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bettsd44
Active Contributor

Join Date: Feb 2008
Posts: 16

Capacitance Standards and DF

04/25/2008 3:50 PM

Have set of HP air standards. Have been calibrated by outside vendor and here in house.

Have a capcacitance meter that came back from repair and failing on kHz on DF for about every check listed in manual. Vendor saying since we do not have DF values from calibration, they say it is our standards. Tested 13 other of the same model and can not get any to fail. Followed their procedure on all as well as ours (which was virtually the same).

I feel the unit is not repaired right after so many other pieces passing and the air standards do not calibrate the equipment, only see if can read the standard within spec.

Any suggestions?
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Electroman
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United Kingdom - Member - Olde Member!! Engineering Fields - Instrumentation Engineering - New Member

Join Date: Jul 2006
Location: Dunstable, England
Posts: 2821
Good Answers: 45
#1

Re: Capacitance Standards and DF

04/26/2008 8:30 AM

Ooooowwww right up my street as I'm involved in making capacitance standards at the moment (and for the last several years!)

Are the standards you are using the HP 16380 series? 0.1%?

They are superb and extremely expensive, trust them not some repair house that sounds like they've mucked up the calibration of your instrument...

You are using 5 terminal connection aren't you? 4 would do but 3 and 2 connections would cause problems with measuring accuracy especially at different measuring frequencies...

I have a couple of standards on ebay at the moment calibrated for 0.02% (not that I'm trying to push the price up but why not?!!)

Believe your standards first and the repair company second!!

John

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Electroman
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#2
In reply to #1

Re: Capacitance Standards and DF

04/26/2008 8:32 AM

Oh forgot to mention, using 4 or 5 terminal connections on those HP 16380 series capacitors will give an extremely accurate and low value of dissipation factor...

Uing a resistor in series or parallel will enable you to very accuratly calibrate the instrument for dissipation factor as well as capacitance...

John.

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Shyam
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India - Member - Sensors Technology Popular Science - Cosmology - Dream, Think and Act United Kingdom - Member - New Member United States - Member - New Member Canada - Member - New Member

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Location: AM-51, Deen Dayal Nagar, Gwalior, Madhya Pradesh, MP 474001, India
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Good Answers: 32
#3
In reply to #1

Re: Capacitance Standards and DF

04/26/2008 8:45 AM

I think vacuum capacitors will be ideal as standards. Watch out for vacuum leaks also. Materials as dielectric will have time dependent characteristics.

__________________
 Prof. (Dr.) Shyam, Managing Director for Sensors Technology Private Limited. Gwalior, MP474001, India.
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bettsd44
Active Contributor

Join Date: Feb 2008
Posts: 16
#4
In reply to #1

Re: Capacitance Standards and DF

04/26/2008 4:38 PM

Yes , they are the 16380 series. 1pf,10pf,100pf,1000pf,.01uf,.1uf and 1uf.

Again, the company has done a great job on repair due to no one else can or will fix the old units, but to test 13 other pieces and they pass, left alot of questions that just saying the DF is why on the standards.

Will check yours out. quick way to site?
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Electroman
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#5
In reply to #4

Re: Capacitance Standards and DF

04/27/2008 8:50 AM

This is the ongoing auction on the dot com web site...

http://cgi.ebay.co.uk/Precision-10-nF-Stable-Capacitance-Standard-0-02-NEW_W0QQitemZ270230318663QQcmdZViewItem

and this is one of my web sites which I've quickly put up just for calibration components, its not finished yet so its a bit of a mess.

http://www.measuring-instruments.co.uk/

I hope its okay to put these links on here??

John.

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Electroman
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Location: Dunstable, England
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#6

Re: Capacitance Standards and DF

04/27/2008 9:50 AM

bettsd44, what make of capacitance meter is it? I restore old and not so old LCR bridges and other electronic instruments as a hobby...

Just interested, it could be one I've come across before.

John.

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Anonymous Poster
#7
In reply to #6

Re: Capacitance Standards and DF

04/28/2008 8:25 AM

most are 4278A. some with major issues, some just a board (mainly A6 and 8).

Will look into your auction.
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Anonymous Poster (1); bettsd44 (1); Electroman (4); Shyam (1)

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