Varistor specification in old schematic

Sun Jan 29, 2012 3:33 pm   

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.

Sun Jan 29, 2012 3:33 pm   

Daku wrote:

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

Sun Jan 29, 2012 6:13 pm   

On Sun, 29 Jan 2012 05:33:29 -0800, Daku wrote:


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)

Sat Feb 04, 2012 5:01 am   

On Sun, 29 Jan 2012 09:16:54 -0500, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa__at_charter.net> wrote:


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

?-)