Varistor specification in old schematic

Jan 29, 2012 3 Replies

Could some electronics guru please clarify this a bit. Looking through an old schematic by a previous colleague I see a varistor specified as MOV 270/20. What does the '270/20' mean ? Thanks for your help.



more than likely means it can operate up to

270 RMS volts continuos and have a clamping ability of 20J/msec.. that would be Joules in energy

That is only a guess from experience. If this circuit must live in a 240V RMS environment, it sounds to be correct.

Jamie

270V. 20mm diameter metal oxide varistor.

Be careful, some manufacturers number(ed) MOVs by RMS operating voltage, some by varistor voltage. PITA, I know.

You need to know the actual operating voltage, then select a suitable 20mm replacement.

Epcos used to number like you wrote. Since the TDK merger, they've changed.

"For a successful technology, reality must take precedence over public relations, for nature cannot be fooled." (Richard Feynman)

No. That device rating is for a 120 V environment.

?-)

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