In article <
b78946c6-8a01-46e0...@googlegroups.com>,
peterw...@gmail.com says...
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> Go to any site, any manufacturer - and you will find motor-start caps to be electrolytics. Really. Better yet, just open one up. And, exactly, how do you think they are made?
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> Peter Wieck
> Melrose Park, PA
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>
This will be my last post on this thread. There is no use in me trying
to educate a person that will not be educated . Unless you can point me
to a page that specifies an electrolytic capacitor for a run and/or
start capacitor for an AC motor. And I do not mean the capacitors used
in a varitabble speed drive, just an ordinary AC motor.
If you go to the last sentence or two it will tell you that they are not
suited for use on AC lines.
Here is a quote from your belovied Wiki
https://en.wikipedia.org/wiki/Electrolytic_capacitor
Reverse voltage
An exploded aluminum electrolytic capacitor on a PCB
Standard electrolytic capacitors, and aluminum as well as tantalum and
niobium electrolytic capacitors are polarized and generally require the
anode electrode voltage to be positive relative to the cathode voltage.
Nevertheless, electrolytic capacitors can withstand for short instants a
reverse voltage for a limited number of cycles. In detail, aluminum
electrolytic capacitors with non-solid electrolyte can withstand a
reverse voltage of about 1 V to 1.5 V. This reverse voltage should never
be used to determine the maximum reverse voltage under which a capacitor
can be used permanently.[51][52][53]
Solid tantalum capacitors can also withstand reverse voltages for short
periods. The most common guidelines for tantalum reverse voltage are:
10 % of rated voltage to a maximum of 1 V at 25 °C,
3 % of rated voltage to a maximum of 0.5 V at 85 °C,
1 % of rated voltage to a maximum of 0.1 V at 125 °C.
These guidelines apply for short excursion and should never be used to
determine the maximum reverse voltage under which a capacitor can be
used permanently.[54][55]
But in no case, for aluminum as well as for tantalum and niobium
electrolytic capacitors, may a reverse voltage be used for a permanent
AC application.
To minimize the likelihood of a polarized electrolytic being incorrectly
inserted into a circuit, polarity has to be very clearly indicated on
the case, see the section on "Polarity marking" below.
Special bipolar aluminum electrolytic capacitors designed for bipolar
operation are available, and usually referred to as "non-polarized" or
"bipolar" types. In these, the capacitors have two anode foils with
full-thickness oxide layers connected in reverse polarity. On the
alternate halves of the AC cycles, one of the oxides on the foil acts as
a blocking dielectric, preventing reverse current from damaging the
electrolyte of the other one. But these bipolar electrolytic capacitors
are not adaptable for main AC applications instead of power capacitors
with metallized polymer film or paper dielectric.