×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

AC Electrolytic Capacitor Question

AC Electrolytic Capacitor Question

AC Electrolytic Capacitor Question

(OP)
Hello All,

I have a brief question regarding polar electrolytic capacitors in AC applications.  My understanding is that the use of polar electrolytic capacitors is acceptable in AC circuits if two are placed in series but with opposite orientations.  What is the effective capacitance of this arrangement?  

My understanding is that these capacitors will conduct if a voltage >2V is imposed in the reverse polarity.  Because of this, I think the effective capacitance is equal to that of a single capacitor (i.e., it's not halved) while the ESR is doubled.  I can't measure this with my RCL meter because it does not have a great enough output voltage.

Thanks for any help.
 

RE: AC Electrolytic Capacitor Question

Don't do that!

You can have the back-to-back arrangement, but put a diode parallel to each capacitor so it doesn't get any reverse polarity. Reverse polarity erodes the Al2O3 insulating layer very quickly.
You will get zero-crossing distorsion. But that a price you have to pay if you select this sneak solution. Better buy real AC electrolytics - or us film capacitors.

Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources