en/littelfuse-inc/V25S385P/F7181-ND/2297519. .. good choice for lightning protection. 22kA 625 Joules 385Vac working voltage

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